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Examples of products
Physiology of fresh-cut products
Preparation and handling
Quality aspects of fresh-cut products
Fresh-cut Products: Overview and Challenges
Marita [email protected]://postharvest.ucdavis.edu
"Fresh-cut produce" is defined as any fresh fruit or vegetable or any combination thereof that has been physically altered from its original form, but remains in a fresh state. Regardless of commodity, it has been trimmed, peeled, washed and cut into 100% usable product that is subsequently bagged or prepackaged to offer consumers high nutrition, convenience and value while still maintaining freshness.
Fresh-cut Produce
• Minimally Processed
• Lightly Processed
• Partially Processed
• Preprepared
• Fresh Processed
• Pre-cut
• Value-added
IFPA/UFPA
Source: The Perishables Group -
The FreshFacts on Fresh Cut, 2006
Fresh-cut Produce Sales via Supermarket Channels,* 2005,
$6 Billion Total
Packaged salads
53%Veggies* 26%
Fruit 21%
Carrots=50% of vegetables
*Data for 59.2% of grocery ACV, projectedto total grocery over $2 million/store channel.
Fresh-cut Products References (Summaries on Specific Products)
• FRESH-CUT FRUITS (J. Beaulieu, J. Gorny)
• FRESH-CUT VEGETABLES (M.Barth, H. Zhuang, M. Saltveit)
USDA Agric. Handbook 66. 2004. Commercial Storage of Fruits, Vegetables & Ornamentals (K.Gross et al., eds.); http://www.ba.ars.usda.gov/hb66
• FRESH-CUT FRUITS AND VEGETABLES (M. Cantwell &T. Suslow). 2002. Postharvest Technology of Horticultural Crops, Ch. 36.
The Magazine for Value-Added Producehttp://www.freshcut.com/
International Fresh-cut Produce AssociationTechnical publications on food safety, packaging;technical seminars, annual conference & expo
UNITED FRESH PRODUCE ASSOCIATIONhttp://www.unitedfresh.org/
2006
FreshFresh--cut Vegetablescut Vegetables• Lettuces: cleaned, chopped, shredded• Spinach, leafy greens, washed & trimmed • Broccoli & cauliflower florets• Cabbage, shredded • Carrots, baby, sticks, shredded• Celery sticks• Onions, whole peeled, slices, diced• Potatoes & other roots: peeled, sliced, diced• Mushrooms sliced• Jicama, Squash, cucumber slices, dices• Garlic, fresh peeled, slices
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Romaine; Caesar Salad
European style salads
Differentiation ofPrepared Salads; Salad Meals
Standard iceberg Plus “color”
Differentiation of Salads; Salad Meals
Standard iceberg Plus “color”About 1996
Salad kits, 2006
CARROT CHIPS™
CARROT DIPPERS™
CARROT SNACKSTM
for Horses!
http://www.grimmway.com
Food ServicePresentations
Sweetpotato for Food service
Strips taro, celeriac, sweetpotato
•Fresh Garlic •Whole Peeled Garlic Cloves •Roasted Garlic Cloves •Garlic Braids •Elephant Garlic •Jarred Garlic Products •Fresh Chopped Garlic •Chopped & Minced Garlic in Water
Resealable bags
Single serveSnack packs
Rigid containersand bowls
Biobased packagingPLA resin
Active packaging Intelligent/SmartPackaging
IFPA, 2004. Fresh-cut Produce Fuels an America on the go. 58 pp.
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Immediate Physical Effects
Mechanical shock to tissueBruises, cracks, fractures in tissue
Removal of protective epidermal layerAlter gas diffusionProvide entry for contaminants
Cell fluids on cut surface Reduced gas diffusionProvides substrate for microbes
Exposure to contaminantsMicrobial ,Chemical
Abrasion peeling of carrots leads to fragmented cell walls that dry out and result in “white blush”;can rehydrate carrots.
Diagrams from Saltveit, UC Davis
New equipmentautomatically peelsand then cuts the carrots;have less problem with“white blush”
Physiological Effects of Fresh-cut Processing
• Increased respiration rates
• Altered ethylene production rates
• Increases in other biochemical reactions– Discoloration and Color
– Texture
– Aroma and Flavor
– Nutritional quality
Main strategy to minimize changes in physiology is low temperature
Respiration rates of Intact and Shredded Lettuce
Res
pira
tion
(µ
l CO
2. g
-1 h
-1)
0
5
10
15
20
Days storage
0 1 2 3 4 5 6 7 8 9
Res
pira
tion
(µ
l CO
2. g
-1 h
-1)
0
5
10
15
20
Shredded Lettuce
Intact Lettuce2.5°C (36°F)
5°C (41°F)
7.5°C (45°F)
10°C (50°F)
Shredding greatly increased respiration rates Temperature control is
extremely important
• Low temperature minimizes wound response
• Diced onions discolor, decay, soften and lose fluid more readily than whole peeled onions
Storage Temperature
Res
pir
atio
n
(µL
CO
2. g
-1 h
-1)
0
1
2
3
4
5
6
7
8
9
10
11
12 Yellow Onion
Intact
Peeled
Diced
0°C 5°C 10°C
Average Respiration Rates (µL CO2/g-h)
40.629.318.110°C
21.217.410.65°C
Compressed Compressed Air PeeledAir Peeled
Manually Manually PeeledPeeled
Unpeeled Unpeeled ClovesCloves 0
10
20
30
40
50
Days0 2 4 6 8 10 12 14 16 18 20
Re
spir
atio
n (
l CO
2/g-h
)
0
10
20
30
40
50
5ºC (41°F)
Unpeeled Manually peeled Compressed air peeled
10ºC (50°F)
Res
pira
tion
(l C
O2/g
-h)
Careful peeling causes a substantial increase in respiration rates. Mechanical compressed air peeling doubles rates. Rates are significantly less at 5°C. Quality best maintained at 0°C.
0°C
Commercially Peeled Garlic Stored 9 Days
5°C 10°C 15°C
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Intact and Intact and FreshFresh--cut Kalecut Kale
Respiration rate (mL CO2 kg-1 h-1 )
Product 0ºC 5ºC 10ºC 15ºC
Full size leaves 8 12 29 33
Small leaves 14 21 42 57
Chopped (2 x 2 cm pieces full size leaves)
15 23 46 53
Shredded (0.3 cm pieces full size leaves)
17 28 59 68
Harvest Trim, core, defect removal Cool and/or MA Dump, mechanical cut Cooling, disinfection Drying, centrifugation Component blendingWeigh and package Metal detector, pack, palletize Temporary cold storage
Lettuce Salad Preparation
1. Harvest lettuce from first harvest results in better quality
trim outer leaves
2. Field-pack & local transport plastic bins or totes/ carton boxes or bins; avoid wood bins
transport on flatbed trucks; if distances far, transport in refrigerated trailer
3. Vacuum or forced-air cooling field temperatures and delay determine need to cool
vacuum and forced-air cooling most common
4. Reception, dump, trim and core revision and selection of heads on conveyer
further trimming outer leaves; removal of stem tissue with coring device
Preparation of Lettuce Salads
Often Done in the field
Preparation of Lettuce Salads, cont.
5. Chop/shred/tear continuous-feed cutter for salad pieces (3 x 3 cm) or shreds (<0.5 cm)
manual cutting for some lettuce types (romaine) very sharp knives reduce damage and subsequent browning
6. Wash and Cool Cold water containing disinfectant, usually chlorine
residence time form 15-30 sec; may use processing aides to reduce browning
7. Centrifugation or other drying technique vibration screens remove large volumes of water
centrifugation and air tunnels remove moