Criteria for Incoming Inspection for Fruit

MATURITY INDICES & STORAGE CONDITIONS FOR FRESH FRUITS & VEGETABLES

T.L.V.PEIRIS

Contents Page numbers

Introduction 4

VegetablesBell Pepper 5 Breadfruit 7 Brussels Sprouts 8 Broccoli 10 Cabbages (Round and Chinese types) 13 Carrot 15 Cauliflower 18 Celery 20 Cucumber 23 Eggplant 25 Globe Artichoke 28 Garlic 30 Green Asparagus 32 Jackfruit 35 Mushroom 36 Lettuce: Crisphead or Iceberg 38 Okra 41 Onion: Dry 43 Onion: Green Bunching 45 Pepino 47 Pumpkin & Winter Squash 49 Quince 51 Radish 53Spinach 55Sweet Potato 60Tomato 62

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FRUITS

Avocado 66Banana 69Cantaloupe 73Durian 76Grape 80Guava 82Honeydew Melon 85Kiwifruit 88Lemon 90Lime 93Mango 95Mangosteen 100Papaya 102Pineapple 105Plantain Banana 108Pomegranate 111Orange 113Pawpaw 115Strawberry 119Watermelon 121Compatible Fresh Fruits and Vegetables during 7 day storage 124Storing Fresh Fruits and Vegetables for Better Taste 125Proprties and recommended conditions for long term storage of Fresh fruits and vegetables 127

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Introduction

This report was a result of the project which was executed by Quality Assurance Department of CBS (Consolidated Business Systems (Pvt) Ltd) in order to find a solution for never ending customer complains which we receive for our fresh fruits and vegetable products which we export.

This report gives factors such as maturity indices Quality Indices, Optimum Temperature for storage, Optimum Relative Humidity, Rates of Respiration Rates of Ethylene Production, Responses to Ethylene, Responses to Controlled Atmospheres (CA), Physiological Disorders and Insect Control which are useful in maintaining of post harvest quality of fresh fruits and vegetables.

There is no doubt that the post harvest quality maintaining procedures should start at farm it self. This report mainly aims on criteria which are helpful in selection and sorting of fruits, storage and method to extend its shelf life.

Furthermore this report gives some tips on designing of a vegetable packing floor and transportation systems to maintain quality of our food products.

It should be emphasized that methods and procedures are very specific to a company. It should be designed according to the necessities of the company and according to customer requirements. The base for such planning is given by this report.

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Vegetables

Bell Pepper

Maturity Indices

Green Peppers: fruit size, firmness, color Colored Peppers: minimum 50% coloration

Quality Indices Uniform shape, size and color typical of variety Firmness Freedom from defects such as cracks, decay, sunburn

Optimum Temperature

Peppers should be cooled as soon as possible to reduce water loss. Peppers stored above 7.5°C (45°F) suffer more water loss and shrivel. Storage at 7.5°C (45°F) is best for maximum shelf-life (3-5 weeks); peppers can be stored at 5°C (41°F) for 2 weeks, and although this reduces water loss, chilling injury will begin to appear after that period. Symptoms of chilling injury include pitting, decay, discoloration of the seed cavity, softening without water loss. Ripe or colored peppers are less chilling sensitive than green peppers.

Optimum Relative Humidity

> 95%; firmness of peppers is directly related to water loss

Rates of Respiration

Temperture 5°C(41°F) 10°C(50°F) 20°C(68°F)ml CO2/kg·hr 3-4 5-8 18-20

To calculate heat production multiply ml CO2/kg·hr by 440 to get BTU/ton/ day or by 122 to get kcal/metric ton/day.

Rates of Ethylene Production

Bell peppers are nonclimacteric in behaviour and produce very low levels of ethylene: 0.1-0.2 µl/kg·hr at 10°-20°C (50°-68°F).

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Responses to Ethylene

Bell Peppers respond very little to ethylene; to accelerate ripening or color change, holding partially colored peppers at warm temperatures of 20-25°C (68-77°F) with high humidity (>95%) is most effective.

Responses to Controlled Atmospheres (CA)

Peppers generally do not respond well to CA. Low O2 atmospheres (2-5% O2) alone have little effect on quality and high CO2 atmospheres (>5%) can damage peppers (pitting, discoloration, softening) especially if they are stored below 10°C (50°F). Atmospheres of 3% O2+ 5% CO2were more beneficial for red than green peppers stored at 5°C (41°F) to 10°C (50°F) for 3-4 weeks.

Physiological Disorders

Blossom end rot. This disorder occurs as a slight discoloration or a severe dark sunken lesion at the blossom end; it is caused by temporary insufficiencies of water and calcium and may occur under high temperature conditions when the peppers are rapidly growing.

Pepper speck. This disorder appears as spot-like lesions that penetrate the fruit wall; cause is unknown; some varieties are more susceptible than others.

Chilling injury. Symptoms of chilling injury include surface pitting, water-soaked areas, decay (especially Alternaria), and discoloration of the seed cavity.

Pathological Disorders

On California-grown bell peppers, the most common decay organisms are Botrytis, Alternaria, and soft rots of fungal and bacterial origin.

Botrytis or Grey mold decay. This is a common decay-causing organism on peppers; field sanitation and prevention of wounds on the fruit help reduce its incidence. Botrytis will grow well at the recommended storage temperatures. High CO2levels (>10%) which can control Botrytis damage peppers. Hot water dips of peppers can effectively control botrytis rot ( 55°C [130°F] water for 4 minutes) without causing fruit injury.

Alternaria rot. the presence of black Alternaria rot, especially on the stem end of the pepper is a symptom of chilling injury; best control measure is to store at 7.2°C (45°F)

Bacterial Soft Rot. Soft rotting areas can be caused by several bacteria which attack damaged tissue; soft rots can also be common on washed or hydrocooled peppers where water sanitation was deficient.

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Other Common Post harvest Defects

Mechanical damage (crushing, stem punctures, cracks, etc.) is very common on peppers; physical injury not only detracts from the visual quality of the peppers but also causes increased weight loss and decay.

Breadfruit

Maturity Indices

Fully mature fruits are dark-green and their segments are more rounded and smoother than less mature fruits. Latex stains may be present on the skin of mature fruits. Yellowing of the skin indicates over-maturity (partial ripeness). In some cases, fruits are picked when fully ripe and sweet for consumption as a dessert.

Mature bread fruit immature bread fruit

Quality Indices

Good quality breadfruits are mature-green, firm, with intact stem, and free from defects (such as blemishes, sunscald, cracking, bruising, and insect damage) and decay. Uniformity of shape, size, and weight is also important as quality factors. Breadfruit pulp (edible portion) contains 25-30% (fresh weight basis) carbohydrates, half of which is starch. The pulp is boiled, baked, fried, or roasted, but never eaten raw. It is also ground into flour that is used in bread-making.

Optimum Temperature

13 ± 1°C (56 ± 2°F); storage potential = 2-4 weeks, depending on cultivar and maturity stage.


85-95%


The range of respiration rates at 20°C (68°F) is 38 (preclimacteric) to 178 (climacteric peak) ml CO2/kg·hr.

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To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.


The range of ethylene production at 20°C (68°F) is 0.1 (preclimacteric) to 1.6 (climacteric peak) µl/kg·hr.


Exposure to 50ppm or higher concentrations of C2H4 for 24 hours at 20°C (68°F) accelerates ripening of breadfruits (as indicated by color changes from green to yellow and softening) and shortens their postharvest-life.


A CA of 5% O2 + 5% CO2 or use of modified atmosphere packaging (5-8% O2 + 8-10% CO2) may be useful in delaying ripening (softening) and extending postharvest-life of mature-green breadfruits kept within the optimum ranges of temperature and relative humidity.


Chilling Injury: Fruits kept at temperatures below 12°C (54°F) before transfer Disorders to higher temperatures exhibits the following symptoms of chilling injury: brown discoloration of the skin, pulp browning and off-flavor development, and increased susceptibility to decay.


Pathological disorders usually follow mechanical damage and/or chilling injury of breadfruits. Decay may be caused by Phytophthora palmivora or Rhizopus artocarpi or Botryobasidium salmonicola.

Brussels Sprouts

Maturity Indices

Brussels sprouts are the compact vegetative buds that develop along the stem of the Brussels sprouts plant. They should be harvested when the buds are firm, but not overmature which is indicated by splitting of the outer leaves.

Quality Indices

Good quality Brussels sprouts should be bright green, without yellowing or discoloration, and have a firm texture. The butt end may be slightly discolored, but should not be dark.

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Brussels sprouts should be sweet and mild in flavor when cooked. Bitterness varies among cultivars and is associated with high concentrations of specific glucosinolates (sinigrin and progoitrin). Bitterness can also be induced by storage conditions (see Responses to Controlled Atmospheres).

Optimum Temperature and Relative Humidity

Brussels sprouts are moderately perishable and can be stored 3-5 weeksat temperatures near the optimum of 0°C (32°F) with >95% RH. Shelf life at 5°C (41°F) is 10-18 days and at 10°C (50°F) is less than 7 days. Brussels sprouts are often hydrocooled, but can be air cooled as well. Although they have considerable wax on their leaves, they become flaccid due to water loss if high relative humidity is not maintained.

Freezing Injury

Brussels sprouts freeze at about -0.6°C (30.9°F). Slight freeze damage on the outer leaves of buds may result in small dark and translucent areas. Severe freeze damage results in the entire bud becoming dark and translucent, and very soft after thawing.


Brussels sprouts have relatively high respiration rates. The highest rate at each temperature corresponds to measurements within 1-2 days of harvest.

Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C (68°F)

ml CO2 / kg·hr 5 - 15 11 - 24 20 - 40 30 - 50 45 - 75

§ To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton-day.


Ethylene production rates are slightly higher than those of other green and leafy vegetables, but can still be classified as low: <0.25 µl/kgo·hr at 2.5-5°C (36-41°F). Rates are higher in Brussels sprouts that show any yellowing, and in sprouts removed from beneficial controlled atmospheres.

Responses to Ethylene Brussels sprouts are sensitive to exposure to ethylene. Leaf yellowing and leaf abscission are the most common symptoms of ethylene injury.

Responses to Controlled Atmosphere (CA)

Brussels sprouts can be benefited by 1-4% O2 with 5-10% CO2 atmospheres at 2.5-5°C (32-41°F). The main benefits are reduced yellowing and decay, reduced butt discoloration and inhibition of ethylene production. No benefits of CA are observed if the

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Brussels sprouts are kept at their optimum storage temperature 0°C (32°F). Low oxygen storage (<1%) can cause extreme bitterness and may also cause internal discoloration. Atmospheres of 10-12% CO2 can result in off-flavors and off-odors.


Puffiness or lack of firmness is undesirable in the buds and may vary among cultivars and growing conditions.

Internal browning can occur under very wet production conditions and is associated with condensation on the developing leaves.

Physical Injury

Rough handling at harvest can bruise the buds and increase decay.


Brussels sprouts are not very prone to postharvest decay, but may be affected by the same organisms that infect other Brassica vegetables. Bacterial decay due to various soft-rot causing organisms (Erwinia, Pseudomonas) may infect sprouts, but bacterial decay is usually associated with physical injury. Less common are fungal pathogens, which can occur under rainy and cool growing conditions.

Broccoli

Maturity Indices

Head diameter and compactness; all florets (beads) should be closed.

Quality Indices

Good quality broccoli should have dark or bright green closed florets, and the head should be compact (firm to hand pressure), with a cleanly cut stalk of the required length. There should be no yellow florets and there should be no discoloration on the stem bracts.


Low temperature is extremely important to achieve adequate shelf-life in broccoli. A temperature of 0°C (32°F) with >95% RH is required to optimize broccoli storage life (21-28 days). Heads stored at 5°C (41°F) can have a storage life of 14 days; storage life at 10°C (50°F) is about 5 days. Broccoli is usually rapidly cooled by liquid-icing the field-packed waxed cartons. Hydrocooling and forced-air cooling also can be used, but temperature management during distribution is more critical than with iced broccoli.

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Freezing Injury

Broccoli will freeze if stored at -0.6°C (30.6°F) to -1.0°C (30°F). This may also occur if salt is used in the liquid-ice cooling slurry. Frozen and thawed areas on the florets appear very dark and translucent, may discolor after thawing and are very susceptible to bacterial decay.


Broccoli heads have relatively high respiration rates:

Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C (68°F)ml CO2/kg·hr 10-11 16-18 38-43 80-90 140-160

The respiration rates of florets are slightly more than twice the rates of the intact heads.

To calculate heat of production multiply ml CO2/kg·hr by 440 to get Btu/ton-day or by 122 to get kcal/metric ton-day.


Very low, <0.1 µL/kg·h at 20°C (68°F).


Broccoli is extremely sensitive to exposure to ethylene. Floret yellowing is the most common symptom. Exposure to 2 ppm ethylene at 10°C (50°F) reduces shelf-life by 50%.


Broccoli can be benefitted by 1-2% O2 with 5-10% CO2 atmospheres at a temperature range of 0-5°C (32-41°F). Although under controlled conditions such low O2 levels extend shelf-life, temperature fluctuations during commercial handling make this risky as broccoli can easily produce offensive sulfur-containing volatiles. As a result, a high rate of air exchange is recommended in standard marine container shipments of broccoli. Most modified atmosphere packaging for broccoli is designed to maintain O2 at 3-10% and CO2 at about 7-10% to avoid the development of these undesirable off-odor volatiles.


Hollow stem is an open area in the stem at the cut surface which may become discolored and decay; growing conditions and variety selection affect development of this disorder.

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Floret (bead) yellowing. The florets are the most perishable part of the broccoli head; yellowing may be due to overmaturity at harvest, high storage temperatures, and/or exposure to ethylene. Any development of yellow beads ends commercial marketability. Bead yellowing due to senescence should not be confused with the yellow-light green color of areas of florets not exposed to light during growth, sometimes called "marginal yellowing".

Brown floret (bead). Is a disorder in which areas of florets do not develop correctly, die and lead to brown discolored areas. This is thought to be caused by plant nutritional imbalances.

Physical Injury

Rough handling at harvest can damage the florets and increase decay. The force used to apply the water-ice slurry for cooling can also damage the florets on the heads and increase susceptibility to bacterial decay.


Bacterial decay . Various soft-rot causing organisms (Erwinia, Pseudomonas) may affect broccoli shelf-life. Rots due to these organisms are usually associated with physical injury.

Fungal pathogens. Although not as common as bacterial rots, gray mold rot (Botrytis cinerea) and black mold (Alternaria spp.) can infect broccoli heads; this may occur under rainy, very cool growing conditions.

Special Considerations

Storage life varies considerably among broccoli cultivars. Shelf-life (appearance of any yellow beads = end of shelf-life) may vary from 12 to >25 days depending on cultivar: Shelf-life of different broccoli cultivars stored at 5°C (41°F), and 95% RH:

Short (<20 Days): Baccus, Brigadier, Cruiser, Mariner, Symphony, Zeus

Moderate (20 to 25 days): Cascade, Embassy, Emperor, Esquire, Galaxy, Gem, Green Lady, Green Valiant, Hi Caliber, Midori #8, Pinnacle, Sakata #12, Schooner, Southern Comet, Vantage

Long (>25 days): Citation, Galaxy, Glacier, Greenbelt, Legacy, Marathon, Mercedes, Packman, Pirate, Premium Crop, Shogun, Skiff

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Cabbages (Round and Chinese types)

General Information

Round hard cabbages and Chinese (also called Napa) cabbages are from the same genus (Brassica) but different species (B. oleracea var capitata = cabbage, B. campestris var. pekinensis = Chinese cabbage). Chinese cabbages may be cylindrical or rounded and may be less compact than round cabbages. Information mentioned here applies to both types unless stated otherwise.

Maturity Indices

Maturity is based on head compactness. A compact head can be only slightly compressed with moderate hand pressure. A very loose head is immature, and a very firm or hard head is mature.

Quality Indices

After trimming outer wrapper leaves, cabbage heads should be a color typical of the cultivar (green, red, or pale yellow-green), firm, heavy for the size and free of insect, decay, seed stalk development and other defects. Leaves should be crisp and turgid. For round cabbages, grades are U.S. no. 1 and U.S. commercial.


Most cabbage is room cooled. Storage at 0°C (32°F) with >95% RH is required to optimize cabbage storage life. Early crop round cabbage can be stored 3-6 weeks, while late crop cultivars can be stored for up to 6 months. For the latter, storage at -0.5°C (31°F) is sometimes recommended. Chinese cabbage can be stored from 2 to 6 months, depending on cultivar, at 0° to 2.5°C (32° to 36°F). Deterioration of cabbage during storage is associated with stem or seed stalk growth (bolting), root growth, internal breakdown, leaf abscission, discoloration, decay and black speck. Long-term storage usually results in extensive trimming of heads to remove deteriorated leaves.

Freezing Injury Freeze damage appears as darkened translucent or water-soaked areas that will deteriorate rapidly after thawing. Freeze damage can occur if round cabbages are stored below -0.9°C (30.4°F) and if Chinese cabbage is stored below -0.6°C (31°F). Rates of Respiration

Round and Chinese cabbages have similar moderately low respiration rates:

Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C (68°F)ml CO2/kg·hr 2 - 3 4 - 6 8 - 10 10 - 16 14 - 25

Respiration rates of shredded cabbage are 13-20 mL CO2/kg·hr at 5°C (41°F).

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To calculate heat production multiply mL CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.


Ethylene production rates are generally very low: <0.1 µL/kg·hr at 20°C (68°F), although higher rates have been reported for Chinese cabbage.


Cabbages are sensitive to ethylene, which causes leaf abscission and leaf yellowing. Adequate ventilation during storage is important to maintain very low ethylene levels. Ethylene does not increase the disorder "black speck" or "pepper spot".


Some benefit to shelf-life can be obtained with low O2 (2.5-5%) and high CO2 (2.5-6%) atmospheres at temperatures of 0-5°C (32-41°F). CA storage will maintain color and flavor of cabbage, retard root and stem growth, and reduce leaf abscission. O2 atmospheres below 2.5% for round cabbage and 1% for Chinese cabbage will cause fermentation, and CO2 atmospheres >10% will cause internal discoloration.


Black speck: Black leaf speck (also called pepper spot, petiole spot, gomasho) is a disorder that consists of very small to moderate size discolored lesions on the midrib and veins of the leaves. The symptoms can occur after low temperatures in the field and by harvesting overmature heads, but are usually associated with transit and storage conditions. Low storage temperatures followed by warmer temperatures enhance development. Ethylene does not promote development of black speck in Chinese cabbage. Both round and Chinese cabbage cultivars vary widely in their susceptibility to this disorder. Storage with high CO2 atmospheres (10%) can reduce pepper spot development on round cabbage.

Chilling injury: in Chinese cabbage is purported to occur during storage at 0°C (32°F) after 3 months or longer. The main symptom is midrib discoloration, especially on outer leaves. Cultivars differ greatly in their susceptibility to develop midrib discoloration.

Physical Injury

Breakage of the midribs often occurs during field packing and causes increased browning and increased susceptibility to decay. Outer midribs of overmature heads will crack easily.

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The most common decays found in stored cabbage are watery soft rot (Sclerotinia), gray mold rot (Botrytis cinerea), alternaria leaf spot (Alternaria spp.), and bacterial soft rot (caused by various bacterial species including Erwinia, Pseudomonas, Xanthomonas). Bacterial soft-rots result in a slimy breakdown of the infected tissue, and may follow fungal infections. Trimming outer leaves, rapid cooling and low temperature storage reduce development of these rots, although Botrytis and Alternaria will grow at low storage temperatures.


Fresh-cut or shredded cabbage pieces brown during storage and atmospheres of 3-5% O2 and 5-15% CO2 retard discoloration. Too low oxygen levels lead to fermentation and package blow-up, especially if product is not held below 5°C (41°F).

Carrot

Maturity Indices In practice, harvest decisions for carrots are based on several criteria depending

on the market outlet or sales endpoint. Typically carrots are harvested at an immature state when the roots have achieved

sufficient size to fill in the tip and develop a uniform taper. Length may be used as a maturity index for harvest timing of ‘cut and peel'

carrots to achieve a desired processing efficiency.

Quality Indices

There are many visual and organoleptic properties that differentiate the diverse varieties of carrots for fresh market and minimal processing. In general, Carrots should be:

Firm (not flacid or limp) Straight with a uniform taper from ‘shoulder' to ‘tip' Bright orange There should be little residual "hairiness" from lateral roots No "green shoulders" or "green core" from exposure to sunlight during the growth

phase. Low bitterness from terpenoid compounds High moisture content and high reducing sugars are most desireable for fresh

consumption.

U.S. Grades: Bunched Carrots - No. 1 and Commercial Grade Topped Carrots - Extra No.1, U.S. No. 1, No. 1 Jumbo, No. 2

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Quality Defects include lack of firmness, non-uniform shape, roughness, poor color, splitting or cracking, green core, sunburn, and poor quality of tops or trimming.

Optimum Temperature

0°C(32°F)

Storage life at 0°C is typically: Bunched: 10-14 days Immature roots: 4-6 weeks Fresh-cut: 3-4 weeks Mature roots: 7-9 months (Lightly processed)

Common storage conditions rarely achieve the optimum temperature for long- term storage to prevent decay, sprouting, and wilting. At storage temperatures of 3-5 °C, mature carrots can be stored with minimal decay for 3-5 months.

Common ‘Cello-pack' carrots are typically immature and may be stored successfully for 2-3 weeks at 3-5°C. Bunched carrots are highly perishable due to the presence of the shoots (tops). Good quality is generally maintained only for 8-12 days, even with contact ice.

Lighlty processed (fresh-cut, cut and peel) carrots typically maintain quality of 2-3 weeks at 3-5°C.


98-100 % ; High relative humidity is essential to prevent dessication and loss of crispness. Free moisture from the washing process or unevaporated condensation, common with plastic bin-liners ( and due to fluctuating temperatures ) will promote decay.


Temperature °C (°F)

ml CO2 / kg·hr Topped Bunched

0 32 5-10 9-18

5 41 7-13 13-25

10 50 10-21 16-31

15 59 13-27 28-53

20 68 23-48 44-60

25 77 NA NA

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To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day. NA= not applicable


>0.1µl / kg·hr at 20°C (68°F)


Exposure to ethylene will induce the development of bitter flavor due to isocoumarin formation. Exposure to as little as 0.5ppm exogenous ethylene will result in perceptible bitter flavor, within 2 weeks, at normal storage conditions. Thus, carrots should not be mixed with ethylene-producing commodities.

Responses to Controlled Atmospheres(CA)

Controlled atmosphere is of limited use for carrots and does not extend postharvest life of carrots beyond that in air. CO2 concentrations above 5% have been shown to increase spoilage. Low oxygen concentrations, below 3 %, are not well tolerated and generally results in increased bacterial rot.

Physiological & Physical Disorders

Intact Roots Bruising, shatter-cracks and tip-breakage are signs of rough handling. Nantes-type carrots are particularly susceptible. Sprouting will continue as carrot roots develop new shoots after harvest. This is one reason low temperature postharvest management is critical. Common associated disorders include wilting, shriveling, or rubberiness due to dessication. White Root is a physiologic disorder due to suboptimal production conditions which results in patchy or streaks of low color on the carrot roots.

Intact or Fresh-cut Bitterness may be caused by preharvest stress (improper irrigation scheduling) or exposure to ethylene from ripening rooms or mixing with commodities such as apples. Freezing injury will likely result at temperatures of -1.2°C ( 29.5°F) or lower. Frozen carrots generally exhibit an outer ring of water-soaked tissue, viewed in cross section, which blackens in 2-3 days.

Fresh-cut White Blush, due to dehydration of cut or abrasion-peeled surfaces, has been a problem on fresh-cut carrots. Sharp cutting blades and residual free-moisture on the surface of the processed carrots will significantly delay the development of the disorder.

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The most prominent postharvest disease concerns are Gray Mold (Botrytis rot ) Watery Rot ( Sclerotinia rot ), Rhizopus rot, Bacterial Soft Rot, induced by Erwinia carotovora subsp. carotovora and Sour Rot ( Geotrichum rot ). Proper handling and low temperature storage and transportation conditions are the best methods to minimize losses.


Rapid hydrocooling soon after harvest is strongly recommended.

Cauliflower

Maturity Indices

Cauliflowers are selected for size and compactness of the head or curd. Mature curds are at least 15 cm (6 inches) in diameter. Loose or protruding floral parts, creating a ‘ricy’ appearance, are a sign of overmaturity. Cauliflower is packaged after being closely trimmed into single layer cartons of 12 to 24 heads, with 12’s most common.

Cauliflower is primarily marketed with closely trimmed leaves and overwrapped with perforated film. Overwraps should provide four to six 1/4-inch holes per head to allow adequate ventilation.

Quality Indices

A firm and compact head of white to cream white curds surrounded by a crown of well-trimmed, turgid green leaves. Additional quality indices are size, freedom from severe yellowing due to sunlight exposure, freedom from handling defects and decay, and an absence of ‘riciness’. U.S. grade No. 1

Optimum Temperature

0°C (32°F); 95-98% R.H.

Storage of cauliflower is generally not recommended for more than 3 weeks for good visual and sensory quality. Wilting, browning, yellowing of leaves, and decay are likely to increase following storage beyond 3-4 weeks or at higher than recommended storage temperatures.

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Temperature °C Temperature °F ml CO2/kg·hr 0 32 8-9 5 41 10-11 10 50 16-1815 59 21-2520 68 37-4225 77 43-48

§ To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day.


< 0.1 µl /kg· hr at 20°C (68°F)


Cauliflower is highly sensitive to exogenous ethylene. Discoloration of the curd and accelerated yellowing and detachment of wrapper leaf stalks will result from low levels of ethylene during distribution and short-term storage. Do not mix loads such as apples, melons and tomatoes with cauliflower.


Controlled or modified atmospheres offer moderate to little benefit to cauliflower. Injury from low O2 (< 2%) or elevated CO2 (> 5%) may not be visual and will only be evident after cooking. When the curds become grayish, extremely soft, and emit strong off-odor. Higher levels (>10%) of CO2 will induce this injury within 48 hours. Combined low O2 and slightly elevated CO2 levels (3-5%) delay leaf yellowing and the onset of curd browning by a few days.


Freezing Injury- Freezing injury will be initiated at - 0.8°C (30.6°F). Symptoms of freezing injury include a watersoaked and greyish curd and watersoaked or wilted crown leaves. The curd will become brown and gelatinous in appearance following invasion by soft-rot bacteria.

Physical Injury

Harvesting should be done with great care to prevent damage to the highly sensitive turgid curds. Cauliflower should never be handled by the curd portion of the head. Cauliflower should never be allowed to roll or scuff across a harvest -conveyor belt, table, or other work surface.

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Bruising is very common and leads to rapid browning and decay when attention to careful harvest and handling practices are not followed.


Diseases are an important source of postharvest loss, particularly in combination with rough handling and poor temperature control. A large list of bacterial and fungal pathogens cause postharvest losses in transit, storage, and to the consumer. Bacterial Soft-Rot (primarily Erwinia and Pseudomonas), Black Spot (Alternaria alternata.), Grey Mold (Botrytis cinerea), and Cladosporium Rot are common disorders.


For fresh-cut applications, the sensitivity of cauliflower to improper modified atmosphere (See Responses to CA) demands very careful selection of packaging films and proper temperature management.

Celery

Maturity Indices

Celery is harvested when the overall field reaches the desired marketable size and before the outer petioles develop "pithiness" (See Pith Breakdown below). Celery has very uniform crop growth and fields are harvested only once and stalks are packed by size after trimming outer petioles and leaves.

Quality Indices

High quality celery consists of stalks which are well formed, have thick petioles, are compact (not significantly bowed or bulging), have minimal petiole twisting, and have a light green and fresh appearance. Additional quality indices are stalk and midrib length, freedom from defects such as blackheart, pithy petioles, seedstalks, cracks or splits, and freedom from insect damage and decay.

U.S. Grades : Extra No. 1; No. 1; No. 2 ( Grade Standards established 1957) Celery may be sold as "Unclassified" to designate a lot which has not been graded within U.S. standards.

Optimum Temperature

0°C (32°F)

At optimum conditions, celery should have good quality after storage up to 5 to 7 weeks. Commonly, celery is rapidly pre-cooled and then stored at 0 to 2°C (32 to 36°F) if storage is intended to be less than one month storing celery at 5°C (41°F) is not

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recommended for more than 2 weeks. To maintain good visual and sensory quality. Some continued growth of inner stalks will occur postharvest at temperatures >0°C (32°F) .


98-100% R.H.


Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C(68°F) ml CO2/kg·hr* 3 5 12 17 32

*To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.


< 0.1 µl / kg· hr at 20°C (68°F)


Celery is not very sensitive to exogenous ethylene at low levels and low temperatures. Loss of green color can result from exposure to 10ppm or higher ethylene concentrations at above 5°C (41°F).


Controlled or modified atmospheres offer moderate benefit to celery. Delayed senescence and decay development have been observed at 2-4% O2 and 3-5% CO2.

Injury from low O2 (< 2%) or elevated CO2 (> 10%) will induce off-odors, off-flavors, and internal leaf browning. CA for mixed storage or long distance transport of celery and lettuce has some commercial application. Elevated CO2 levels delay leaf yellowing and decay but could not be used in mixed loads with lettuce (lettuce does not tolerate CO2 enriched atmosphere).

Physiological and Physical Disorders

Blackheart. Internal leaves develop a brown discoloration which eventually becomes deep black. The cause is similar to tip-burn of lettuce or blossom-end rot of tomato. Although many predisposing factors may be involved, water-stress results in a calcium deficiency disorder causing cell death.

Brown Checking. Splits, primarily along the inner surface of the petioles result from boron deficiency.

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Freezing Injury. Freezing injury will be initiated at - 0.5°C (31.1°F). Symptoms of freezing injury include a watersoaked appearance on thawing and wilted leaves. Mild freezing causes pitting or short streaks in the petiole which develop a brown discoloration with additional storage.

Pith Breakdown. The breakdown of the internal tissue of the petiole, the pith, is often refereed to as "pithiness" or pithy stems. The aerenchyma tissue of the petiole becomes white, spongy or vacuolated, and appears dry. Pith breakdown is induced by several factors that result in the induction of senescence, including cold stress, water stress, pre-bolting changes (seed stalk induction), and root infections. Pith breakdown will develop after harvest, but slowly under proper storage conditions.

Crushing or cracking. Common and leads to rapid browning and decay. Harvesting, packing and handling should be done with great care to prevent damage to the highly sensitive turgid petioles.


Diseases are an important source of postharvest loss, particularly in combination with rough handling and poor temperature control. The major bacterial and fungal pathogens that cause postharvest losses in transit, storage, and to the consumer are Bacterial Soft-Rot (primarily Erwinia and Pseudomonas), Gray Mold (Botrytis cinerea), and Watery Rot (Sclerotinia spp.). Botrytis and Sclerotinia will develop over a period of a few weeks, even at 2°C (35.6°F).


Cut petioles of celery, as for fresh-cut, are very prone to bacterial decay. Less decay and greatly delayed decay symptoms will result from the use of sharp blades, minimizing abrasions or other damage to cut-ends during packaging, and good sanitation.

Cucumber

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Maturity Indices

Cucumbers are harvested at a range of developmental stages. Depending on cultivar and temperature, the time from flowering to harvest may be 55 to 60 days. Generally fruit are harvested at a slightly immature stage, near full size but before seeds fully enlarge and harden. Firmness and external glossiness are also indicators of a pre-maturity condition. At proper harvest maturity, a jellylike material has begun to form in the seed cavity.

USDA Colour for cucumber

Quality Indices

Table or slicing cucumber quality is primarily based on uniform shape, firmness and a dark green skin color. Additional quality indices are size, freedom from growth or handling defects, freedom from decay, and an absence of yellowing.

U.S. grades are Fancy, Extra 1, No. 1, No. 1 Small, No. 1 Large and No. 2.

Industry grades and specifications follow the packing conventions SuperSelect, Select, Small Super, Small, Large, and Plain. These terms have no enforceable contractual value.


10 - 12.5°C (50 - 55°F); 95% R.H.

Storage of cucumber is generally less than 14 days as visual and sensory quality deteriorate rapidly. Shriveling, yellowing, and decay are likely to increase following storage beyond two weeks, especially after removal to typical retail conditions. Short term storage or transit temperatures below this range (such as 7.2°C / 45°F) are commonly used but will result in chilling injury after 2-3 days.

Chilling Injury

Cucumbers are chilling sensitive at temperatures below 10°C (50°F) if held for more than a day to 3 days depending on temperature and cultivar. Consequences of chilling injury are water-soaked areas, pitting and accelerated decay. Chilling injury is cumulative and may be initiated in the field prior to harvest. Cucumber varieties vary considerably in their susceptibility to chilling injury.

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Temperature 10°C(50°F) 15°C(59°F) 20°C(68°F) 25°C(77°F)

ml CO2/kg·hr 12-15 12-17 7-24 10-26

Respiration varies widely above 10°C due to different stages of maturity. Less mature cucumbers have higher respiration rates. To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day.


0.1 - 1.0µl / kg·hr at 20°C(68°F)


Cucumbers are highly sensitive to exogenous ethylene. Accelerated yellowing and decay will result from low levels (1-5ppm) of ethylene during distribution and short-term storage. Do not mix commodities such as bananas, melons and tomatoes with cucumber.


Controlled or modified atmosphere storage or shipping offer moderate to little benefit to cucumber quality maintainence. Low O2 levels (3-5%) delay yellowing and the onset of decay by a few days. Cucumber tolerates elevated CO2 up (CA) to 10% but storage life is not extended beyond the benefit of reduced levels of O2 .


Freezing Injury. Freezing injury will be initiated at - 0.5°C (31°F). Symptoms of freezing injury include a watersoaked pulp becoming brown and gelatinous in appearance over time.

Physical Injury

Harvesting should be done by cutting free of the vine rather than by tearing. "Pulled end" is a quality defect used in establishing grade quality.

Bruising and compression injury are very common when attention to careful harvest and handling practices are not followed.

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Diseases are an important source of postharvest loss, particularly in combination with chilling stress. A large list of bacterial and fungal pathogens cause postharvest losses in transit, storage, and to the consumer. Alternaria spp., Didymella Black Rot, Pythium Cottony Leak, and Rhizopus Soft Rot are common disorders.


Cucumbers are often treated with approved waxes or oils to reduce water loss, reduce abrasion injury and enhance appearance.

Yellowing during the postharvest period is a very common defect. Harvesting fruit at an advanced stage of development, exposure to ethylene, or storage at too high temperature all cause yellowing.

Eggplant

Maturity Indices

Eggplant fruit are harvested at a range of developmental stages. Depending on cultivar and temperature, the time from flowering to harvest may be 10 to 40 days. Generally fruit are harvested immature before seeds begin to significantly enlarge and harden. Firmness and external glossiness are also indicators of a pre-maturity condition. Eggplant fruit become pithy and bitter as they reach an over mature condition.

Quality Indices

The diversity of eggplant types being marketed has increased greatly in recent years. Standard (American) eggplant quality is primarily based on uniform egg to globular shape, firmness and a dark purple skin color. Additional quality indices are size, freedom from growth or handling defects, freedom from decay, and a fresh green calyx. Other eggplant types include: Japanese - elongated, slender, light to dark purple, very perishable White - small egg shaped to globular, thin skinned Mini-Japanese - small elongate, striated purple and violet Chinese - elongated, slender, light purple

U.S. grades are Fancy, No. 1, and No. 2, and No. 3. Distinction among grades is based solely on size, external appearances, and firmness.

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10 - 12°C (50 - 54°F); 90-95% R.H.

Storage of eggplant is generally less than 14 days as visual and sensory qualities deteriorate rapidly. Decay is likely to increase following storage beyond two weeks, especially after removal to typical retail conditions. Short term storage or transit temperatures below this range are used often to reduce weight loss, but will result in chilling injury after several days.

Chilling Injury

Eggplant fruit are chilling sensitive at temperatures below 10°C (50°F). At 5°C (41°F) chilling injury will occur in 6-8 days. Consequences of chilling injury are pitting, surface bronzing, and browning of seeds and pulp tissue. Accelerated decay by Alternaria spp. is common in chilling stressed fruit. Chilling injury is cumulative and may be initiated in the field prior to harvest.

Days to Visible Chilling Symptoms on each type:

Temperature O°C (32°F) 2.5°C (36°F) 5°C (41°F) 7.5°C (45°F)

American 1-2 4-5 6-7 12

Japanese - 5-6 8-9 12-14

Chinese 2-3 5-6 10-12 15-16


Temperature 12.5°C (55°F)ml CO2/ kg·hr American 30-39ml CO2/ kg·hr White egg 52-61ml CO2/ kg·hr Japanese 62-69

To calculate heat production, multiply ml CO2/ kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day.


0.1 - 0.7µl / kg·hr at 12.5°C (55°F)


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Eggplant fruit have a moderate to high sensitivity to exogenous ethylene. Calyx abscission and increased deterioration, particularly browning, may be a problem if eggplants are exposed to >1ppm ethylene during distribution and short-term storage.


Controlled or modified atmosphere storage or shipping offer little benefit to eggplant quality maintenance. Low O2 levels (3-5%) delay deterioration and the onset of decay by a few days. Eggplant tolerates up to 10% CO2 but storage life is not extended beyond the benefit of reduced levels of O2.


Freezing Injury - Freezing injury will be initiated at - 0.8°C (30.6°F), depending on the soluble solids content. Symptoms of freezing injury include a watersoaked pulp becoming brown and desiccated in appearance over time.

Physical Injury Harvesting should be done by cutting the calyx-stem free from the plant rather than by tearing. Cotton gloves are often used.

Bruising and compression injury are very common when attention to careful harvest and handling practices are not followed. Eggplant cannot withstand stacking in bulk containers.


Diseases are an important source of postharvest loss, particularly in combination with chilling stress. Common fungal pathogens are Alternaria (Black Mold Rot), Botrytis (Gray Mold Rot), Rhizopus (Hairy Rot), and Phomopsis Rot.


Rapid cooling, primarily to reduce water loss, soon after harvest is essential for optimal postharvest keeping quality. The precooling endpoint is typically 10°C (50°F). Forced-air cooling is the most effective practice. Room cooling after washing or hydrocooling is the most common practice. Moistened paper or waxed cartons are often used to reduce water loss. Japanese eggplants lose water 3 times more rapidly than American-type eggplants. Visible signs of water loss are reduction of surface sheen, skin wrinkling, spongy flesh, and browning of the caylx.

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Chilling injury and water loss can be reduced by storing of eggplant in polyethylene bags or polymeric film overwraps. Increased decay from Botrytis is a potential risk of this practice.

Globe Artichoke

Maturity Indices

The edible bud, composed of a cone of bracts, is harvested at an immature stage and selected for size and compactness. Overdeveloped buds have an open or spreading structure; the bracts have a brownish cast and are tough and stringy; the centers have a fuzzy, pink to purple appearance.

Quality Indices

Quality indices are compact and well-formed buds, typical green color, a smooth and uniform stem-cut, freedom from insect damage or handling damage and defects. Artichoke buds should feel heavy for their size. Stems are generally cut 2.5 to 3.8 cm (1 to 1.5 in) below the base.


0°C (32°F) with >95% RH

Hydrocooling, forced-air cooling, and package-icing are common methods of postharvest cooling of artichokes.

Storage potential of artichoke is generally less than 21 days as visual and sensory quality deteriorate rapidly.


Temperature ml CO2 / kg·hr0°C (32°F) 8 – 225°C (41°F) 13 – 3010°C (50°F) 22 – 4915°C (59°F) 38 – 7220°C (68°F) 67 – 126

§ To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton · day.

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Very low ; < 0.1 µl / kg·hr at 20°C (68°F)


Artichokes have a low sensitivity to exogenous ethylene and therefore it is not considered a factor in postharvest handling and distribution.

Responses to CA

Controlled or modified atmospheres offer moderate to little benefit to sustaining artichoke quality. Conditions of 2-3% O2and 3-5% CO2 delay discoloration of bracts and the onset of decay by a few days at temperatures around 5°C (41°F). Atmospheres below 2% O2may result in internal blackening of artichokes.


Freezing Injury. Freezing injury will be initiated at - 1.2°C (29.9°F). Symptoms of light freezing injury are blistering of the cuticle and a bronzing of the outer bracts. This may occur in the field with winter harvested buds and is used in marketing as an index of high quality. More severe freeze injury results in watersoaked bracts and the heart becoming brown to black and gelatinous in appearance over time.

Physical Injury

Bruising and compression injury. Very common when attention to careful harvest and handling practices are not followed.


Grey Mold (Botrytis cinerea) and Bacterial Soft Rot (Erwinia carotovora) may be a problem in storage and distribution if optimum temperature conditions are not met. Opportunistic fungi (such as Fusarium spp.) may develop on cut stems or bracts with prolonged low temperature storage.

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Garlic

Maturity Indices

Garlic can be harvested at different stages of development for specialty markets, but most garlic is harvested when the bulbs are well mature. Harvest occurs after the tops have fallen and are very dry.

Quality Indices

High quality garlic bulbs are clean, white (or other colors typical of the variety), and well cured (dried neck and outer skins). The cloves should be firm to the touch. Cloves from mature bulbs should have a high dry weight and soluble solids content (>35% in both cases).

Grades include U.S. No. 1 and unclassified, and are based primarily on external appearance and freedom from defects. Minimum diameter for fresh market is about 4 cm.(1.5 inches).

Optimum Temperature

-1°C to 0°C (30°-32°F) The variety of garlic affects potential storage life, and the recommended conditions for commercial storage depend on the expected storage period. Garlic can be kept in good condition for 1-2 months at ambient temperatures (20°-30°C [68-86°F]) under low relative humidity (<75%). However under these conditions, bulbs will eventually become soft, spongy and shriveled due to water loss. For long-term storage, garlic is best maintained at temperatures of -1°C to 0°C (30°-32°F) with low relative humidity (60-70%). Good airflow is also necessary to prevent any moisture accumulation. Under these conditions garlic can be stored for more than 9 months.

Garlic will eventually lose dormancy, signaled by internal development of the sprout. This occurs most rapidly at intermediate storage temperatures of 5°-18°C (41°-65°F). Garlic odor is easily transferred to other products and should be stored separately. High humidity in the storages will favor mold growth and rooting. Mold growth can also be problematic if the garlic has not been well cured before storing.


60 to 70 %

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Rates of Respiration Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C (68°F)ml CO2/kg·hrIntact bulbs 2 - 6 4 - 12 6 - 18 7 - 15 7 - 13Fresh peeled cloves 12 15 - 20 35 - 50

To calculate heat production multiply ml CO 2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.


Garlic produces only very low amounts of ethylene (<0.1 µ/kg·hr)


Not sensitive to ethylene exposure.


Atmospheres with high CO2 (5-15%) are beneficial in retarding sprout development and decay during storage at 0-5°C. Low O2 alone (0.5%) did not retard sprout development of 'California Late' garlic stored up to 6 months at 0°C. Atmospheres with 15% CO2 may result in some yellow translucent discoloration occurring on some cloves after about 6 months


Freeze injury. Due to its high solids content, garlic freezes at temperatures below -1°C (30°F).

Waxy breakdown is a physiological disorder that affects garlic during latter stages of growth and is often associated with periods of high temperature near harvest. Early symptoms are small, light yellow areas in the clove flesh that darken to yellow or amber with time. Finally the clove is translucent, sticky and waxy, but the outer dry skins are not usually affected. Waxy breakdown is commonly found in stored and shipped garlic but rarely in the field. Low oxygen levels and inadequate ventilation during handling and storage may also contribute to development of waxy breakdown.


Penicillium rots (Pencillium corymbiferum and other spp.) are common problems in stored garlic. Affected garlic bulbs may show little external evidence until decay is advanced. Affected bulbs are light in weight and the individual cloves are soft and spongy and powdery dry. In an advanced stage of decay, the cloves break down in a green or gray powdery mass. Low humidity in storage retards rot development. Less common storage decay problems include Fusarium basal rot (Fusarium oxysporum

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cepae) which infects the stem plate and causes shattering of the cloves, dry rot due to Botrytis allii, and bacterial rots (Erwinia spp., Pseudomonas spp.).


To control sprout development and lengthen the storage period, garlic may be treated with preharvest applications of sprout inhibitors (i.e., maleic hydrazide) or be irradiated after harvest. Outer cloves of bulbs are easily damaged during mechanical harvest and these damaged areas discolor and decay during storage. Therefore high quality garlic for the fresh market is usually harvested manually to avoid mechanical damage.

Curing garlic is the process by which the outer leaf sheaths and neck tissues of the bulb are dried. Warm temperatures, low relative humidity, and good airflow are conditions needed for efficient curing. Under favorable climatic conditions in California, the garlic is usually cured in the field. Curing is essential to obtain maximize storage life and have minimal decay.

Garlic flavor is due to the formation of organosulfur compounds when the main odorless precursor alliin is converted by the enzyme alliinase to allicin and other flavor compounds. This occurs at low rates unless the garlic cloves are crushed or damaged. Alliin content decreases during storage of garlic bulbs, but the effect of time, storage temperatures and atmospheres has not yet been well documented.

Green Asparagus

Maturity Indices

Asparagus spears are harvested as they emerge through the soil from the underground crowns. Typically, spears are cut when they reach approximately 23cm (9 in.). Stalk diameter is not a good indicator of proper maturity and associated tenderness. (See Quality Indices)

Quality Indices

Quality, fresh asparagus will be dark green and firm with tightly closed, compact tips. Stalks are straight, tender and glossy in appearance.

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U.S. grades are No. 1 and No. 2. California grades range from small (0.47cm / 3/16 in.) to Jumbo (2.1cm / 13/16) but diameter is not a good indicator of tenderness quality. Washington state standards, XF (Extra Fancy), are being adopted that specify tolerances which are somewhat more stringent than U.S. No. 1.

Optimum Temperature

0°-2°C (32°-35.6°F)

Storage life is typically 14-21 days at 2°C and can be extended up to 31 days by 7-10 days storage at 0°C and atmospheric modification. Extended storage (~10-12 days) in air at 0°C may cause chilling injury.


95-100%; High relative humidity is essential to prevent dessication and loss of glossiness. Drying of the butt-end of spears is a negative quality factor. Commonly asparagus is packed and shipped in cartons with a water-saturated pad to maintain high humidity.

Rates of Respiration Temp. °C °F

ml CO2/kg·hr

0 32 14-40 5 41 28-68 10 50 45-152 15 59 80-168 20 68 138-250 25 77 250-300



< 0.1µl/kg·hr at 20°C (68°F)


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Exposure to ethylene will accelerate the lignification (toughening) of asparagus spears in controlled studies. The concentration and duration of exposure to exogenous ethylene, to cause this effect, at commonly encountered levels during storage and distribution are not available.


Elevated CO2 at 5-10% (typically 7%) in air is beneficial in preventing decay and reducing the rate of toughening of the spears. The beneficial effect is most pronounced if temperatures cannot be maintained below 5°C (41°F). Short (CA) exposure to higher CO2

concentrations (12-20%) is safe and beneficial only if temperatures can be maintained at 0° - 1°C (32° - 33.8°F).

Signs of CO2 injury are small to elongated pits, generally first observed just below the tips. Severe injury results in ribbiness.

Physiological Disorders Asparagus will continue to develop after harvest which is why low temperature

postharvest management is critical. Common disorders include upward bending of tips away from gravity and "feathering" (expansion and opening) of tips. Bending will also occur if tips expand to the top of the packaging and are deflected.

Spear toughening occurs rapidly at temperatures above 10°C ( 50°F). Bruising and tip-breakage are signs of rough handling and can result in

toughening of the spears from wound ethylene. Asparagus is sensitive to chilling injury after 10 days at 0°C (32°F). Symptoms of

chilling injury include loss of sheen or glossiness and graying of the tips. A limp, wilted appearance may be observed. Severe chilling injury may result in darkening near tips in spots or streaks

Freezing injury (water-soaked appearance leading to extreme softening) will likely result at temperatures of -0.6°C (30.9°F) or lower.


The most prominent postharvest disease concern is bacterial soft rot, induced by Erwinia carotovora subsp.carotovora. Decay may initiate at the tips or the butt end. Spears that are re-cut above the white portion of the butt end are reported to be most susceptible to bacterial decay.


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Rapid hydrocooling soon after harvest is strongly recommended. Pyramid-shaped wooden or waxed corrugated boxes for hydrocooling combined with center-loading during shipment promote good cooling-air circulation

Jackfruit

Maturity Indices

Jackfruits can reach very large size (as much as 90 cm long, 50 cm wide, and 25 kg in weight), depending on the cultivar, production area, and the fruit load on the tree. Color change from green to yellow to brown is used as an indication of maturity and ripeness stages. Optimum harvest for long-distance transport is when the fruit changes color from green to yellowish-green. Fruits are harvested with a portion of the stalk attached to be used in handling them.

Quality Indices

Fruit size, shape, color, and freedom from defects (sunburn, cracks, bruises) and decay.

Jackfruits contain 25-30% carbohydrates (fresh weight basis) including about 15-20% starch in unripe fruits that is converted to sugars (sucrose + glucose + fructose) in ripe fruits.

The unripe fruit is used as a starchy vegetable, either boiled or roasted, and when ripe it is used as a dessert fruit. Average acidity is 0.25% citric acid.

Jackfruit fruitlets are commonly sold in producing countries as a fresh-cut product.

Optimum Temperature

13 ± 1°C (56 ± 2°F); potential postharvest-life = 2-4 weeks, depending on cultivar and maturity stage.


85-95%


20-25 (preclimacteric) to 50-55 (climacteric peak) ml CO2/kg·hr at 20°C (68°F)



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No published information.


Exposure to 100ppm ethylene for 24 hours accelerates ripening of mature-green jackfruits at 20-25°C (68-77°F). During ripening, the starch is converted into sugars, the pulp color changes from pale white or light yellow to golden yellow, and the fruit aroma becomes intense.




Chilling Injury: Jackfruits exposed to temperatures below 12°C (54°F) before transfer to higher temperatures exhibit chilling injury symptoms, including dark-brown discoloration of the skin, pulp browning and off-flavor development, and increased susceptibility to decay.


Pathological disorders usually follow mechanical and/or chilling injuries. No published information on postharvest pathogens of jackfruits.

Mushroom

Maturity Indices

Agaricus bisporus mushrooms (Button Mushrooms) are harvested by maturity and not by size. Maturity is reached when the caps are well- rounded and the partial veil is completely intact. The stipe (stalk) should have a small length to thickness ratio. Stipe length should be sufficient to permit some trimming without cutting flush to the veil.

Quality Indices

Good quality, fresh ‘Agaricus' mushrooms should be white to dark brown. White forms are most prevalent. Uniform, well rounded cap with a smooth glossy surface and fully intact veil are indicators of best quality. Stipes are straight and glossy in appearance with an even cut edge. Cleanliness (minimal growth medium residue) and absence of browning or other discoloration are additional quality factors. Visible, open gills and absence of a stipe are negative factors.

U.S. grades are No. 1 and No. 2. Sizes range from Small {Button} ( 1.9 - 3.2cm / .75 - 1.25 in. ), Medium ( 3.2 - 4.5cm / 1/25 - 1.75 in.), to Large ( 4.5 cm / 1.75 in. and larger)

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measured as cap diameter. Grades discriminate for maturity, shape uniformity, cleanliness and trim quality.

Optimum Temperature

0° - 1.5°C ( 32° - 35°F ) Storage life is typically 5-7 days at 1.5°C(35°F) and 2 days at 4.5°C (40°F).


95-98 %; High relative humidity is essential to prevent desiccation and loss of glossiness. Drying is correlated with blackening of the stipe and gills and curling of the cap. Commonly mushrooms are packed and shipped in cartons with a perforated overwrap to maintain high humidity.


Temperature °C °F

ml CO2/kg·hr

0 32 14-22

5 41 35

10 50 50

15 59 NA

20 68 132-158

25 77 NA

To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day. NA= not applicable


>0.1µl / kg·hr at 20°C (68°F)


Agaricus mushrooms are not significantly impacted by exogenous ethylene.


Extended storage ( ~12-15 days ) in 3% O2 and 10% CO2 at 0°C has been Controlled demonstrated. Elevated CO2 at 10-15 % ( typically 10% ) in air is beneficial in Atmosphere (CA) preventing decay and reducing the rate of blackening of the stipe and gills. The beneficial effect is most pronounced if temperatures cannot be maintained below 5°C ( 41°F ). Short exposure to higher CO2 concentrations (20 %) is safe and beneficial only if temperatures can be maintained at 0° - 1°C (32° - 34°F).

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Improper control of controlled atmospheres or improper packaging can rapidly lead to depletion of oxygen resulting in conditions favorable for Clostridium botulinum. For this reason, primarily, the use of CA and MA is not common.


Mushrooms will continue to develop after harvest which is why low & Physical temperature postharvest management is critical. Common disorders include Disorders upward bending of caps and opening of the veil.

Mushrooms are easily bruised by rough handling and develop patches of browning discoloration.

Freezing injury ( water-soaked appearance leading to extreme softening ) will likely result at temperatures of -0.6°C ( 30.9°F) or lower.

Signs of CO2 injury are blackening and pitting.


Disease is generally not an important source of postharvest loss in comparison with physiological senescence and improper handling or bruising. Diseases, such as Bacterial Blotch, and spoilage due to other Pseudomonas spp. are generally eliminated during the harvest or sorting phases although development of patches of decay can occur with elevated temperature or extended storage.


Rapid forced-air cooling soon after harvest is strongly recommended. Center-loading during shipment promotes good cooling-air circulation necessary for this commodity. Good arrival following surface transportation is enhanced when trailers are equipped with ‘air-shocks' suspension. Agaricus mushrooms are reported to acquire strong odors, such as onion, in mixed loads or short term storage.

Lettuce: Crisphead or Iceberg

Maturity Indices

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Maturity is based on head compactness. A compact head which can be compressed with moderate hand pressure is considered ideal maturity. A very loose head is immature and a very firm or hard head is overmature. Heads that are immature and mature have much better flavor than overmature heads and also have fewer postharvest problems.

Quality Indices

After trimming outer wrapper leaves, the leaves should be a bright light green color. Leaves should be crisp and turgid.


0°C (32°F) with >95% RH are required to optimize lettuce storage life. A shelf-life of 21-28 days can be expected at this temperature and RH. At 5°C (41°F) a shelf-life of 14 days can be expected as long as no ethylene is in the environment. Vacuum cooling is usually used for iceberg lettuce, but forced-air cooling may also be used successfully.

Freezing Injury

Freeze damage can occur in the field and cause separation of the epidermis from the leaf. This weakens the leaf and leads to more rapid bacterial decay. During storage, freeze damage can occur if the lettuce is stored at <-0.2°C (31.7°F). This appears as a darkened translucent or water-soaked area which will turn slimy and deteriorate rapidly after thawing.


Iceberg lettuce heads have moderate respiration rates

Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C (68°F) ml CO2/kg·hr 3-8 6-10 11-20 16-23 25-30

To calculate heat of production multiply ml CO2/kg·hr by 440 to get Btu/ton-day or by 122 to get kcal/metric ton-day.

Rates of Ethylene Production Very low, <0.1 µL/kg·hr at 20°C (68°F).

Responses to Ethylene Iceberg lettuce is extremely sensitive to ethylene. Russet spotting (see physiological disorders) is the most common symptom of ethylene exposure.


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Some benefit to shelf-life can be obtained with low O2 atmospheres (1-3%) at temperatures of 0-5°C (32-41°F). Low O2 atmospheres will reduce respiration rates and reduce the detrimental effects of ethylene. Intact heads are not benefitted by atmospheres containing CO2 and injury may occur with >2% CO2 (see physiological disorders, brown stain). Lettuce cut for salad products, however, is commonly packaged in low O2(<1%) and high CO2 (10%) atmospheres because these conditions control browning on the cut surfaces. On salad pieces, cut surface browning occurs more rapidly and more extensively than do symptoms of brown stain caused by CO2.


Many disorders have been identified for iceberg lettuce. Some very common and important disorders are the following:

Tipburn. A disorder caused in the field and is related to climactic conditions, cultivar selection and mineral nutrition. Leaves with tipburn are unsightly and the damaged leaf margins are weaker and susceptible to decay.

Russet Spotting. A common disorder due to exposure to low concentrations of ethylene which stimulates the production of phenolic compounds which lead to brown pigments. Russet spots appear as dark brown spots especially on the midribs. Under severe conditions, russet spots are found on the green leaf tissue and throughout the head. The disorder is strictly cosmetic but makes the lettuce unmarketable. Ethylene contamination may occur from propane fork lifts, transport in mixed loads, or storage with ethylene-generating fruits such as apples, pears and peaches.

Brown Stain. The symptoms of this disorder are yellowish-reddish-brown large, depressed spots on the midribs mostly. These may darken or enlarge with time. Brown stain also appears as reddish-brown streaks in some cases. Brown stain is caused by exposure to above 3% CO2 atmospheres, especially at low temperatures.

Pink rib. A disorder in which the midribs take on a pinkish coloration. Overmature heads and high storage temperatures increase the disorder. Ethylene exposure does not increase the disorder and low O2 atmospheres do not control it.

Physical Disorders

Breakage of the midribs often occurs during field packing and causes increased browning and increased susceptibility to decay.


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Bacterial soft-rots are caused by numerous bacteria species and result in a slimy breakdown of the infected tissue. Soft-rots may follow fungal infections. Trimming outer leaves, rapid cooling and low temperature storage reduce development of bacterial soft-rots.

Fungal pathogens. May also lead to a watery breakdown of lettuce (watery soft-rot caused by Sclerotinia or gray mold rot caused by Botrytis cinerea) but are distinguished from bacterial soft-rots by the development of black and gray spores. Trimming and low temperatures also reduce the severity of these rots.

Okra

Maturity Indices

Okra pods are immature fruits and are harvested when they are very rapidly growing. Harvest typically occurs 3 to 7 days after flowering. Okra should be harvested when the fruit is bright green, the pod is fleshy and seeds are small. After that period, the pod becomes pithy and tough, and the green color and mucilage content decrease.

Quality Indices

Okra pods should be tender and not fibrous, and have a color typical of the cultivar (generally bright green). The pods should be well formed and straight, have a fresh appearance and not show signs of dehydration. Grade is U.S. no. 1. Pods are packed based on length with Fancy, Choice and Jumbo designations for size categories. Okra should be free of defects such as leaves, stems, broken pods, insect damage, and mechanical injury. The tender pods are easily damaged during harvest, especially on the ridges and this leads to unsightly brown and black discoloration. Quality losses that occur during marketing are often associated with mechanical damage, water loss, chilling injury, and decay.

Optimum Storage Temperature

7-10°C (45-50°F) Very good quality can be maintained up to 7 to 10 days at these temperatures. If stored at higher temperatures, the pods lose quality due to dehydration, yellowing and decay. When stored at lower than recommended temperatures, chilling injury will be induced (see physiological disorders). Chilling symptoms include surface discoloration, pitting and decay. Okra can be successfully hydrocooled or forced-air cooled.


Weight loss is very high in immature okra pods and cultivars may vary in rate of water loss. A very high relative humidity (95-100%) is needed to retard dehydration, pod toughening, and loss of fresh appearance.

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Okra pods have very high respiration rates.

Temperature 5°C (41°F) 10°C (50°F) 15°C (59°F) 20°C (68°F)

ml CO2>/kg·hr 27 - 30 43 - 47 69 - 72 124 - 137


Rates of Ethylene Production and Responses to Ethlylene

Okra pods have low ethylene production rates (<0.5 µL/kg·hr at 10°C). Exposure to ethylene reduces shelf-life by increasing pod yellowing.


Okra is not stored in modified atmospheres commercially. At recommended storage temperatures, CO2 concentrations of 4-10% can help maintain green color and reduce discoloration and decay on damaged pods. CO2 concentrations higher than 10% can lead to off flavors. Low O2 concentrations (3-5%) reduce respiration rates and may also be beneficial.


Chilling injury: The typical symptoms of chilling injury in okra are discoloration, pitting, water-soaked lesions and increased decay (especially after removal to warmer temperatures, as during marketing). Different cultivars may differ in their susceptibility to chilling injury. Calcium dips and modified atmospheres have been reported to reduce chilling symptoms.

Freeze damage: occurs at temperatures of -1.8°C (28.7°F) or below.


Decay on okra can be due to various common bacterial and fungal organisms, but chilling and injury-enhanced rots are probably the most common causes of loss. Rhizopus, Geotrichum and Rhizoctonia fungal rots as well as bacterial decays due to Pseudomonas sp. have been reported to cause postharvest losses.

Onion: Dry

Maturity Indices Indicated when approximately 10 to 20 percent of tops have fallen over

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Conversion from active growth to dormancy accelerated by undercutting bulbs 1 to 2 inches

"Field-dry" maturity is indicated when bulb neck is completely dry to the touch and not slippery. Typically reached at 5-8% weight loss following harvest.

Quality Indices Mature neck and scales Firmness Diameter (Bulb size) Absence of decay, insect damage, sunscald, greening, sprouting, freezing injury,

bruising, and other defects Degree of pungency

Optimum Temperature

Curing. Field curing when temperatures are at least 24°C(75°F) or exposure for 12 hrs. to 30 to 45°C (86 to 113°F) for forced air-curing. Storage. Mild onions: Typically 0.5 to 1 month at 0°C(32°F) Pungent Onions: Typically up to 6 to 9 months at 0°C(32°F) depending on the cultivar


Curing. 75 to 80% for best scale color development Storage. 65 to 70% with adequate air circualtion (1m3/min/ m3 of onion )

Rates of Respiration Whole Onions- 3-4 ml/kg·hr @ 0-5°C (32-41°F); 27-29 ml/kg/hr @ 25-27°C(75-

79°F). Storage between 5-25°C(41-75°F) favors sprouting and is not recommended for extended periods.

Diced Onions- 40-60 ml/kg·hr @ 0-5°C(32-41°F)

To calculate heat production multiply ml CO2/kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton/day.


Whole Onions: < 0.1 µl/kg·hr at 0-5°C (32-41°F) Diced Onions: NA


Ethylene may encourage sprouting and growth of decay-causing fungi.


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No commercial benefit has been identified for varieties with long storage potential. Onions are damaged by < 1% O2 and 10% CO2. There is some commercial use of CA (3% O2and 5-7% CO2) for sweet onion varieties (short storage potential) . Diced onions benefit from CA conditions of 1.5% O2 and 10% CO2.

Physiological Disorders Freezing Injury. Soft water-soaked scales rapidly decay from subsequent

microbial growth. Translucent Scales. Resembles freezing injury and is prevented by prompt cold

storage following curing; 3-4 week delay in cold storage increases risk significantly.

Greening. Exposure to light following curing causes green-coloration of outer scales.

Ammonia Injury. Brown-black blotches result from ammonia gas leakage during storage.


Botrytis Neck Rot. Watery-decay initiates at neck area and moves downward through entire bulb. Light gray to Gray fungal growth is generally visible at neck infection and on outer scales. Proper drying and curing of onion essentially prevents this storage disorder. Storage conditions (as above) should be maintained to prevent condensation from forming on the bulbs.

Black Mold. Black discoloration and shriveling at neck and on outer scales caused by the fungus Aspergillus niger. Often associated with bruising and leads to bacterial soft rot. Low temperature storage will delay growth of fungus following field or handling infestation but growth will resume above 15°C (59°F).

Blue Mold. Watery soft rot of neck and outer scales followed by the appearance of green-blue mold (occasionally yellow-green) spores of the fungus Penicillium. Minimize bruising and other mechanical injuries, sunscald, and freezing injury.

Bacterial Rots/Soft Rot . Water-soaked, foul-smelling, viscous liquidy rot caused by Erwinia carotovora subsp. carotovora. Slippery Skin: Generally visible only at neck area and upon cutting to expose inner scales. Scales have a watery-cooked appearance. Sour Skin: Slimy, yellow-brown decay generally limited to inner scales which give off a sour odor when exposed.

General Bacterial Rot Control:

1. Harvest only at full maturity 2. Proper drying and curing 3. Minimizing bruising and scraping;

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4. Maintaining proper storage conditions (as above) to prevent condensation from forming on the bulbs.


Onions are both storage-odor sources for other commodities, such as apples, celery and pears, and storage-odor absorbers from commodities such as apples.

Onion: Green Bunching

Maturity Indices

Maturity of green onions is determined primarily by size which is largely determined by seeding density. Green or "bunching" onions are selected varieties of white onion (Allium cepa) planted at high density or from the non-bulbing onion group (Allium fistulosum) generally called Japanese-bunching. Harvest maturity is generally accepted as mean diameter of 0.6 to 1.3 cm (1/4 to 1/2 inch) in diameter at the base plate of the immature bulb.

Quality Indices

Quality green onions have a thin, white shank or neck at least 5 to 7.5 cm (2-3 inches) in length. Green onions should be well-formed (at most slightly curved or angular), uniform in shape, thin-necked, turgid, bright in color, well cleaned, and free from excessive roots, decay, insect-injury, mechanical damage, broken or crushed leaves, or dehydrated clipped-ends.

U.S. Grade No. 1, No. 2 (Standards established June 1947)

Optimum Storage

0°C (32°F); > 98% R.H.

Green onions held at 32°F and 98 to 100 % relative humidity will remain fresh and flavorful for up to 4 weeks. Green onions are highly perishable and normally marketed over a short period. Lowering and removing the heat of respiration as well as preventing water loss is critical. Package-icing and perforated polyethylene film liners are used to maintain quality. Typically, storage life of green onions at 10°C (50°F) is 7 to 10 days. Higher temperatures greatly accelerate yellowing and decay of the leaves. Green onions benefit from light misting.


Temperature ml CO2/ kg·hr °C °F

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0 32 5-165 41 9-1910 50 18-3115 59 33-5820 68 40-9025 77 49-105

§ To calculate heat production, multiply ml CO2 / kg · hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day.


<0.1 µl/kg·hr at 20°C (68°F)


Green onions are not sensitive to external ethylene.


Information varies widely on the optimal conditions and extent of benefit of CA for green onions. In general, a controlled atmosphere of 2 % oxygen with 5% carbon dioxide at 0°C (32°F) should allow 6 to 8 weeks storage. Visually, green onions tolerate 1% O2 and 10% CO2 but off-flavors have been associated with extended storage above 5°C (41°F).


Freezing Injury. Freezing injury will be initiated at -1.0°C (30.6°F). Symptoms of freezing injury include a water-soaked appearance of bulb or leaves and wilted or gelatinous leaves, after thawing. The bulb will become soft or gelatinous in texture in outer tissue. Freeze-injury is rapidly followed by bacterial soft-rot decay.

Curvature. Upward bending of young, elongating shoots will occur in horizontally packed green onions. Prompt cooling and storage at 0°C (32°F) will largely prevent this defect. CA-packaging can further retard curvature (See Responses to CA).

Physical Injury

Harvesting, trimming, and banding should be done gently to prevent crushing or other injuries. At harvest, pulling is usually done without undercutting. Bunching is done in the field or in a packing shed. Bruising is common and leads to rapid decay when attention to rapid cooling (within 3 hours of harvest) and cold chain control are not applied.


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Diseases may be an important source of postharvest loss in combination with rough handling and poor temperature control. Common diseases are Bacterial Soft-Rot (primarily Erwinia carotovora and Pseudomonas spp) and Grey Mold (Botrytis cinerea). Grey Mold is often associated with barely visible preharvest injury to tender foliage by chemical applications or ozone injury from air pollution.


Odor. Green onions produce odors that may be adsorbed by many other commodities such as apples, grapes, and mushrooms.

Package-Ice used for transportation of green onions has been implicated on several occasions as the cause of outbreaks of food-borne illness due to the pathogens Shigella, Cryptosporidium, and others. Water quality and hygienic handling of ice is essential.

Proper selection of packaging films together with proper temperature management can greatly extend the shelf-quality of green onions trimmed or prepared for bulk ready-to-use format.

Pepino

Maturity Indices

Pepino dulce (Solanum muricatum Ait.) should be harvested when ripe (yellow) to have the best flavor quality. Skin color changes with ripening from green to pale white to cream to yellow (with purple stripes). Pepinoes soften as they ripen.

Quality Indices Fruit shape varies from round to elongate and length varies from 5 to 20cm,

depending on cultivar and number of fruit/plant. Skin color (yellow to golden-yellow) and flesh color (light orange). Freedom from defects (such as sunburn and bruising) and decay. Juiciness (more than 40% juice) Sweetness (soluble solids range from 6-12%; minimum acceptability at 10% or

higher. Titratable acidity is low (0.04-0.10%); citric acid is predominant. Vitamin C content varies among cultivars from 30 to 70mg/100g fresh weight.

Optimum Temperature

7.5-10° C (45-50°F); storage potential = 4-6 weeks, depending on cultivar and ripeness stage.


90-95%

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8-12ml CO2/kg·hr at 20°C (68°F); non-climacteric respiratory pattern

To calculate heat production multiply ml CO2 /kg·hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.


Less than 0.1 ml/kg·hr at 20°C (68°F)


Exposure to 10-100ppm ethylene stimulates chlorophyll degradation (loss of green color) and respiration rate of mature-green pepino fruit, but has no effect fully ripe (yellow) fruit.




Chilling injury. Storing pepinoes at temperatures below 7.5°C (45°F) for two weeks or longer, depending on temperature, will result in chilling injury. Symptoms develop upon transfer to higher temperatures and include pitting, skin browning, and flesh browning. Ripe pepinoes are less sensitive to chilling injury than partially-ripe or mature-green fruit.


Alternaria Rot. Pepino fruit, especially when chilled, are susceptible to Alternaria Rot caused by Alternaria solani. Symptoms include dark-brown to black spots beginning at the stem end and expanding to the rest of the fruit. Control strategies include minimizing mechanical injuries during harvesting and handling and avoiding chilling injury and water stress by maintaining the optimum ranges of temperature and relative humidity throughout the handling system.

Pumpkin & Winter Squash

Maturity Indices

Corking of the stem and subtle changes in rind color (bright green to dull green in ‘Kabocha’ for example) are the main external indications of maturity. Immature fruit

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have a fleshy stem, maturing fruit will have some stem corking, and well mature fruit will have a well corked stem. Internal color should be intense and typical of the cultivar. The concentrations of the yellow and orange carotenoids generally increase only slightly during storage. Maturity at harvest is the major determinant of internal color. Immature fruit will be of inferior eating quality because they contain less stored carbohydrates. Immature fruit will have more decay and weight loss during storage than mature fruits.

Quality Indices

Pumpkin and winter squash should be full sized and well formed with the stem intact. They should be well matured with good rind development typical of the cultivar. Internal quality attributes are high color due to a high carotenoid content, and high dry weight and sugar and starch contents.

Optimum Temperature

12.5-15°C (55-59°F) Pumpkins and winter squash are very chilling sensitive when stored below 10°C (50°F). Depending on the cultivar a storage life of 2 to 6 months can be expected at 12.5-15°C (55-59°F). Recent research at Oregon State University showed that for 8 currently produced winter squash cultivars stored at 10-15°C (50-59°C), 90%, 70% and 50% were marketable after 9, 15 and 20 weeks, respectively. For green rind squashes, storing at 15°C (59°F) may cause degreening, undesirable yellowing, and texture loss. The green rind squashes can be stored at 10-12°C (50-55°F) to prevent degreening, although some chilling injury may occur at the lower temperature. High storage temperature (>15°C) will result in excessive weight loss, color loss and poor eating quality.


50-70% with 60% usually considered optimum Moderate relative humidity with good ventilation is essential for optimum storage. High humidity will promote decay. Although 50-70% RH will reduce decay during storage, significant weight loss will occur. For example, mature Kabocha squash lose 1.0 and 1.5% of their fresh weight per week of storage at 12.5°C (59°F) and 20°C (68°F), respectively.


30-60 ml CO2 / kg·hr at 25°C (77°F) § To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day.


<0.5µL C2H4 /kg·hr at 20°C. If the fruit are chilled, ethylene production rates can be 3-5 times higher.

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Exposure to ethylene will degreen squash with green rinds. Ethylene will also cause abscission of the stem, especially in less mature fruit.


Atmospheres containing 7% CO2 can be beneficial by reducing loss of green color. Yellow squash, however, appear not to be benefited by 5 or 10% CO2 atmospheres. Lowering the O2 concentration does not appear to provide any benefit.


Chilling injury. Caused if pumpkins and squashes are stored below 10-12.5°C (50-55°F). Symptoms of chilling injury are sunken pits on the surface and high levels of decay once fruit are removed from storage. Storing fruit 1 month at 5°C (41°F) is sufficient to cause chilling injury symptoms. Depending on the cultivar, storage for several months at 10°C (50°F) may cause some chilling injury.

Freezing injury. Can occur at temperatures below -0.8°C (30.5°F).


Several fungi are associated with decay during storage of pumpkins and winter squashes. Fusarium, Pythium and anthracnose (Colletotrichum) and gummy stem blight or black rot (Mycosphaerella) are common fungi. Alternaria rot will develop on chill-damaged winter squashes. Fruit that are overmature at harvest (>2 weeks beyond optimal harvest date) will tend to have more storage decay.


Curing. The fruits may have tender rinds when freshly harvested. Curing in the field (with protection from the sun by placing under the leaves) before handling and stacking into bins or wagons will help to harden or cure the rind. The recommended storage conditions also favor curing or hardening of the rind.

Quince

Maturity Indices

Change of skin color from green to yellow is the primary maturity index. Quinces should be picked when full-yellow and firm.

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Quality Indices Size, color, freedom from defects and decay. Quinces must be handled carefully as they bruise easily. Quinces are not eaten fresh because of their astringency (due to high tannin

content).

Optimum Temperature

0°C (32°F)Highest freezing point = - 2°C (28.4°F) Storage potential = 2-3 months


90-95%


Climacteric respiratory pattern.

Temperature 0°C (32°F) 10°C (50°F) 20°C (68°F)ml CO2/kg·hr 2.3 - 5.2 10.2 - 14.1 21.2 - 39.0


Rates of Ethylene Production Temperature 0°C (32°F) 10°C (50°F) 20°C (68°F)

µl C2H2kg·hr 2.3 - 6.1 6.9 - 7.4 11.0 - 31.9


Ethylene (100ppm) treatment for 2 days at 18-21°C (65-70°F) and 90-95% relative humidity can be used after removal from cold storage to stimulate more uniform and faster ripening of quinces before processing.



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Blue mold, caused by Penicillium expansum, is the most common postharvest disease of quinces. Control strategies include careful handling to minimize wounding, prompt cooling to 0°C (32°F), and maintenance of optimum temperature and relative humidity during storage.

Radish

Maturity Indices

Radish (Raphanus sativus L.) is a diversely formed root vegetable and has many uses worldwide. Red and icicle radish are most common but Asian "daikon" types are increasing in popularity outside of countries such as Korea, Japan, Taiwan and China. The number of days post-seeding or emergence, which may vary from 30 to 70 days, depending on type, typically determines maturity. A minimum size standard for common red radish is 5/8 inch (1.6cm) equatorial diameter. Current crop management practices stress rapid growth to ensure a mild flavor and crisp texture. Fertilization and irrigation management, or environmental conditions that slow growth may result in a woody texture and high pungency. Over-mature radish tends to be pithy (vacuolated) or spongy in texture and may develop harsh flavors, for most palates.

Quality Indices

Roots of Bunched or Topped Common Red Radish should, ideally, be of uniform and similar shape for the variety, well formed, smooth, firm but of tender texture, and free of growth or harvest damage, and free of decay, disease or insects. Bunched radish tops should be fresh in appearance, turgid, and free of freeze injury or other serious injury, seed stalk, yellowing or other discoloration, disease, decay, or insects

U.S. Grade Standards effective October 1968 includes U.S. No. 1 and Commercial

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Optimum Temperature

32°F (0°C). Rapid cooling is essential to achieve the full storage potential of both bunched and topped roots. Radish is often top-iced to maintain temperature and contribute moisture for retaining a crisp texture. Under these conditions common red radish may be expected to maintain acceptable quality for 7 to 14 days with tops and 21 to 28 days if topped. Daikon-type radish may last from 3 to 4 months at these same conditions.


95 - 100%


Common Red Radish

Temperature 0°C (32°F) 5°C (41°F) 10°C (50°F) 20°C (68°F)ml CO2/kg·hrBunched 6 - 7 8 - 9 14 - 16 58 - 62Topped 2 - 4 3 - 5 6 - 7 19 - 26



Very low; <0.1 mL/kg·hr at 20°C


Not Sensitive. Bunched tops may exhibit yellowing with prolonged storage and ethylene exposure.


Atmospheres of 1 to 2% O2 and 2 to 3 % CO2 are slightly beneficial in maintaining quality of topped radish when storage temperatures are 5 to 7°C (41 to 45°F). CA helps retard the re-growth of shoots and rootlets in "topped and tailed" roots. Even short exposure to temperatures above 7°C (45°F) will result in the development of off-flavors, browning, and soft-rot.


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Freeze injury. As radish is, ideally, stored and transported just above the freezing point (30.5°F/ -1.0°C), freeze injury is not uncommon. Shoots become water-soaked, wilted, and turn black. Roots appear water-soaked and glassy, often only at the outer layers if the freezing temperature is not too low. Roots become soft quickly on warming and pigmented roots may "bleed" (lose pigment).


Bacterial Black Spot. (Xanthomonas campestris pv. vesicatoria) is a problem in some production locations and will develop in postharvest storage at warmer than optimum temperatures. Refrigeration is the primary control but washing roots in chlorinated water is reported to significantly control this disease.

Prompt cooling, chlorination, and refrigeration are also effective in controlling Bacterial Soft Rot (Erwinia carotovora subsp carotovora).

Rhizotonia spp. lesions may develop in storage at warmer than optimal temperatures but is more effectively controlled in the field. Botrytis (Grey Mold) and Sclerotinia (Watery Soft Rot) can develop, especially around harvest wounds, even at temperatures below 5°C (41°F) but is not common on radish in the U.S.

Snap Beans

Maturity Indices

Snap beans (yellow, green and purple types) are harvested when they are rapidly growing and developing. Harvest occurs about 8-10 days after flowering for typical mature snap beans. Beans should be harvested when the fruit is bright green, the pod is fleshy and seeds are small and green. After that period, seed development reduces quality and the pod becomes pithy and tough and looses green color.

Quality Indices

Beans should be well formed and straight, bright in color with a fresh appearance, and tender but firm. They should snap easily when bent. Leaves, stems, broken beans, blossom remains, insect damage should not be present. Decreased quality during postharvest handling is most often associated with water loss, chilling injury, and decay.

Optimum Temperature and Relative Humidity (RH)

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5-7.5°C (41-45°F) and 95-100% (RH) Very good quality can be maintained for a few days at temperatures below 5°C but chilling injury will be induced (see physiological disorders). Some chilling may occur even at the recommended storage temperature of 5°C after 7-8 days. At 5-7.5°C (41-45°F) a shelf-life of 8-12 days is expected.

Water loss is a common postharvest problem with green beans. About 5% weight loss is needed before shrivel and limpness are observed. After 10-12% weight loss, the beans are no longer marketable. The weight loss of mature green beans can be estimated from the equation: % weight loss per day = 0.754 x vapor pressure deficit. The VPD can be obtained from a psychrometric chart when temperature and relative humidity are measured. The rate of water loss of immature beans is higher than for mature beans.


Temperature ml CO2>/kg·hr

°C °F Snap Beans Long beans

0 32 10 20

5 41 17 23

10 50 29 46

15 59 46 101

20 68 65 110

To calculate heat production, multiply ml CO2/kg· hr by 440 to get BTU/ton× day or by 122 to get kcal/metric ton× day


<0.05 µL/kg·hr at 5°C (41°F)


Exposure to ethylene at usual storage temperatures causes loss of green pigment and increased browning. Concentrations above 0.1 ppm reduce green bean shelf-life by 30-50% at 5°C .


At recommended storage temperature, O2 concentrations of 2-5% reduce respiration rates. Snap beans tolerate and are benefited by CO2 concentrations between 3-10%. The main benefit is retention of color and reduced discoloration on damaged beans. Higher CO2 (20-30%) concentrations can be used for short periods, but can cause off-flavors.

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Chilling injury. The typical symptom of chilling injury in beans stored <5°C (<41°F) for longer than 5-6 days is a general opaque discoloration of the entire bean. A less common symptom is pitting on the surface. The most common symptom of chilling injury is the appearance of discrete rusty brown spots which occur in the temperature range of 5-7.5°C (41-45°F). These lesions are very susceptible to attack by common fungal pathogens. Beans can be held about 2 days at 1°C (34°F), 4 days at 2.5°C (36°F), or 8-10 days at 5°C (41°F) before chilling symptoms appear. No discoloration occurs on beans stored at 10°C (50°F). Different varieties differ significantly in their susceptibility to chilling injury.

Freezing injury. Appears as water-soaked areas which subsequently deteriorate and decay. Freezing injury occurs at temperatures of -0.7°C (30.7°F) or below.


Decay due to various pathogens occurs after beans have been chill damage. Surface decay may also occur on stems and beans if free moisture is present during storage at >7.5 (>45°F). Common postharvest decay organisms on green beans are the fungi Pythium, Rhizopus, and Sclerotinia, all of which may occur as "nests" of decay or on broken or damaged beans.


Haricot Verts. Extra careful handling is required for tender immature green beans or haricot verts to avoid physical damage and dehydration.

Long beans have similar postharvest requirements as green beans and similar responses to chilling temperatures. Long beans may yellow more and have more seed development during postharvest handling than snap bean

Spinach

Maturity Indices

Spinach is selected for size and maximal recovery of clean leaves that are mid-maturity to young. Older and yellowing leaves are avoided when making the harvest cut. Generally 3-4 weeks of re-growth are required before a second harvest will yield adequate volume.

Quality Indices

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Spinach, whether bunched or as leaves, should be uniformly green (generally not yellow-green), fully turgid, fairly clean, and free from serious damage. For bunched spinach, roots should be trimmed short to grade standards and petioles should be predominantly shorter than the leaf blade.

U.S. Grades: Bunched — U.S. No. 1, No. 2 (Oct. 1987) Leaves — U.S. Extra No. 1, No. 1, Commercial (Dec. 1946)

Optimum Temperature

0°C (32°F); 95-98% R.H.

Spinach is highly perishable and will not maintain good quality for more than 2 weeks. Wilting, yellowing of leaves, and decay are likely to increase following storage beyond 10-14 days; faster at common distribution conditions of 5 to10°C(41 to 50°F).

In a 1994 UC Davis study, an average of 17, 28, and 45% of leaves of 16 varieties had decay after 2, 3, and 4 weeks at 5°C, respectively. After the same periods at 5°C, 18, 25, and 45% of the leaves showed some yellowing. Commercial varities such as Imperial Spring, Shasta, Polka, Spectrum and Sporter had notably longer shelf- life than did varieties Bossanova, Spark and Space.

Rates of Respiration Temperature

°C Temperature

°Fml CO2 /

kg·hr

0 32 9-11

5 41 17-29

10 50 41-69

15 59 67-111

20 68 86-143

§ To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day.


< 0.1µl / kg·hr at 20°C (68°F)


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Spinach is highly sensitive to exogenous ethylene. Accelerated yellowing will result from low levels of ethylene during distribution and short-term storage. Do not mix loads such as apples, melons and tomatoes with spinach.


Atmospheres of 7-10% O2 and 5-10% CO2 offer moderate benefit to spinach by delaying yellowing. Spinach is tolerant to higher CO2 concentration but no increase in benefits has been observed. Package film for prewashed spinach leaves is selected to maintain 1-3% O2 and 8-10% CO2 .


Freezing Injury. Freezing injury will be initiated at - 0.3°C (31.5°F). Freezing injury results in watersoaking typically followed by rapid decay by soft-rot bacteria.

Yellowing. Spinach is highly sensitive to exogenous ethylene (See Response to Ethylene).

Physical Injury

Harvesting and handling should be done with care to prevent damage to the petioles and leaves. Bunching ties should not be too tight as crushed or spilt petioles may lead to rapid decay.


Bacterial Soft-Rot (primarily Erwinia and Pseudomonas) is a common problem. Decay is usually associated with damaged leaves and stems.


Package-icing and top-icing loads may be used. Frequent light misting may be done in displays to delay wilting of bunched spinach.

Sweet Potato

General

The sweetpotato (Ipomoea batatas) is a warm season root crop. Moist, sweet flesh types of sweetpotatoes are sometimes called "yams", but these should not be confused with true yams (Dioscorea sp.). Cultivars with high orange-colored flesh contain much higher levels of carotenoids than less pigmented types. Sweetpotato flavor is largely based on

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starch and sugar concentrations, and these are affected by cultivars and storage conditions.

Maturity Indices

Sweetpotatoes are harvested when roots have reached the desirable size. Irrigation is typically stopped 2 to 3 weeks before harvest so that vines begin drying before they are removed and roots are harvested.

Quality Indices

Good quality sweetpotatoes should be smooth and firm, with uniform shape and size, be free from mechanical damage, and have a uniform peel color typical of the variety. There are four U.S. Grades for sweetpotato (U.S. Extra No. 1, U.S. No.1, U.S. commercial and U.S. No. 2), and grades are based on degree of freedom from defects (dirt, roots, cuts, bruises, growth cracks, decay, insects, and diseases), but also size and weight categories.

Optimum Temperature

The recommended conditions for commercial storage are to keep roots cool and dry. Sweetpotato roots are chilling sensitive and should be stored between 12.5°C and 15°C (55°F to 59°F) with high relative humidity (>90%). A storage life of 6-10 months can be expected under these conditions, although sprouting may begin to occur after about 6 months depending on cultivar. Temperatures above 15°C (59°F) lead to more rapid sprouting and weight loss. Careful handling during harvesting will minimize mechanical damage to the skin and reduce decay incidence during storage. Roots are not washed before storing in bins or crates, but only after removal for selection and packing for marketing. Sweetpotato roots are commonly stored in evaporatively cooled rooms, supplemented by mechanical refrigeration late in the storage period when warm ambient temperatures occur.


>95 % for long-term storage; 70-90% for short-term handling for marketing

Rates of Respiration Temperature 10°C (50°F) 15°C (59°F) 25°C (77°F)ml CO2/kg·hrCured 7 10 - 12 ---Noncured --- 15 27 - 35


Rates of Ethylene Production and Responses to Ethylene

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Sweetpotato roots produce very low amounts of ethylene (~0.1 µL/kg·hr), although much higher rates can occur after chilling, wounding and decay development. Exposure to ethylene (1 to 10 ppm) increases respiration rates and phenolic metabolism and adversely affects flavor and color of cooked roots.


There is no commercial use of controlled atmospheres for sweetpotato storage. Respiration rates of roots are reduced as oxygen is lowered from 21 to 3%. Oxygen concentrations below 3% may results in increased respiration rates due to fermentative metabolism. Response of roots to increased carbon dioxide levels is not known.


Chilling injury. Sweetpotato roots are very sensitive to chilling injury at temperatures of 12.5°C (55°F) or below. Symptoms of chilling injury include fungal decay, internal pulp browning, and root shriveling. Chilled roots that have been cooked can have "hardcore" defect and a darker color than non-chilled roots.


Chilling and mechanical injury predispose sweetpotatoes to decay, especially Rhizopus soft rot. Postharvest fungicides may be applied to reduce the risk of Rhizopus after handling for marketing. There are numerous other decay-causing fungi including black rot (Ceratocystis) and Fusarium rot. Seed piece treatment and postharvest curing are the main control measures for these organisms. In warm wet production conditions, bacterial rots can also cause postharvest losses.


Curing. The periderm of sweetpotato roots is easily damaged during harvest and handling, and this leads to an unsightly appearance, high rates of water loss, and increased susceptibility to decay. The process of curing the damaged skin or "wound healing" can be achieved by holding roots at 25-32°C (77-90°F) under high relative humidity (>90 to 100%) for several days to 1 week. The conditions for curing sweetpotatoes are similar to those used for other tropical root and tuber crops. Growers often load bins of warm roots into storage rooms and do not turn on the fans for

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evaporative cooling until after about 1 week. This interval before cooling provides the warm humid conditions necessary for curing wounds.

Tomato

Maturity Indices

Standard Tomatoes: Minimum harvest maturity (Mature Green 2) is defined by internal fruit structure indices. Seeds are fully developed and are not cut upon slicing the fruit. Gel formation is advanced in at least one locule and jellylike material is forming in other locules.

ESL* Tomatoes: Off-vine ripening is severely affected if fruit are harvested at the MG2 stage. Minimum harvest maturity is better defined as equivalent to ripeness class Pink (USDA Color Stage 4 more than 30 percent but no more than 60 percent of the fruit surface, overall, shows a pink-red color.)

* Extended Shelf-Life trait is due, in part, to either the presence of the rin or nor gene.

Quality Indices

Standard tomato quality is primarily based on uniform shape and freedom from growth or handling defects. Size is not a factor of grade quality but may strongly influence commercial quality expectations.

Shape - well formed for type (round, globe, flattened globe, roma) Color - Uniform color (orange-red to deep red; light yellow). No green shoulders. Appearance - Smooth and small blossom-end scar and stem-end scar. Absence of growth cracks, catfacing, zippering, sunscald, insect injury, and mechanical injury or bruises. Firmness - Yields to firm hand pressure. Not soft and easily deformed due to an overripe condition. U.S. grades are No. 1, Combination, No. 2, and No. 3. Distinction among grades is based predominantly on external appearances, bruising and firmness.

Greenhouse grown tomatoes are graded as U.S. No. 1 or No. 2 only.

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Optimum Temperature

Mature Green 12.5 - 15°C (55 - 60°F) Light Red (USDAColor Stage 5) 10 - 12.5°C (50 - 55°F) Firm-ripe (USDA Color Stage 6) 7 - 10°C (44 - 50°F) for 3-5 days

Mature-green tomatoes can be stored up to 14 days prior to ripening at 12.5°C (55°F) without significant reduction of sensory quality and color development. Decay is likely to increase following storage beyond two weeks, at this temperature. Typically 8-10 days of shelflife are attainable within the optimum temperature range after reaching the Firm-ripe stage. Short term storage or transit temperatures below this range are used by some in the trade but will result in chilling injury after several days. Extended storage with controlled atmosphere has been demonstrated. (See Responses to CA)

Ripening Temperatures

18° -21°C (65 - 70°F); 90-95% R.H. for standard ripening 14° -16°C (57- 61°F) for slow ripening (i.e. in transit). For more details on ripening conditions see Ripening.

Chilling Injury

Tomatoes are chilling sensitive at temperatures below 10°C (50°F) if held for longer than 2 weeks or at 5°C (41°F) for longer than 6-8 days. Consequences of chilling injury are failure to ripen and develop full color and flavor, irregular (blotchy) color development, premature softening, surface pitting, browning of seeds, and increased decay (especially Black mold caused by Alternaria spp.). Chilling injury is cumulative and may be initiated in the field prior to harvest.


90-95%; High relative humidity is essential to maximize postharvest quality and prevent water loss (desiccation). Extended periods of higher humidity or condensation may encourage the growth of stem-scar and surface molds.

Rates of Respiration Temperature ml CO2/ kg·hr

Mature-green Ripening5°C (41°F) 3-4NR

10°C (50°F) 6-9 7-815°C (59°F) 8-14 12-15

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20°C (68°F) 14-20 12-2225°C (77°F) 18-26 15-26

To calculate heat production, multiply ml CO2 / kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton /day. NR - not recommended for more than a few days due to chilling injury


1.2 - 1.5µl / kg·hr at 10°C (50°F) 4.3 - 4.9µl / kg·hr at 20°C (68°F)


Tomatoes are sensitive to exogenous ethylene and exposure of mature-green fruit to ethylene will initiate ripening. Ripening tomatoes produce ethylene at a moderate rate and co-storage or shipment with sensitive commodities, such as lettuce and cucumbers, should be avoided.

Ripening

Faster ripening results from higher temperatures between 12.5 -25°C (55-77°F); 90-95% R.H.; 100 ppm ethylene. Good air circulation must be maintained to ensure temperature uniformity within the ripening room and to prevent the accumulation of CO2. CO2 (above 1%) retards the action of ethylene in stimulating ripening.

The optimum ripening temperature to ensure sensory and nutritive quality is 20°C (68°F). Color development is optimal and retention of vitamin C content is highest at this ripening temperature. Tomatoes allowed to ripen off-the-vine above 25°C (77°F) will develop a more yellow and less red color and will be softer.

Ethylene treatment typically extends for 24-72 hours. A second treatment period may follow repacking if immature green fruit were included in the harvest.


Controlled atmosphere storage or shipping offer a moderate level of benefit. Low O2

levels (3-5%) delay ripening and the development of surface and stem-scar molds without severely impacting sensory quality for most consumers. Storage times of up to 7 weeks have been reported for tomatoes using a combination of 4% O2, 2% CO2, and 5% CO. More typically, 3% O2 and 0-3% CO2 are used to maintain acceptable quality for up to 6 weeks prior to ripening. Elevated CO2 above 3-5 % is not tolerated by most cultivars and

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will cause injury. Low O2( 1%) will cause off-flavors, objectionable odors, and other condition defects, such as internal browning.


See Chilling injury.

Freezing Injury. Freezing injury will be initiated at -1°C (30°F), depending on the soluble solids content. Symptoms of freezing injury include a watersoaked appearance, excessive softening, desiccated appearance of the locular gel.

Physical Disorders

Tomatoes are sensitive to many production and environment-genetic interaction disorders which may Disorders be manifested during postharvest ripening or postharvest inspection. Fertilizer and irrigation management, weather conditions, insect feeding injury, asymptomatic virus infection, and unknown agents may interact to affect postharvest quality. Examples are Blossom-end Rot, Internal White Tissue, Rain Checking, Concentric and Radial Cracking, Puffiness, Persistent Green Shoulder, and Graywall. Several references with photographic keys to disorders are available.


Diseases are an important source of postharvest loss depending on season, region and handling practices. Commonly, decay or surface lesions result from the fungal pathogens Alternaria (Black Mold Rot), Botrytis (Gray Mold Rot), Geotrichum (Sour Rot), and Rhizopus (Hairy Rot). Bacterial Soft Rot caused by Erwinia spp. can be a serious problem particularly if proper harvest and packinghouse sanitation is not used. Treatment with hot air or hot water immersion (55°C for 0.5 - 1.0 min.) has been effective in preventing surface mold but has not been used extensively for commercial treatments. CA can be effective in delaying fungal growth on the stem-end and fruit surface.

Greenhouse tomatoes marketed on-the-vine ("cluster tomatoes") are very susceptible to Botrytis Gray Mold, especially if film-wrapped in a tray.


Rapid cooling soon after harvest is essential for optimal postharvest keeping quality. The precooling endpoint is typically 12.5°C (55°F). Forced-air cooling is the most effective practice but room cooling is more common.

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FRUITSAvocado

Maturity Indices

Percent of dry matter is highly correlated with oil content and is used as a maturity index in California and most other avocado production areas; minimum dry matter required ranges from 19 to 25%, depending on cultivar (19.0% for 'Fuerte', 20.8% for 'Hass', and 24.2% for 'Gwen').

Florida-grown avocado cultivars have lower oil content and are harvested on the basis of a calendar date (days after full bloom).

Quality Indices

Size (range of consumer preference); shape (cultivar-dependent); skin color; freedom from defects such as misshapen, sunburn, wounds and skin blemishes (rubs, insect damage, hail, and wind scars), rancidity and flesh browning; and freedom from disease, including anthracnose and stem-end rot.

Some cultivars are held on the tree for extended periods after achieving horticultural maturity. On-tree storage may result in development of off-flavors or rancidity with overmaturity. Off-flavors may also develop when fruit are harvested during periods of hot weather.

Avocado Abrasions

Optimum Temperature

5-13°C (41-55°F) for mature-green avocados, depending on cultivar and duration. 2-4°C (36-40°F) for ripe avocados.


90-95%


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Temperatura 5°C (41°F) 10°C (50°F) 20° (68°F)ml CO2/ kg·hr 10-25 25-80 40-150

To calculate heat production multiply ml CO2 /kg·hr by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.


Avocado fruits do not ripen on the tree and ethylene production begins after harvest and increases greatly with ripening to > 100µl C2H4/kg·hr at 20°C (68°F).


Treatment with 100ppm ethylene at 20°C (68°F) for 48 hours (early-season fruits), 24 hours (mid-season fruits), or 12 hours (late-season fruits) induces avocados to ripen in 3-6 days, depending on cultivar and maturity. Ripening indices include flesh softening and change of skin color from green to black in some cultivars such as 'Hass'. Ripe (soft) avocados require care in handling to minimize physical damage.

Responses to Controlled Atmospheres (CA) Optimum CA (2-5% O2 and 3-10% CO2) delay softening and skin color changes

and reduce respiration and ethylene production rates. CA reduces chilling injury of avocado. Mature-green 'Hass' avocado can be kept

at 5-7°C (41-45°F) in 2% O2 and 3-5% CO2 for 9 weeks, then ripened in air at 20°C (68°F) to good quality. Exclusion and/or removal of ethylene from CA storage are recommended.

>10% CO2 may increase skin and flesh discoloration and off-flavor development, especially when O2 is <1%.


Chilling injury. Skin pitting, scalding, and blackening are the main external chilling injury symptoms on mature-green avocado kept at 0-2°C (32-36°F) for more than 7 days before transfer to ripening temperatures. Avocados exposed to 3-5°C (37-41°F) for more than two weeks may exhibit internal flesh browning (grey pulp, pulp spot, vascular browning), failure to ripen, and increased susceptibility to pathogen attack. The timing of chilling injury development and its severity depend on cultivar, production area, and maturity-ripeness stage.

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Anthracnose. Caused by Colletotrichum gloeosporioides and appears as the fruit begins to soften as circular black spots covered with pinkish spore masses in later stages. Decay can penetrate through the flesh and induce browning and rancid flavor.

Stem-end rot. Caused by Botryodiplodia theobromae and appears as dark-brown to black discoloration which begins at the stem and advances toward the blossom end, finally covering the entire fruit. Dothiorella gregaria is another cause of stem-end rot in ripe avocados.

Control methods include good orchard sanitation, effective preharvest fungicide application, careful handling to minimize physical injuries, prompt cooling to optimum temperature for the cultivar and maintaining that temperature during marketing.

Insect Control Cold treatment (1°C for 14 days) can be tolerated without chilling injury if

avocados are conditioned for 12-18 hours at 38°C before the cold treatment. Avocados do not tolerate heat treatments and/or controlled atmospheres needed

for insect control.

Banana

Maturity Indices

Degree of fullness of the fingers, i.e., disappearance of angularity in a cross section. Bananas are harvested mature-green and ripened upon arrival at destination markets since fruits ripened on the plant often split and have poor texture.

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Quality Indices

Maturity (the more mature the better the quality when ripe); finger length (depending on intended use and demand for various sizes); freedom from defects, such as insect injury, physical damage, scars, and decay.

As bananas ripen their starch content is converted into sugars (increased sweetness). Other constituents that influence flavor include acids and volatiles.

Optimum Temperature

13-14°C (56-58°F) for storage and transport 15-20°C (59-68°F) for ripen


90-95%

Rates of Respiration Production

Temperature 13°C(56°F) 15°C(59°F) 18°C(65°F) 20°C(68°F) ml CO2/kg·hr1, 2 10-30 12-40 15-60 20-70

1Low end for mature-green bananas and high end for ripening bananas

2To calculate heat production multiply ml CO2/kg·h by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day.

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Rates of Ethylene Production Temperature 13°C(56°F) 15°C(59°F) 18°C(65°F) 20°C(68°F) ul C2H4/kg·hr1 0.1-2 0.2-5 0.2-8 0.3-10



Most commercial cultivars of bananas require exposure to 100-150 ppm ethylene 24-48 hours at 15-20°C (59-68°F) and 90-95% relative humidity to induce uniform ripening. Carbon dioxide concentration should be kept below 1% to avoid its effect on delaying ethylene action. Use of a forced-air system in ripening rooms assures more uniform cooling or warming of bananas as needed and more uniform ethylene concentration throughout the ripening.

Responses to Controlled Atmospheres (CA) 2-5% O2 and 2-5% CO2 CA delays ripening and reduces respiration and ethylene production rates. Postharvest life potential of mature-green bananas: 2-4 weeks in air and 4-6

weeks in CA at 14°C (58°F) Exposure to<1% O2 and/or >7% CO2 may cause undesirable texture and flavor. Use of CA during transport to delay ripening has facilitated picking bananas at the

full mature stage.


Chilling injury. Symptoms include surface discoloration, dull or smokey anal color, subepidermal tissues reveal dark-brown streaks, failure to ripen, and, in severe cases, flesh browning. Chilling injury results from exposing bananas to temperatures below 13°C (56°F) for a few hours to a few days, depending on cultivar, maturity, and temperature. For example, moderate chilling injury will result from exposing mature-green bananas to one hour at 10°C (50°F), 5 hours at 11.7°C (53°F), 24 hours at 12.2°C (54°F), or 72 hours at 12.8°C (55°F). Chilled fruits are more sensitive to mechanical injury.

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Skin abrasions. Abrasions result from skin scuffing against other fruits or surfaces of handling equipment or shipping boxes. When exposed to low (<90%) relative humidity conditions, water loss from scuffed areas is accelerated and their color turns brown to black.

Impact bruising. Dropping of bananas may induce browning of the flesh without damage to the skin.


Crown rot. This disease is caused by one or more of the following fungi: Thielaviopsis paradoxa, Lasiodiplodia theobromae, Colletotrichum musae, Deightoniella torulosa, and Fusarium roseum--which attack the cut surface of the hands. From the rotting hand tissue the fungi grow into the finger neck and with time, down into the fruit.

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Anthracnose. Caused by Colletrichum musae, becomes evident as the bananas ripen, especially in wounds and skin splits.

Stem-end rot. Caused by Lasiodiplodia theobromae and/or Thielaviopsis paradoxa, which enter through the cut stem or hand. The invaded flesh becomes soft and water-soaked.

Cigar-end rot. Caused by Verticillium theobromae and/or Trachysphaera fructigena. The rotted portion of the banana finger is dry and tends to adhere to fruits (appears similar to the ash of a cigar).

Control strategies. Minimizing bruising; prompt cooling to 14°C (58°F); proper sanitation of handling facilities; hot water treatments [such as 5 minutes in 50°C (120°F) water] and/or fungicide (such as Imazalil) treatment to control crown rot.

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Cantaloupe

Introduction

Cantaloupe (Cucumis melo L. var. reticulatus Naud.) is often, incorrectly, referred to interchangeably as Muskmelon. This botanical group, however, includes honeydew, crenshaw, Persian, casaba and other 'mixed melons.

Maturity Indices

Cantaloupes are harvested by maturity and not by size. Commercial maturity is ideally at the firm-ripe stage or "3/4 to full-slip" when a clear abscission (slip, separation) from the vine occurs with light pressure. Cantaloupes ripen after harvest but do not increase in sugar content (see below).

Cultivars vary in their external color at this stage of maturity and may retain a greenish cast. This skin color typically transitions from gray to dull green when immature, deep uniform green at maturity, and light yellow at full ripeness. A raised and well-rounded netting on the fruit surface is another indicator of proper commercial maturity.

Quality Indices

Well-shaped nearly spherical and uniform in appearance. Smooth stem end with no adhering peduncle (stem-attachment) which suggests premature harvest. Absence of scars, sunburn or surface defects. Firm with no evidence of bruising or excessive scuffing. Appears heavy for size and has firm internal cavity without loose seeds or liquid accumulation.

U.S. grades are Fancy, No. 1, Commercial and No. 2. Distinction among grades is based predominantly on external appearances and measured soluble solids. Federal Grade Standards specify a minimum of 11% soluble solids for U.S. Fancy ("Very good internal quality") and 9% soluble solids for U.S. 1 ("Good internal quality"). A calibrated refractometer, measuring °Brix, is accepted as the current standard for soluble solids measurements.

Sizing is based on count per 18.2 kg (40 lb.) container, most typically 9,12,15 and occasionally 18 or 23 melons per carton. An 18 to 45 count crate may also be used.

Optimum Temperature

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2.2° - 5°C ( 36°- 41°F) Storage life is up to 21 days at 2.2°C (36°F) but sensory quality may be reduced. Typically 12-15 days of shelf life are attainable within the optimum range. Short term storage or transit temperatures below this range are used by some in the trade but may result in chilling injury after several days [for example,7 days or longer at temperatures below 2.2°C (36°F)].


90%-95%; High relative humidity is essential to maximize postharvest quality and prevent desiccation. Water loss through scuffed and damaged surface netting can be significant. Extended periods of higher humidity or condensation may encourage the growth of stem-scar and surface molds.


Temperature0°C

(32°F)5°C

(41°F)10°C

(50°F)15°C

(59°F)20°C

(68°F)25°C

(77°F)ml CO2/kg·hr 2 - 3NR 4 - 5 7 - 8 17 - 20 23 - 33 65 - 71

To calculate heat production multiply ml CO2/kg·h by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.

NR - not recommended for more than a few days due to chilling injury.


Intact fruit - 40 - 80µl /kg·h at 20°C (68°F) Production Fresh-cut - 7-10µl /kg·h at 5°C (41°F)


Cantaloupes are moderately sensitive to exogenous ethylene and over-ripening may be a problem during distribution and short-term storage.


Controlled atmosphere storage or shipping offer only moderate benefits for cantaloupes under most conditions. With extended transit times (14-21 Atmospheres (CA) days), cantaloupes are reported to benefit from delayed ripening, reduced respiration and associated sugar loss, and inhibition of surface molds and decay. Consensus atmospheres of 3% O2 and 10% CO2 at 3°C (37.4°F) has been demonstrated. Elevated CO2 at 10-20% is tolerated but will cause effervescence in the fruit flesh. This carbonated flavor is lost on transfer to air.

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Low O2 (<1%) or high CO2 (> 20%) will cause impaired ripening, off-flavors and odors, and other condition defects.


Chilling injury typically occurs after storage at temperatures < 2°C Disorders ( 35.6°F) for several days. Sensitivity to chilling injury decreases as melon maturity and ripeness increases. Symptoms of chilling injury include pitting or sunken areas, failure to ripen, off-flavors and increased surface decay.


Disease can be an important source of postharvest loss depending on season, region and handling practices. Commonly, decay or surface lesions result from the fungal pathogens Alternaria, Penicillium, Cladosporium, Geotrichum, Rhizopus, and to a lesser extent Mucor. Treatment with hot air or hot water immersion ( 55°C for 0.5 - 1.0 min.) has been effective in preventing surface mold but has not been used extensively for commercial treatments. CA can be effective in delaying fungal growth on the stem-end and fruit surface.


Rapid precooling soon after harvest is essential for optimal postharvest keeping quality. The precooling endpoint is typically 10°C (50°F) but 4°C (39.2°F) is more desirable. Forced-air cooling is the most common practice but Hydrocooling is also utilized.

Durian

Maturity Indices

The fruit is a large (1.5 to 2.5 kg), spiny capsule that opens into five segments containing seeds covered with a pulpy, edible aril. External color changes with maturation from dull olive-green to light yellowish-green. When mature, the fruit drops to the ground, but it can be carefully harvested before this occurs and ripened in 4 to 6 days. Ease of fruit abscission can be used as a maturity index. Fruit is picked with peduncle attached.

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Quality Indices Fruit size (weight), shape, color, freedom from defects and decay. Internal quality: good color and flavor, fine texture, no wet core or browning. The overall smell of the ripe durian has three distinct aromas: one strong and

onion like, one delicate and fruity, and one offensive smell (due to hydrogen sulfide and diethyldisulfide).

Optimum Temperature

13-15°C (55-59°F); storage potential is 3-5 weeks (mature unripe durians) or 7-14 days (ripe durians).


90-95%


Vary by cultivar and ripeness stage from 6 to 60 ml CO2/kg·hr at 13ºC (55ºF) and from 100 to 250 ml CO2/kg·hr at 25ºC (77ºF); climacteric respiratory pattern.



Vary from 1 to 7 µl/kg·hr at 13ºC (55ºF) and from 6 to 35 µl/kg·hr at 25ºC (77ºF), depending on cultivar and ripeness stage.


Ethylene (100ppm) treatment can accelerate ripening and dehiscence of mature but unripe durians and ethylene scrubbing can delay their ripening.


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An atmosphere of 3-5% O2 and 5-15% CO2 reduces respiration and ethylene production rates, retards ripening, and extends postharvest-life of durians to 8 weeks (vs. 5 weeks in air) at 14ºC (58ºF).


Chilling Injury. Symptoms include black discoloration of durian surface (especially the groove between thorns) and failure to ripen as indicated by loss of ability to convert starch to sugars. Cultivars vary in their chilling sensitivity but all are damaged by storage at 5ºC (41ºF) for one week or 10ºC (50ºF) for two weeks.

Uneven Fruit Ripening. A portion of the aril remains hard, leathery, whitish in color, odorless, and tasteless. Larger fruits may have a higher incidence of this disorder than smaller fruits. Incidence and severity are related to preharvest factors that have not been identified yet.

Wet Core (Water Core). Flesh areas appear water-soaked and deteriorate faster than unaffected areas. It is caused by rain just before harvesting.


Fruit rot may be caused by Phytophthora palmivora. Symptoms first appear as small water-soaked lesions on the outer skin which coalesce to form dark-brown lesions followed by the appearance of white powdery masses of sporangia. Control strategies include application of fungicides about one month before harvest, minimizing physical injuries during harvesting and handling, and using good sanitation and temperature management procedures.

Grape

Maturity Indices

In California, harvest date is determined by Soluble Solids Concentration (SSC) of 14 to 17.5% depending on cultivar and production area. In some situations, the SSC/titratable acidity (TA) ratio of 20 or higher is used to determine maturity for early maturing cultivars from early production areas. For red and black colored cultivars, there is also a minimum color requirement.

Quality Indices

High consumer acceptance is attained for fruit with high SSC or SSC/TA ratio. Berry firmness is also an important factor for consumer acceptance as are lack of defects such as decay, cracked berries, stem browning, shriveling, sunburned or dried berries, and insect damage.

Optimum Temperature

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Berry storage at -1.0 to 0° C (30-32° F) is recommended.

The highest freezing point for berries is -2.1° C (28.1° F), but freezing point varies depending on SSC. A -2.0° C (28° F) stem freezing point has been reported.


90-95% RH and an air velocity of approximately 20-40 feet per minute (FPM) is suggested during storage.

Rates of Respiration (of grape clusters, i.e. berries + stems)

Temperature ml CO2 /kg·hr* 0° C (32° F) 1-2 5° C (41° F) 3-4

10° C (50° F) 5-8 20° C (68° F) 12-15

Stem respiration rate is approximately 15 times higher than berry respiration.* To calculate heat production, multiply ml CO2 /kg·hr by 440 to get BTU/ton/day or by 122 to get kcal/metric ton/day.


<0.1 m l/kg·hr at 20° C (68° F)


Table grapes are not very sensitive to ethylene. However, exposure to ethylene (>10 ppm) may be a secondary factor in shatter.


CA (2-5% O2 + 1-5% CO2 ) during storage/shipment is not currently recommended for table grapes because its benefit is slight and SO2 used for decay control.

Effects of Genotype on Market Life

Market life varies among table grape cultivars grown in California and is also strongly affected by temperature management and decay susceptibility.


Shatter. (loss of berries from the cap stem) In general, shatter increases in severity with increasing maturity, i.e., the longer the fruit remains on the vine. Berries of seedless

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cultivars, are usually less well attached to the cap stem than seeded cultivars. Shatter varies considerably from season to season, and there is a large difference among varieties. Gibberellin applied at fruit set weakens berry attachment. Shatter occurs mainly due to rough handling during field packing with additional shatter occurring all the way to the final retail sale. Shatter incidence can be reduced by controlling pack depth and fruit packing density (cubic inches per pound), using cluster bagging, gentle handling and maintaining recommended temperature and relative humidity

Waterberry. Waterberry is associated with fruit ripening and most often begins to develop shortly after veraison (berry softening). The earliest symptom is the development of small (1-2 mm) dark spots on the cap stems (pedicles) and/or other parts of the cluster framework. These spots become necrotic, slightly sunken, and expand to affect more areas. The affected berries become watery, soft, and flabby when ripe. In California, this disorder has been associated with a high nitrogen status vine, canopy shading, or cool weather during veraison and fruit ripening. Avoid over fertilization with nitrogen. Foliar nutrient sprays of nitrogen should be avoided in waterberry-prone vineyards. Trimming off affected berries during harvest and packing is a common practice, although labor intensive.


Gray Mold. (Botrytis cinerea) Gray mold is the most destructive of the postharvest diseases of table grapes, primarily because it develops at temperatures as low as 31° F (-0.5° C) and grows from berry to berry. Gray mold first turns berries brown, then loosens the skin of the berry, its white, thread-like hyphal filaments erupt through the berry surface, and finally masses of gray colored spores develop. Wounds near harvest also provide opportunities for infections. No wound is required for infection when wet conditions occur.

Botrytis infection can be reduced by removing desiccated, infected grapes of the previous season from vines, leaf-removal canopy management, preharvest fungicides, trimming visibly infected, split, cracked, or otherwise damaged grapes before packing, prompt cooling and fumigation with sulfur dioxide (100 ppm for one hour) or use of continuous release SO2 pads.

Grapefruit

Maturity Indices

Color (more than 2/3 of fruit surface showing yellow color) and a minimum soluble solids/acid ratio of 5.5 or 6 (depending on production area). Grapefruit do not continue to ripen after harvest so they should be harvested fully-ripe (with good flavor).

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Quality Indices

Color intensity and uniformity; firmness; size; shape; peel thickness; smoothness; and freedom from decay and defects, such as freezing injury, rind staining, pitting, scars, and insect damage. Flavor is related to soluble solids/acid ratio and concentration of compounds that impart bitter flavor (limonin and naringin).

Optimum Temperature

12-14°C (54-57°F) depending on cultivar, production area, maturity-ripeness stage at harvest, and storage & transport duration (up to 6-8 weeks).


90-95%

Rates of Respiration Temperature 10°C (50°F) 13°C (55°F) 15° (59°F) 20° (68°F)ml CO2/ kg·hr 3-5 4-7 5-9 7-12



Less than 0.1 µl/kg·hr at 20°C (68°F)


Exposure of mature-green grapefruits for 1-3 days to ethylene (1-10ppm) at 20-30°C (68 to 86°F) accelerates loss of green color and appearance of yellow color (degreening). This is accompanied by faster peel senescence and greater susceptibility to decay-causing pathogens.

Responses to Controlled Atmospheres (CA) Low O2 (3-10%) and high CO2 (5-10%) concentrations delay senesence and

maintain firmness of grapefruits kept at 13-15°C (55-59°C). Exposure to O2 levels below 3% and/or CO2 levels above 10% may result in off-

flavors due to accumulation of acetaldehyde, ethanol, and ethyl acetate. This precludes the use of fungistatic levels of CO2 (>10%) for longer than a few days.

Commercial use of CA during transport and/or storage of grapefruits is very limited.


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Chilling injury. Severity of chilling injury depends upon cultivar, maturity and ripeness stage at harvest, production area and season (preharvest cultural practices and weather conditions). Symptoms including pitting, reddish brown discoloration, scald, watery breakdown, off-flavors, and increased decay incidence. Waxing or film wrapping to minimize water loss and use of fungicides (especially thiabendazole) to control decay can reduce severity of chilling injury symptoms. Conditioning at 15-18°C (59-65°F) in air or in air + 10-20% CO2 for 5-7 days can reduce severity of chilling injury symptoms on grapefruits that are subsequently exposed to chilling temperatures, such as those required for quarantine treatments against tropical fruit flies.

Oil spotting (Oleocellosis). Physical stress on turgid fruits may result in breaking of oil cells and release of oil that damages surrounding tissues.

Pathological Disorders Important Diseases:

Green mold (Penicillium digitatum) Blue mold (Penicillium italicum) Phomopsis stem-end rot (Phomopsis citri) Stem end rot (Lasiodiplodia theobromae) Brown rot (Phytophthora citrophthora) Sour rot (Geotrichum candidum)

Control Strategies:

Careful handling to minimize physical damage. Good sanitation in the orchards and packing houses. Treatment with hot water dip (50-53°C = 120-125°F for 2-3 minutes) or drench

(55°C = 129°F for 20-30 seconds). Treatment with postharvest fungicides and/or biological antagonists. Prompt cooling and expedited handling. Removal and/or exclusion of ethylene.

Guava

Maturity Indices

Guava fruits are picked at the mature-green stage (color change from dark- to light-green) in some countries where consumers eat them at that stage. In countries where consumers prefer ripe guava, the fruits are picked at the firm-yellow to half-ripe (softer) stage for long-distance transport or at the fully-ripe (yellow and soft) stage for local markets.

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Quality Indices

Color is a good indicator of ripeness stage; size and shape may be important in some markets; freedom from defects, insects, and decay; firmness and extent of gritty texture due to the presence of stone cells (sclereids); flesh color depends on cultivar and can be white, yellow, pink, or red; amount of seeds in the flesh (the fewer the better); aroma intensity; soluble solids and acidity.

Guava is one of the richest sources of vitamin C (200 to 400 mg per 100g fresh weight) and some cultivars are also rich in vitamin A.

Optimum Temperature

8-10°C (46-50°F) for mature-green and partially-ripe guavas (storage potential = 2-3 weeks)

5-8°C (41-46°F) for fully-ripe guavas (storage potential = 1 week)


90-95%


Temperature ml CO2 / kg·hr 10°C (50°F) 4-3020°C (68°) 10-70

To calculate heat production multiply ml CO2 /kg·hr by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.


Guava is a climacteric fruit. Rates of respiration and ethylene production depend upon cultivar and maturity/ripeness stage. Ethylene production at 20°C (68°F) ranges from 1 to 20 µl /kg•hr.


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Ethylene at 100 ppm for 1-2 days can accelerate ripening of mature-green guavas to full-yellow stage at 15-20°C (59-68°F) and 90-95% relative humidity. This treatment results in more uniform ripening, which is more important for guavas destined for processing. Immature-green guavas do not ripen properly and develop 'gummy' texture.


The limited research on guava indicates that 2-5% oxygen levels may delay ripening of mature-green and partially-ripe guavas kept at 10°C (50°F). Tolerance to elevated carbon dioxide levels has not been determined.

Physical and Physiological Disorders

Chilling injury. Symptoms include failure of mature-green or partially-ripe guavas to ripen, browning of the flesh and, in severe cases, the skin, and increased decay incidence and severity upon transfer to higher temperatures. Fully-ripe guavas are less sensitive to chilling injury than mature-green guavas and may be kept for up to a week at 5°C (41°F) without exhibiting chilling injury symptoms.

External (skin) and Internal (flesh) browning. Guavas are sensitive to physical damage during harvesting and handling all the way to the consumer. Symptoms include skin abrasions and browning of bruised areas.

Sun scald. Guavas exposed to direct sun light may be scalded. In some countries, paper bags are used to cover guava fruits and protect them from solar radiation and insect infestation while on the tree.


Most of the postharvest disease problems begin in the orchard as latent infection in developing fruits. Diseases include anthracnose (caused by Colletrotrichum gloeosporioides and associated species), aspergillus rot (caused by Aspergillus niger), mucor rot (caused by Mucor hiemalis), phomopsis rot (caused by Phomopsis destructum), and rhizopus rot (caused by Rhizopus stolonifer).

Disease control strategies include good orchard sanitation, effective preharvest management to reduce infection, careful handling to reduce physical damage, prompt cooling to 10°C (50°F) and subsequent maintenance of that temperature throughout the handling system.

Insect Control

Guavas are a preferred host for fruit flies and must be treated for disinfestation to be accepted in many countries. One of the insect control treatments is heat either as

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immersion in 46°C-water for 35 minutes or exposed to hot air at 48°C for 60 minutes. Another potential insect control treatment is irradiation at 0.15-0.30 kGy.

Honeydew Melon

Introduction

Honeydew melon belongs to the Cucumis melo L. Inodorus group which includes crenshaw, casaba and other mixed melons.

Maturity Indices

Honeydews are harvested by maturity and not by size. Maturity is difficult to judge because no clear abscission (slip, separation) from the vine occurs. Maturity classes are grouped predominantly by changes in ‘ground color' from greenish to cream with yellow accents.

Commercial Maturity Classes:

1. Mature, Unripe. Ground color white with greenish accents, no characteristic aroma, peel fuzzy/hairy and not waxy. California Grade Standards establish a minimum legal harvest index of 10% soluble solids (10° Brix).

2. Mature, Ripening. Ground color white with slightly discernible green tint, slightly waxy peel, blossom-end firm and unyielding, no or slight aroma. Preferred commercial maturity class.

3. Ripe. Ground color creamy white with yellow accents, clearly waxy peel, characteristic aroma noticeable, blossom-end yields slightly to press

Quality Indices

Well-shaped nearly spherical and uniform in appearance. Absence of scars or surface defects, no evidence of bruising, appears heavy for size, surface waxy and not fuzzy.

U.S. grades are No. 1, Commercial and No. 2. Distinction among grades is based predominantly on external appearances. Sizing is based on count per 13.6 kg (30 lb.) container, most typically 4 or 5, and occasionally 6 melons per carton. High quality

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appearance is protected, in part, by packing with a partition to protect melons from bruising, compression and scuffing.

Optimum Temperature

7° - 10°C ( 45°- 50°F ) Storage life is typically 12-15 days at 7°C(45°F) with up to 21 days attainable.

Source authorities vary in the reported optimum storage and shipping temperatures for honeydew melons. Most recommendations use 7°C (45°F) and 85-90% R.H. as the optimum handling conditions. In general, if melons are ripe or pretreated with ethylene at 100 ppm for 24 hr, trade recommendations for short-term storage and shipping are often range from 2.5 - 5°C (36.5 - 41°F). Extended holding at these temperatures will induce chilling injury, rapidly evident after transfer to typical retail display temperature


85-90 %. High relative humidity is essential to prevent desiccation and loss of glossiness. Extended periods of higher humidity or condensation may encourage the growth of surface molds.


Temperature0°C

(32°F)5°C

(41°F)10°C

(50°F)15°C

(59°F)20°C

(68°F)25°C

(77°F)ml CO2/kg·h NR 3 - 5 7 - 9 12 - 16 20 - 27 20 - 35

To calculate heat production multiply ml CO2/kg·hr by 440 to get Btu/ton/ day or by 122 to get kcal/metric ton/day.

NR- not recommended due to chilling injury.


Maturity Class µl / kg·hr at 20°C (68°F) Intact fruit 1 .5-1.0 2 1.0-7.5 3 7.5-10 Fresh-cut 2 14-17 at 5°C(41°F) 3 21-25 at 5°C(41°F)


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Exposure to 100-150 ppm ethylene for 18-24 hr @ 20°C (68°F) has been used to ripen physiologically mature honeydew melons. Immature fruit will not soften and develop characteristic sensory quality even with C2H4 treatment. Ripening with C2H4 is no longer a common practice for the California honeydew industry.


Controlled atmosphere storage or shipping offer only moderate benefits for honeydew melons under most conditions. With extended transit times ( 1-28 days), naturally ripening melons are reported to benefit from delayed ripening, reduced respiration and inhibition of molds and decay. Consensus conditions of 3% O2 and 10% CO2 at 7°C have been demonstrated. Elevated CO2 at 10-20 % is tolerated but will cause effervescence in the fruit flesh. This carbonated flavor is lost on transfer to air.

Low O2 (<1%) or high CO2 (> 20%) will cause impaired ripening, off-flavors and odors, and other defects.


Chilling injury typically occurs after storage at temperatures < 7°C ( 45°F) for several days. Sensitivity to chilling injury decreases as melon maturity and ripeness increases. Symptoms of chilling injury include pitting, reddish-tan discoloration's, failure to ripen, off-flavors and increased surface decay.


Disease is generally not an important source of postharvest loss in comparison with physical injury due to bruising and chilling injury. Commonly, decay or surface molds are caused by the fungal pathogens Cladosporium, Geotrichum, Rhizopus, Alternaria, and occasionally Mucor and Fusarium.


Rapid forced-air cooling soon after harvest is strongly recommended, particularly if harvest pulp temperatures exceed 27°C (80°F). The precooling endpoint will depend on the desired intransit ripening, transit time, and trailer refrigeration capacities.

Fresh-cut honeydew melons rapidly absorb odors.

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The optimum temperature and handling conditions for honeydew melons are essentially applicable to crenshaw and Persian melons. The anticipated keeping period, however, is shorter and generally does not exceed 14 days. Casaba, Juan Canary, and Santa Claus melons retain best quality at the high end of the storage temperature range, 10°C (50°F), for up to 21 days.

Kiwifruit

Maturity Indices Minimum of 6.5% soluble solids content (SSC) at harvest. Minimum flesh firmness of 14 lbf (penetration force with an 8-mm = 5/16 inch

tip). Late harvested kiwifruits retain their firmness better than early harvested fruit and have higher SSC at harvest and when ripe.

Quality Indices Freedom from growth cracks, insect injury, bruises, scars, sunscald, internal

breakdown, and decay. Minimum of 14% SSC when ripe (ready to eat); a kiwifruit at 2-3 lb flesh

firmness is considered ripe. Kiwifruits are a good source of vitamin C.

Optimum Temperature

0°C (32°F); highest freezing point is -1.5°C (29.3°F).


90-95%


Temperature 0°C (32°F) 5°C(41°F) 10°C (50°F) 15°C (59°F) 20°C(68°F)Rates of Respiration

ml CO2/kg·hr1.5-2.0 3-4 5-7 9-12 15-20



Less than 0.1 µl/kg·hr at 0°C (32°F), 0.1-0.5 µl/kg·hr at 20°C (68°F) for Production unripe kiwifruit. Ripe kiwifruit (less than 4 lbf firmness) produce 50-100 µl/kg·hr at 20°C (68°F).


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Kiwifruits are extremely sensitive to ethylene. As little as 5-10 ppb ethylene will induce fruit softening.

Avoid exposure of unripe kiwifruits to ethylene during harvest, transport, and storage.


Optimum CA 1-2% O2 + 3-5% CO2. CA delays ripening and retains flesh firmness. CO2 levels above 7% can cause internal breakdown of the flesh. CA must be established within 2 days after harvest to maximize benefits; ethylene concentration should be kept below 20 ppb to avoid accelerated flesh softening and incidence of white core inclusions.


Freezing Damage. Flesh translucency starting at the stem end of the fruit and progressing toward the blossom end as the severity increases. Susceptible fruit become somewhat yellow fleshed with prolonged storage. There was no "graininess" observed in the fruit that showed these symptoms. Freezing damage can occur on early picked kiwifruit when stored at temperatures below 0°C (32°F) or when subjected to an early frost in the vineyard. Fruit frosted late in the season are usually affected on the shoulder where the cells collapse to cause a pinching of the fruit at the stem end.

Hard-Core.This disorder is induced by exposure of kiwifruit to ethylene plus carbon dioxide levels above 8 percent. The fruit core fails to ripen when the remainder of the fruit is soft and ripe.

Internal Breakdown. These symptoms start as a slight discoloration (water soaking) at the blossom end of the fruit. With time this progresses around the blossom end and ultimately encompasses a large part of the fruit. As symptoms progress a "graininess" develops below the fruit surface beginning in the area around the blossom end of the fruit.

Pericarp Granulation. The occurrence of granulation is predominantly at the stylar end of the fruit, but as in the case of translucency may extend up the sides of fruit. This disorder also is more severe with prolonged storage and after ripening at 20°C (68°F). There is no obvious correlation between pericarp translucency and granulation since symptoms can occur independently.

Pericarp Translucency. This disorder has been noted in both air- and CA-stored kiwifruit at 0°C (32°F). It appears as translucent patches in the outer pericarp tissue at the stylar end which may extend up the sides of the fruit. Pericarp translucency is more severe after prolonged storage, but it can be observed after 12 weeks of storage at 0 C (32 F). The presence of ethylene in the storage atmosphere exacerbates symptom development.

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White-Core Inclusions. The occurrence of white-core inclusions is directly related to the presence of ethylene in CA storage. This disorder results in distinct white patches of core tissue that are obvious in ripe fruit. Symptoms have been observed as early as 3 weeks after storage at 0°C (32°F).

Pathological Breakdown

Several pathogens can cause postharvest deterioration of kiwifruit. Botrytis gray mold rot caused by Botrytis cinerea is the most important and can directly invade the fruit or enter through wounds. Kiwifruit become much more susceptible to Botrytis (and other fungi) as they soften. Thus, maintaining fruit firmness (by rapid cooling, cold storage, and use of controlled atmospheres) can significantly reduce pathological breakdown. Sunburned fruit and physically damaged fruit are also more susceptible to postharvest diseases.

Lemon

Maturity Indices

A minimum juice content by volume of 28 or 30% depending on grade; color lemons picked at the dark-green stage have the longest postharvest life while those picked fully-yellow must be marketed more rapidly.

Quality Indices

Yellow color intensity and uniformity; size; shape; smoothness; firmness; freedom from decay; and freedom from defects including freezing damage, drying, mechanical damage, rind stains, red blotch, shriveling, and discoloration.

Optimum Temperature

12-14°C (54-57°F) depending on cultivar, maturity-ripeness stage at harvest, production area, and duration of storage and transport (can be up to 6 months).


90-95%


Temperature 10°C (50°F) 15° (59°F) 20° (68°F)ml CO2/ kg·hr 5-6 7-12 10-14


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< 0.1 µl/kg·hr at 20°C (68°F)


If degreeing is desired, lemons can be treated with 1-10 ppm ethylene for 1-3 days at 20 to 25°C (68-77°F), but this exposure may accelerate deterioration rate and decay incidence


CA of 5-10% O2 and 0-10% CO2 can delay senescence including loss of green color of lemons. Fungistatic CO2 levels (10-15% are not used because they may induce off-flavors due to accumulation of fermentative volatiles, especially if O2 levels are below 5%. Removal of ethylene from lemon storage facilities can reduce rate of senescence and decay incidence.


Chilling injury. Symptoms include pitting, membranous staining, and red blotch. Severity depends upon cultivar, production area, harvest time, maturity-ripeness stage at harvest, and time-temperature of postharvest handling operations. Moderate to severe chilling injury is usually followed by decay.

Oil spotting (Oleocellosis). Breaking of oil cells due to physical stress on turgid fruits causes release of the oil that damages surrounding tissues. Avoiding harvesting lemons when they are very turgid and careful handling reduce severity of this disorder.


Green mold. Caused by Penicillium digitatum which penetrates the fruit rind through wounds. Symptoms begin as water-soaked area at the fruit surface followed by growth of colorless mycelium, then sporulation (green color).

Blue Mold. Caused by Penicillium italicum which can penetrate the uninjured peel and can spread from one lemon to adjacent lemons. Symptoms are similar to green mold except that the spores are blue.

Altenaria rot. Caused by Alternaria citri which enters the lemons through their buttons. Preharvest treatment with gibberellic acid or postharvest treatment with 2,4D delay senescence of the buttons and subsequent decay by Alternaria.

Control Strategies:

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Careful handing during harvesting and handling to minimize cuts, scratches, and bruises.

Treatment with postharvest fungicides and/or biological agents. Prompt cooling to the proper temperature range. Maintaining optimum ranges of temperature and relative humidity and exclusion

of ethylene during transport and storage. Effective sanitation throughout the handling system.

Lime

Maturity Indices

Juice content by volume of 30% or higher and color (mature-green limes have a much longer postharvest-life than those picked when yellow; the latter must be marketed soon after harvest).

Quality Indices

Color (most consumers in the USA prefer green limes but in some other countries consumers prefer yellow limes because of their greater juice content); size; shape; firmness; smoothness; freedom from decay; and freedom from defects including bruises, oil spotting, dryness, freezing injury, and stylar-end breakdown.

Optimum Temperature

10-13°C (50-55°F) depending on cultivar, maturity-ripeness stage at harvest, and duration of storage + transport (up to 6-8 weeks).


90-95%

Rates of Respiration emperature 10°C (50°F) 15° (59°F) 20° (68°F)ml CO2/ kg·hr 3-5 5-8 6-10


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< 0.1 µl/kg·hr at 20°C (68°F)


Ethylene causes limes to lose their green color and unmask their yellow pigments, which is undesirable for marketing green limes. Removal of ethylene from lime storage facilities can be beneficial in retarding loss of green color and delaying decay incidence.


A combination of 5-10% O2 and 0-10% CO2 retards senescence (loss of green color) of limes, but is inadequate for decay control. Exposure to > 10% CO2 and/ or < 5% O2 can result in scald-like injury, decreased juice content, off-flavors, and increased susceptibility to decay. Commercial use of CA on limes is very limited.


Chilling injury. Symptoms include pitting, and brown discoloration. Pits Disorders may coalesce and form leathery, brown, sunken areas on the rind. Severity increases with lower temperature below 10°C (50°F) and longer durations of exposure to these temperatures.

Oil spotting (Oleocellosis). Harvesting and handling turgid limes may result in breakage of oil cells in the flavedo and release of the oil that damages surrounding tissues.

Stylar-end Breakdown. This disorder results from rough handling during harvesting and handling. Its severity varies among cultivars and harvest seasons.


Important Diseases:

Green mold (Penicillium digitatum)

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Blue mold (Penicillium italicum)

Stem-end rot (Lasiodiplodia theobromae) Phomopsis stem-end rot (Phomopsis citri) Alternaria stem-end rot (Alternaria citri)

Control Strategies:

Minimizing abrasions, cuts, and bruises during handling. Treating limes before harvest with gibberellic acid to delay senescence. Dipping in hot water (50-53°C = 120-125°F) for 2-3 minutes. Using chlorine in wash water, postharvest fungicides, and or biological

antagonists. Cooling to optimum temperature and subsequent maintenance of optimum

temperature and relative humidity. Avoiding exposure to ethylene.

Mango

Maturity Indices

Change in fruit shape (fullness of the cheeks). Change in skin color from dark-green to light-green to yellow (in some cultivars).

Red color on the skin of some cultivars is not a dependable maturity index Change in flesh color from greenish-yellow to yellow to orange.

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Quality Indices Uniformity of shape and size; skin color (depending on cultivar); flesh firmness. Freedom from decay and defects, including sunburn, sapburn, skin abrasions,

stem-end cavity, hot water scald, chilling injury, and insect damage. Changes associated with ripening include starch to sugar conversion (increased

sweetness), decreased acidity and increased carotenoids and aroma volatiles. There are large differences in flavor quality (sweetness, sourness, aroma) and

textural quality (fiber content) among cultivars.

Optimum Temperature

13°C (55°F) for mature-green mangoes 10°C (50°F) for partially-ripe and ripe mangoes


90-95%


Temperature 10°C(50°F) 13°C(55°F) 15°C(59°F) 20°C(68°F)ml CO2/kg·hr 12-16 15-22 19-28 35-80



Temperature 10°C(50°F) 13°C(55°F) 15°C(59°F) 20°C(68°F)ul C2H4/kg·hr 0.1-0.5 0.2-1.0 0.3-4.0 0.5-8.0

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Exposure to 100 ppm ethylene for 12 to 24 hours at 20 to 22°C (68 to 72°F) Ethylene and 90-95% relative humidity results in accelerated and more uniform ripening of mangoes within 5-9 days, depending on cultivar and maturity stage. Carbon dioxide concentration should be kept below 1% in the ripening room.

Responses to Controlled Atmospheres (CA) Optimum CA 3-5% O2 and 5-8% CO2 CA delays ripening and reduces respiration and ethylene production rates.

Postharvest life potential at 13°C (55°F): 2-4 weeks in air and 3-6 weeks in CA, depending on cultivar and maturity stage.

Exposure to below 2% O2 and/or above 8% CO2 may induce skin discoloration, grayish flesh color, and off-flavor development.


Sapburn. Dark-brown to black discoloration of mango skin due to chemical & Physiological injury from exudate (sap) from cut stem.

Skin abrasions. Abrasions due to fruit rubbing against rough surfaces or each other result in skin discoloration and accelerated water loss.

Chilling injury. Symptoms include uneven ripening, poor color and flavor, surface pitting, grayish scald-like skin discoloration, increased susceptibility to decay, and, in severe cases, flesh browning. Chilling injury incidence and severity depend on cultivar, ripeness stage (riper mangoes are less susceptible) and temperature and duration of exposure.

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Heat injury. Exposure to temperatures above 30°C (86°F) for longer than 10 days results in uneven ripening, mottled skin and strong flavor. Exceeding the time and/or temperature combinations recommended for decay and/or insect control, such as 46.4°C (115.5°F) water dip for 65-90 minutes (depending on fruit size) causes heat injury (skin scald, blotchy coloration, uneven ripening).

Internal flesh breakdown (stem-end cavity). Flesh breakdown and development of internal cavities between seed and peduncle. This disorder is more prevalent in tree-ripened mangoes.

Jelly-seed (premature ripening). Disintegration of flesh around seed into a jelly-like mass.

Soft-nose. Softening of tissue at apex. Flesh appears over-ripe and may discolor and become spongy. This disorder may be related to calcium deficiency.

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Anthracnose. Caused by Colletotrichum gloesporioides, begins as latent Disorders infections in unripe fruit and develops when the mangoes begin to ripen. Lesions may remain limited to the skin or may invade and darken the flesh.

Diplodia stem-end rot. Caused by Lasiodiplodia theobromae, affects mechanically-injured areas on the stem or skin. The fungus grows from the pedicel into a circular black lesion around the pedicel.

Control strategies:

1. Careful handling to minimize mechanical injuries. 2. Hot water treatment: 5-10 minutes (depending on fruit size) dip in 50°C ± 2°C

(122°F ± 4°F) water. 3. Postharvest fungicide (imazalil or thiabendazole) treatment alone or in

combination with hot water treatment maintaining optimum temperature and relative humidity during all handling steps.

Mangosteen

Maturity Indices

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Skin color change to reddish-purple is the primary maturity index for mangosteen. The fruit has a persistent calyx at the stem end and is picked with the peduncle attached. The aril (pulp) separates from the rind in ripe fruit.

Quality Indices

Fruit size, shape, color, and freedom from defects (skin cracks and blemishes, latex staining, insect damage)

The inedible pericarp is hard and the edible pulp is white, soft, juicy, and consists of 5 to 8 segments (similar to citrus fruits).

Soluble solids content ranges from 17 to 20% and titratable acidity ranges from 0.7 to 0.8% (pH = 4.5 to 5.0).

Optimum Temperature

13 ± 1°C (56 ± 2 °F), storage potential = 2-4 weeks, depending on cultivar and ripeness stage.


90-95%


6-10 ml CO2/ kg·hr at 20°C (68°F); climacteric respiratory pattern.



3-30 µl C2H4/ kg·hr at 20°C (68°F)


Exposure to 100 ppm ethylene for 24 hours at 20°C (68°F) accelerates ripening (color change to dark purple and softening of the pulp).

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Limited published information indicates a useful CA of 5% O2 + 5 to 10% CO2 for up to 4 weeks.


Chilling Injury. Symptoms include darkening and hardening of the skin and increased susceptibility to decay when the fruit is moved to higher temperatures following storage at less than 10°C (50°F) for longer than 15 days or at 5°C (41°F) for more than 5 days.

Translucent Flesh. Symptoms are internal and include flesh changes from white to translucent and textural changes from soft to firm and crisp. This disorder may result from mechanical injuries, nutrient imbalance, and/or excessive water uptake into the flesh.

Rind Hardening. Mechanical damage (compression or impact bruising) to the fruit during harvesting and handling often results in hardening of the rind, which may be combined with hardening and translucency of the pulp (one or more segments).


Decay may be caused by Botryodiplodia theobromae, Diplodia spp., Pestalotia flagisettula, Phomopsis spp., or Rhizopus spp

PapayaMaturity Indices

Change of skin color from dark-green to light-green with some yellow at the blossom end (color break). Papayas are usually harvested at color break to ¼ yellow for export or at ½ to ¾ yellow for local markets.

Flesh color changes from green to yellow or red (depending on cultivar) as the papayas ripen. A minimum soluble solids of 11.5% is required by the Hawaiian grade standards.

Quality Indices

Papayas picked ¼ to full yellow taste better than those picked mature- green to ¼ yellow because they do not increase in sweetness after harvest.

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Uniformity of size and color; firmness; freedom from defects such as sunburn, skin abrasions, pitting, insect injury, and blotchy coloration; freedom from decay.

Optimum Temperature

13°C (55°F) for mature-green to ¼ yellow papayas 10°C (50°F) for partially-ripe (¼ to ½ yellow) papayas 7°C (45°F) for ripe (>½ yellow) papayas


90-95%

Rates of Respiration Temperature 7°C (45°F) 10°C (50°F) 13°C (55°F) 15°C (59°F) 20°C (68°F)ml CO2/kg·hr 3 - 5 4 - 6 7 - 9 10 - 12 15 - 35


Rates of Ethylene Production Temperature 7°C (45°F) 10°C (50°F) 13°C (55°F) 15°C (59°F) 20°C (68°F)µl C2H4/kg·hr 0.1-2 0.2-4 0.3-6 0.5-8 1-15

Responses to Ethylene Production

Exposure to 100 ppm ethylene at 20 to 25°C (68 to 77°F) and 90-95% relative humidity for 24-48 hours results in faster and more uniform ripening (skin yellowing and flesh softening, but little or no improvement in flavor) of papayas picked at color break to ¼ yellow stage.


Optimum CA 3-5% O2 and 5-8% CO2

Benefits of CA include delayed ripening and firmness retention.

Postharvest life potential at 13°C (55°F): 2-4 weeks in air and 3-5 weeks in CA, depending on cultivar and ripeness stage at harvest.

Exposure to O2> levels below 2% and/or CO2 levels above 8% should be avoided because of the potential for development of off-flavors and uneven ripening.

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Skin abrasions result in blotchy coloration such as green islands (areas of skin that remain green and sunken when the fruit is fully-ripe) and accelerate water loss. Abrasion and puncture injuries are more important than impact injury for papayas.

Chilling injury symptoms include pitting, blotchy coloration, uneven ripening, skin scald, hard core (hard areas in the flesh around the vascular bundles), water soaking of tissues, and increased susceptibility to decay. Increased alternaria rot was observed in mature-green papayas kept for 4 days at 2°C, 6 days at 5°C, 10 days at 7.5°C, or 14 days at 10°C. Susceptibility to chilling injury varies among cultivars and is greater in mature- green than ripe papayas (10 vs. 17 days at 2°C; 20 vs. 26 days at 7.5°C).

Heat injury. Exposure of papayas to temperatures above 30°C (86°F) for longer than 10 days or to temperature-time combinations beyond those needed for decay and/or insect control result in heat injury (uneven ripening, blotchy ripening, poor color, abnormal softening, surface pitting, accelerated decay). Quick cooling to 13°C (55°F) after heat treatments minimizes heat injury.

Heat Treatments for Insect Control

Hot water treatment: 30 minutes at 42°C (107.6°F) followed within 3 minutes by a 49°C (120.2°F) dip for 20 minutes.

Vapor heat treatment: Fruit temperature is raised by saturated water vapor at 44.4°C (112°F) until the center of the fruit reaches that temperature, and then held for 8.5 hours.

Forced hot air treatment: 2 hours at 43°C (109.4°F) + 2 hours at 45°C (113°F) + 2 hours at 46.5°C (115.7°F) + 2 hours at 49°C (120.2°F).


Anthracnose caused by Colletotrichum gloesporioides, is a major cause of postharvest losses. Latent infections of unripe papayas develop as the fruits ripen. Lesions appear as small, brown, superficial, water soaked lesions that may enlarge to 2.5 cm (1 inch) or more in diameter.

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Black stem-end rot caused by Phoma caricae-papayae attacks fruit pedicel. After harvest, the disease lesion on fruits appear in the stem area which becomes dark-brown to black. Another stem-end rot is caused by Lasiodiplodia theobromae.

Phomopsis rot caused by Phomopsis caricae-papayae begins in the stem end or a fruit skin wound and can develop rapidly in ripe fruits; invaded tissue softens and darkens slightly.

Phytophthora stem-end rot caused by Phytophthora nicotianae var. parasitica begins as water-soaked areas followed by white mycelium that become encrusted.

Alternaria rot caused by Alternaria alternata follows chilling injury of papayas kept at temperatures below -12°C (54°F).

Control Strategies: 1. Careful handling to minimize mechanical injuries 2. Prompt cooling and maintenance of optimum temperature and relative humidity

throughout postharvest handling operations. 3. Application of fungicides, such as thiabendazole (TBZ). 4. Dipping in hot water at 49°C (120°F) for 20 minutes.

Pineapple

Maturity Indices

Change of shell color from green to yellow at the base of the fruit. Pineapples are non-climacteric fruits and should be harvested when ready to eat. A minimum soluble solids content of 12% and a maximum acidity of 1% will assure minimum flavor acceptability by most consumers.

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Quality Indices

Uniformity of size and shape; firmness; freedom from decay; freedom from sunburn, sunscald, cracks, bruising, internal breakdown, endogenous brown spot, gummosis, and insect damage.

Tops (crown leaves): green color, medium length, and straightness.

Range of soluble solids = 11-18%; titratable acidity (mainly citric acid) = 0.5-1.6%; and ascorbic acid = 20-65 mg/100g fresh weight, depending on cultivar and ripeness stage.

Optimum Temperature

10-13°(50-55°F) for partially-ripe pineapples 7-10°C (45-50°F) for ripe pineapples.


85-90%

Rates of Respiration Production Temperature 7°C(45°F) 10°C(50°F) 13°C(55°F) 15°C(59°F)ml CO2/kg·hr 2-4 3-5 5-8 8-10



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Less than 0.2 µl C2H4/kg·hr at 20°C (68°F)


Exposure of pineapples to ethylene may result in slightly faster degreening (loss of chlorophyll) without influencing internal quality. Pineapples must be picked when ripe because they do not continue to ripen after harvest.

Responses to Controlled Atmospheres (CA) 3-5% O2 and 5-8% CO2 Benefits of CA include delayed senescence and reduced respiration rate

Atmospheres (CA) Postharvest life potential: 2-4 weeks in air and 4-6 weeks in CA 10°C (50°F),

depending on cultivar and ripeness stage Exposure to O2 levels below 2% and/or CO2 levels above 10% should be avoided

because of the potential for development of off-flavors. Waxing may be used to modify O2 and CO2 concentrations within the fruit enough

to reduce incidence and severity of endogenous brown spot.


Chilling injury. Exposure of pineapples to temperatures below 7°C (45°F) results in chilling injury. Ripe fruits are less susceptible than unripe or partially-ripe fruits. Symptoms include dull green color when ripened (failure to ripen properly), water-soaked flesh, darkening of the core tissue, increased susceptibility to decay, and wilting and discoloration of crown leaves.

Endogenous Brown Spot (EBS) or Black Heart. EBS is usually associated with exposure of pineapples before or after harvest to chilling temperatures, e.g. below 7°C (45°F) for one week or longer. Symptoms are water-soaked, brown areas that begin as spots in the core area and enlarge to make the entire center brown in severe cases. Waxing is effective in reducing chilling injury symptoms. A heat treatment at 35°C (95°F) for one day has been shown to ameliorate EBS symptoms in pineapples transported at 7°C (45°F) by inhibiting activity of polyphenol oxidase and consequently tissue browning.

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Thielaviopsis rot (black rot, water blister). Caused by Thielaviopsis paradoxa, may start at the stem and advance through most of the flesh with the only external symptom being slight skin darkening due to watersoaking of the skin over rotted portions of the flesh. As the flesh softens, the skin above readily breaks under slight pressure.

Yeast fermentation. Caused by Saccharomyces spp, is usually associated with overripe fruit. The yeast enters the fruit through wounds. Fruit flesh becomes soft and bright yellow and is ruptured by large gas cavities.

Control Strategies:

1. Careful handling to minimize mechanical injuries 2. Prompt cooling and maintenance of optimum temperature and relative humidity

throughout postharvest handling operations. 3. Application of fungicides, such as thiabendazole (TBZ).

Plantain Banana

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Maturity Indices

Maturity can be judged by the angularity of the fingers. Plantains are harvested mature-green and may or may not be ripened upon arrival at destination markets since plantains are eaten both at the mature-green stage and when fully yellow.

Quality Indices Finger size (minimum length of 22 cm = 9 inches) Freedom from mechanical damage, scars, insect damage, disease and chemical

residues.

Optimum Temperature

7.2 – 10˚C (45-50˚F) for up to 7 days10 – 12˚C (50-54˚F) for longer than 7 days


90-95%


Temperature 7.2°C(45°F) 10°C(50°F) 12.5°C(54.5°F) 14°C(57.2°F) 20°C(68°F) ml CO2/kg·hr1, 2 3-21 2-15 6-15 8-12 7-107

1Low end for mature-green plantains and high end for ripening plantains.


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Temperature 7.2°C(45°F) 10°C(50°F) 12.5°C(54.5°F) 14°C(57.2°F) 20°C(68°F) µl C2H4/kg·hr1 0.01-0.05 0.01-0.26 0.01-0.11 0.01-0.12 0.01-2.58

1Low end for mature-green plantains and high end for ripening plantains.


Ethylene stimulates ripening of plantains. Thus, plantains that are marketed mature-green should be protected from exposure to ethylene. Plantains that are marketed ripe should be ripened with bananas (exposure to 100-150 ppm ethylene for 24-48 hours at 15-20°C = 59-68°F and 90-95% relative humidity).

Responses to Controlled Atmospheres (CA) Optimum CA: 2% O2 and 5-10% CO2

CA delays ripening, reduces respiration and ethylene production rates, and maintains overall appearance of the fruit.

CA may decrease the occurrence of subepidermal browning at marginally low temperatures.


Chilling Injury. Symptoms include peel browning, dull or smokey peel coloration, subepidermal vascular browning, abnormal ripening (possible acceleration); and in severe cases failure to ripen. Chilling injury results from exposure of plantains to temperatures less than or equal to 7.2 °C (45°F) for 7 or more days, depending on cultivar, maturity, and temperature. Chilled fruit are more sensitive to mechanical damage and postharvest decay.

Physical Disorders

Skin abrasions. Abrasions result from skin scuffing against other fruit, surfaces of handling equipment, or shipping boxes. When exposed to low relative humidity conditions (<90%), water loss from scuffed areas is accelerated and peel color turns brown and in severe cases black, which is similar to severe peel browning associated with chilling injury.

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Impact bruising. Dropping of plantains may induce browning of the flesh with or without damage to the skin. In some cases, damaged areas may become infected with fungal growth.


Crown rot. This disease is caused by one or more of the following fungi: Thielaviopsis paradoxa, Lasiodiplodia theobromae, Colletotrichum musae, Deightonialla torulosa, and Fusarium roseum – which attack the cut surface of the hands. From the rotting hand tissue the fungi grow into the finger neck and with time, down into the fruit.

Anthracnose. Caused by Colletotrichum musae, becomes evident as the bananas ripen, especially in wounds and skin splits.


Cigar-end rot. Caused by Verticillium theobromae and/or Trachysphaera fructigena. The rotted portion of the plantain finger is dry and tends to adhere to fruits (appears similar to the ash of a cigar).

Control strategies. Minimizing bruising; prompt cooling to 12°C (54°F); proper sanitation of handling facilities; hot water treatments (such as 5 minutes in 50°C (122°F) water and/or fungicide (such as Imazalil) treatment to control crown rot.

Pomegranate

Maturity Indices External red color (depending on cultivar) Red color of juice (equal to or darker than Munsell color chart 5R-5/12) Acidity of juice below 1.85%

Quality Indices Freedom from growth cracks, cuts, bruises, and decay Skin color and smoothness Flavor depends on sugar/acid ratio which varies among cultivars. A soluble solids

content above 17% is desirable Tannin content below 0.25% is desirable

Optimum Temperature

5°C (41°F) for up to 2 months; longer storage should be at 7.2°C (45°F) to avoid chilling injury.

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90-95%; pomegranates are very susceptible to water loss resulting in shriveling of the skins. Storing fruit in plastic liners and waxing can reduce water loss, especially under conditions of lower relative humidity.


Temperature 5°C(41°F) 10°C(50°F) 20°C(68°F)ml CO2/kg·hr 2-4 4-8 8-18



Less than 0.1 µl/kg·hr at 10°C (50°F) or lower Less than 0.2 µl/kg·hr at 20°C (68°F)


Exposure to ethylene at 1 ppm or higher stimulates respiration and ethylene production rates, but it does not affect their quality attributes. Pomegranates do not ripen after harvest and must be picked fully ripe to ensure the best eating quality.


Very few studies of the responses of pomegranates to CA have been conducted. Storage in 2% O2 reduces chilling injury if pomegranates are kept below 5°C (41°F). In one study, pomegranates were stored successfully at 6°C (43°F) in 3% O2 + 6% CO2 atmosphere for 6 months. In another study a combination of 5% O2 + 15% CO2 was found to be effective in decay control and scald prevention for up to 5 months at 7°C (45°F).


Chilling Injury. External symptoms include brown discoloration of the skin and increased susceptibility to decay. Internal symptoms include a pale color of the arils (pulp around the seeds) and brown discoloration of the white segments separating the arils.

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Chilling injury occurs if pomegranates are exposed for longer than one month at temperatures between their freezing point -3 °C (26.6°F) and 5°C (41° F) or longer than two months at 5° C (41 °F).

Husk Scald. Brown discoloration of the husk (without any internal symptoms on the arils or surrounding tissues) that occurs during storage for more than 3 months at 7°C (45°F) or lower temperatures.


Heart Rot. This may be caused by Aspergillus spp. and Alternaria spp. Affected fruit show a slightly abnormal skin color, and internally a mass of blackened arils. The disease develops while the fruit is on the tree. Affected pomegranates can be detected and removed by sorters in the packinghouse.

Orange

Maturity Indices

Soluble solids/acid ratio of 8 or higher and yellow-orange color at least on 25% of the fruit surface or soluble solids/acid ratio of 10 or higher and green-yellow color on 25% or greater of the fruit surface.

Quality Indices

Color intensity and uniformity; firmness; size; shape; smoothness; freedom from decay; and freedom from defects including physical damage (abrasions and bruising ), skin blemishes and discoloration, freezing damage, chilling injury, and insect damage. Flavor quality is related to soluble solids/acid ratio and absence of off-flavor-causing compounds including fermentative metabolites.

Optimum Temperature

3-8°C (38-46°F) for up to 3 months, depending on cultivar, maturity-ripeness stage at harvest and production area. Some Florida-grown cultivars can be kept at 0-1°C (32-34°F). Arizona-grown Valencia oranges should be kept at 9°C (48°F).


90-95%


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Temperature 5°C (41°F) 10°C (50°F) 15° (59°F) 20° (68°F)ml CO2/ kg·hr 2-4 3-5 6-12 11-17



< 0.1 µl/kg·hr at 20°C (68°F)


Exposure to 1-10ppm ethylene for 1-3 days at 20-30°C (68-86°F) may be used for degreening oranges. This treatment does not influence the internal quality (including soluble solids/acid ratio) and may accelerate deterioration and decay incidence.


A combination of 5-10% O2 and 0-5% CO2 can be useful for delaying senescence and for firmness retention but does not have a significant effect on decay incidence and severity, which is the limiting factor to long-term storage of oranges. Fungistatic levels (10-15%) of CO2 are not used because they may result in off-flavors due to accumulation of fermentative metabolites. Commercial use of CA on oranges during storage and transport is very limited.


Chilling injury. Symptoms include pitting, brown staining, and increased decay incidence. Minimum safe temperature depends on cultivar, production area, and maturity-ripeness stage at harvest. Severity of symptoms can be reduced if water loss is minimized (by waxing or film wrapping) and if decay-causing fungi are controlled (by use of fungicides and/or biological antagonists).

Stem-end rind breakdown. Symptoms include shriveling and peel injury around the stem due to aging.

Rind staining. This disorder results from overmaturity at harvest. It can be reduced by preharvest application of gibberellic acid that delays senescence.

Oil spotting (Oleocellosis). Harvesting and handling turgid oranges can result in release of oil that damages surrounding tissues. Thus, oranges should not be harvested when fully turgid such as early in the morning and soon after rain or irrigation.


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Important Diseases: Green mold (Penicillium digitatum) Blue mold (Penicillium italicum) Phomopsis stem-end rot (Phomopsis citri) Stem end rot (Lasiodiplodia theobromae) Brown rot (Phytophthora citrophthora) Sour rot (Geotrichum candidum)

Control Strategies: Minimizing physical damage during harvesting and handling. Treatment with postharvest fungicides and/or biological antagonists. Also, heat

treatments may be used. Prompt cooling and subsequent maintenance of optimum temperature and relative

humidity throughout marketing operations. Removal and/or exclusion of ethylene. Effective sanitation procedures throughout postharvest handling.

Pawpaw

Pawpaw (Asimina triloba; family Annonaceace) is the largest edible fruit native to the eastern U.S. The fruit ripens between mid August and mid October, depending on genotypes and growing location.

Maturity Indices

The only way to detect if ripening has commenced is to gently press or squeeze the fruit to determine if softening is evident. Some cultivars exhibit a change in skin color from darker to lighter green or even to yellow, and some also exhibit some skin browning or darkening at more advanced stages of ripening. Flesh may be cream-colored, yellow, or light orange, depending on cultivar, when fully ripe. Ripening is accompanied by an increase in soluble solids including sugars (sweetness) and significant aroma production. Pawpaws should be picked when flesh softening is first evident, as they ripen rapidly and become too soft to handle within 3 to 5 days.

Quality Indices

Green to yellowish-green skin, firm fruits with minimal brown discoloration on the skin.

Soft, custard-like flesh Sweetness (glucose, fructose and sucrose) at >18-20% soluble solids Intense aroma reminiscent of banana, mango, and/or pineapple. Free of bruises and decay

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Optimum Temperature

0-4°C (32-40°F) for a maximum of 4 weeks

Lower temperatures within this range and especially longer periods of cold storage may induce chilling injury.


90-95%


Respiration at harvest may be 50-100 mg CO2/ kg•hr at 20°C (68°F), and may increase 2- to 5-fold to a peak within 3 days.


Ethylene production at harvest may be 1-4 µg/kg•hr at 20°C (68°F), and it may increase to 5-15 µg/kg•hr within 3 days.

Pawpaw exhibits increasing respiration and ethylene production with peak values within 3 days after harvest indicating it is a climacteric fruit.


Field and laboratory studies to date using chemicals, atmospheric modification, or heat treatments that have been effective at modifying ripening behavior in many climacteric species via effects on ethylene biosynthesis or action have failed to appreciably alter ripening of pawpaw.


There is no information on their response to CA storage.

Physiological and Physical Disorders

Chilling Injury. Both skin and internal flesh browning of pawpaw have been observed by 6 weeks at 0-4°C (32-40°F).

Physical Injury. Similar to wound-induced browning in banana, pawpaws can be bruised during ripening. Thus, gentle handling to minimize bruising is essential to reducing postharvest losses.

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Shriveling. Symptoms become visible by 6 weeks of cold storage.

Speciality Banana

Maturity Indices

Degree of fullness of the fingers, i.e. disappearance of angularity in a cross section. Specialty bananas are harvested mature-green and are ripened upon arrival at destination markets.

Quality Indices

Maturity (the more mature the better the quality when ripe); finger length (dependent on cultivar); freedom from defects, such as insect injury, physical damage, scars and decay. As specialty bananas ripen, their starch content is converted into sugars (increased sweetness). Other constituents that influence flavor include acids and volatiles.

Optimum Temperature

Varies among cultivars:

‘Petite’ and ‘Yangambi’ 11°C (52°F) for up to 7 days ‘Red Macabu’ 10°C (50°˚F) for up to 7 days

‘Petite’ and other cultivars 12.5°-14°C (54.5-57.2°F) for longer than 7 days

Optimum Relative Humidity:

90-95%





`Petite' Cultivar

Temperature 10°C(50°F) 12.5°C(54.5°F) 14°C(57.2°F) 20°C(68°F) ml CO2/kg·hr1, 2 12-17 22-45 24-53 79-130

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Temperature 10°C(50°F) 12.5°C(54.5°F) 14°C(57.2°F) 20°C(68°F) ul C2H4/kg·hr1 0.09-0.16 0.2-0.9 0.2-0.7 1.1-2.1



Most commercial cultivars of bananas require exposure to 100-150 ppm ethylene for 24-48 hours at 15-20°C (59-68°F) and 90-95% relative humidity to induce uniform ripening. Carbon dioxide concentration should be kept below 1% to avoid its effect on delaying ethylene action. Use of a forced-air system in ripening rooms assures more uniform cooling or warming of bananas as needed and more uniform ethylene concentration throughout the ripening room.

Responses to Controlled Atmospheres (CA) Optimum CA: 2% O 2 and 5-10% CO 2 (dependent on cultivar) CA delays ripening, reduces respiration and ethylene production rates.


Chilling injury. Symptoms include peel browning, dull or smokey peel coloration, subepidermal vascular browning, abnormal ripening and in severe cases failure to ripen. Chilling sensitivity varies among cultivars. Chilling injury results from exposure of ‘Petite’bananas to temperatures lower than or equal to 10°C (50°F) for 7 or more days of storage or below 12.5°C (54.5°F) for 21 days of storage. ‘Yangambi’ bananas are subject to chilling injury when stored at temperates less than or equal to 10°C (50°F) for 7 days. ‘Red Macabu’ bananas are subject to chilling injury when stored for 5 days at temperatures below 10°C (50°F). Chilled fruit are more sensitive to mechanical damage and postharvest decay.

Physical Disorders

Skin abrasions. Abrasions result from skin scuffing against other fruit, surfaces of handling equipment, or shipping boxes. When exposed to low (<90%) relative humidity conditions, water loss from scuffed areas is accelerated and peel color turns brown and in severe cases black. This symptom is similar to severe peel browning associated with chilling injury.

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Impact bruising. Dropping of bananas may induce browning of the flesh with or without damage to the skin. In some cases, damaged areas may become infected with fungal growth.


Crown rot. This disease is caused by one or more of the following fungi: Thielaviopsis paradoxa, Lasiodiplodia theobromae, Colletotrichum musae, Deightonialla torulosa, and Fusarium roseum – which attack the cut surface of the hands. From the rotting hand tissue the fungi grow into the finger neck and with time, down into the fruit.

Anthracnose. Caused by Colletotrichum musae, becomes evident as the bananas ripen, especially in wounds and skin splits.


Cigar-end rot. Caused by Verticillium theobromae and/or Trachysphaera fructigena. The rotted portion of the banana finger is dry and tends to adhere to fruits (appears similar to the ash of a cigar).

Control strategies. Minimizing bruising; prompt cooling to 14°C (57°F); proper sanitation of handling facilities; hot water treatments (such as 5 minutes in 50°C (122°F) water and/or fungicide (such as Imazalil) treatment to control crown rot.

Strawberry

Maturity Indices

Based on berry surface color. US: minimum 1/2 or 3/4 berry surface showing red or pink color, depending on grade. Calif.: minimum 2/3 berry surface showing red or pink color.

Quality Indices

Appearance (color, size, shape, freedom from defects), firmness, flavor (soluble solids, titratable acidity and flavor volatiles), and nutritional value (Vitamin C). For acceptable flavor, a minimum of 7% soluble solids and/or a maximum of 0.8% titratable acidity are recommended.

Optimum Temperature

0 ± 0.5°C (32 ± 1°F)


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90 to 95%


Temperature 0°C (32°F) 10°C (50°F) 20°C (68°F)ml CO2/kg·hr 6 – 10 25 - 50 50 – 100

To calculate heat production, multiply ml CO2/kg·hr by 440 to get BTU/ton/ day or by 122 to get kcal/metric ton/day.

Rate of Ethylene Production

< 0.1 µl/C2H4/kg·hr at 20°C (68°F)

Response to Ethylene

Strawberries do not respond to ethylene by stimulation of ripening processes (strawberries should be harvested near to full ripe). Removal of ethylene from storage air may reduce disease development.

Responses to Controlled/Modified Atmospheres

Modified atmosphere packaging for shipment with 10 to 15% carbon dioxide reduces the growth of Botrytis cinerea (Grey Mold Rot) and reduces the respiration rate of the strawberries thereby extending postharvest life. Use of whole pallet covers for modified atmospheres is the most common method.


Perhaps because of rapid marketing and very short storage periods, physiological disorders are not a major concern with strawberry fruit.


Diseases are the greatest cause of postharvest losses in strawberries. Postharvest fungicides are not used on strawberries; therefore, prompt cooling, storage at 0°C (32°F), preventing fruit injury, and shipment under high carbon dioxide are the best methods for disease control. In addition, care should be taken to keep diseased or wounded berries out of trays at harvest as strawberry diseases will spread from diseased to nearby healthy berries (nesting).

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Irradiation has been tested on strawberries for decay control with mixed success. Doses needed for adequate decay control without high carbon dioxide generally result in excessive berry softening.

Botrytis Rot (Grey Mold). Caused by Botrytis cinerea is the greatest cause of postharvest strawberry losses. This fungus continues to grow even at 0°C (32°), however growth is very slow at this temperature.

Rhizopus Rot. Caused by the fungus Rhizopus stolonifer. Spores of this fungus are usually present in the air and are easily spread. This fungus will not grow at temperatures below 5°C (41°F), therefore temperature management is the simplest method of control.

Figure 1. Cooling and deterioration. Strawberries should be cooled as soon as possible after harvest; delays beyond 1 hour reduce the percentage of marketable fruit.

Watermelon

Maturity Indices

Watermelon (Citrullus lanatus Thunb.) are harvested at full maturity as they typically do not develop in internal color or increase in sugars after being removed from the vine. The ground spot (the portion of the melon resting on the soil) changes from pale white to a creamy yellow at proper harvest maturity. Another indicator used at harvest include a wilted but not fully desiccated vine tendril proximal to the stem-end attachment. Destructive sampling is used to judge maturity of a population of watermelons. For seeded cultivars, maturity is reached when the gelatinous covering (aril) around the seed is no longer apparent and the seed coat is hard. Cultivars vary widely in soluble solids at maturity. In general, a soluble solids content of at least 10% in the flesh near the center of the melon is an indicator of proper maturity if the flesh is also firm, crisp and of good color.

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http://postharvest.ucdavis.edu/Produce/ProduceFacts/Fruit/watermelon_graphics.shtml



Quality Indices

Watermelons should be symmetrical and uniform in appearance. The surface should be waxy and bright in appearance. Absence of scars, sunburn, transit abrasions or other surface defects or dirt. No evidence of bruising. Appears heavy for size.

U.S. grades Fancy, No. 1, and No. 2. Distinction among grades is based predominantly on external appearances.

Optimum Temperature

10 - 15°C (50 - 59°F ) Storage life is typically 14 days at 15°C (59°F) with up to 21 days attainable at 7-10°C (45-50°F).

For short-term storage or transit to distant markets (> 7 days), most recommendations use 7.2°C (45°F) and 85-90% R.H. as the acceptable handling conditions. Watermelons are, however, prone to chilling injury at this temperature. Extended holding at this temperature will induce chilling injury, rapidly evident after transfer to typical retail display temperatures.

Many watermelons are still shipped without precooling or refrigeration during transit. These fruit must be utilized for prompt market sales as quality declines rapidly under these conditions.


85-90 %; High relative humidity is generally advisable to reduce desiccation and loss of glossiness.


NA - not available

NR - not recommended due to chilling injury

Temperature

°C (°F) ml CO2 / kg·hr

0 32 NR 5 41 3-4 10 50 6-9 15 59 NA 20 68 17-25 25 77 NA

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Low - 0.1 - 1.0 µl / kg·hr at 20°C ( 68°F)


Exposure to an ethylene concentrations as low as 5ppm for 7 days at 18°C (64°F ) will cause unacceptable loss of firmness and eating quality.


Controlled atmosphere storage or shipping are not recognized as offering Controlled benefits for watermelon.


Chilling injury. Typically occurs after storage at temperatures < 7°C ( 45°F) Disorders for several days. Symptoms of chilling injury include pitting, decline in flesh color, loss of flavor, off-flavors and increased decay when returned to room temperatures.

Physical Injury

Improper handling and loading of bulk watermelons too often result in serious transit losses due to bruising and cracking. Internal bruising leads to premature flesh breakdown and mealiness.


Disease can be an important source of postharvest loss depending on season, Disorders region and local climatic conditions at harvest. Generally these losses are low in comparison with physical injury due to bruising and rough handling. Black Rot, caused by Didymella bryoniae, Anthracnose caused by Colletotrichum orbiculare, and Phytophthora Fruit Rot are common in areas with high rainfall and humidity during production and harvest An extensive list of stem-end, blossom-end, rind decay or surface lesions may occur, including the bacterium Erwinia and the fungal pathogens Alternaria, Botrytis, Cladosporium, Geotrichum, Rhizopus, and occasionally Mucor, Fusarium, and Tricothecium.

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Cut watermelon for slices or cubes for fresh-cut fruit salads have a very short period of optimal quality. Flesh becomes water-soaked and mealy. Varietal performance for fresh-cut is not currently available.

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Storing Fresh Fruits and Vegetables for Better Taste

The flavor of fruits and vegetables is influenced by maturity and quality at harvest and by how they are stored afterwards. To maintain the freshness and flavor of the produce you buy at the market or grow in your garden, it is important to know how to store it at home.Many fruits and vegetables should be stored only at room temperature because refrigerator temperatures (usually 38° to42°F [3.3° to 5.6°C]) damage them or prevent them from ripening to good flavor and texture. For example, when stored in the refrigerator, bananas develop black skin and do not gain good sweetness, and sweet

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potatoes take on off-flavors and a hard core when cooked after being refrigerated. Watermelons lose their flavor and deep red color if they are stored for longer than 3 days in the refrigerator. Pink tomatoes ripen to a better taste and red color if they are left at room temperature. In the refrigerator, they do not turn red, and even red tomatoes kept in the refrigeratorlose their flavor.Other produce can be ripened on the counter and then stored in the refrigerator.A few fruits and fruit-type vegetables gain sugar or soften when stored at room temperature. For example, Bartlett pears turn yellow and become softer and sweeter on the counter. After they have ripened they can be stored for 1 to 3 days in the refrigerator without losing taste.

Countertop Storage

The counter storage area should be away from direct sunlight to prevent produce from becoming too warm. Fruits and vegetables that can be stored at room temperature for a few days without shriveling do not lose moisture rapidly. Even so, moisture loss can be reduced by placing produce in a vented plastic bowl or a perforated plastic bag. Do not place produce in sealed plastic bags on the counter because this slows ripening and mayincrease off-odors and decay due to accumulation of carbon dioxide and depletion of oxygen inside the sealed bag. Ripening in a bowl or paper bag can be enhanced by placing one ripe apple with every 5 to 7 pieces of fruit to be ripened.Apples produce ethylene that speeds ripening. (Fuji and Granny Smith applesdo not produce much ethylene and donot enhance ripening.)

Refrigerator StorageRefrigerated fruits and vegetables should be kept in perforated plastic bags in the produce drawers of therefrigerator. You can either purchase perforated plastic bags or make smallholes with a sharp object in unperforated plastic bags (about 20 holes per medium-size bag). Separate fruits from vegetables (use one drawer for each group) to minimize the detrimental effects of ethylene (produced by the fruits) on the vegetables. Use all refrigerated fruits and vegetables within a few days since longer storage results in loss of freshness and flavor.

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*Ethylene production rate: **Ethylene sensitivity (detrimental effects include yellowing, softening,VL = very low (<0.1 μL/kg-hr at 20°C) increased decay, abscission or loss of leaves, browning)L = low (0.1=1.0 μL/kg-hr) L = low sensitivityM = moderate (1.0-10.0 μL/kg-hr) M= moderately sensitiveH = high (10-100 μL/kg-hr) H = highly sensitiveVH = very high (>100 μL/kg-hr)

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Criteria for Incoming Inspection for Fruit

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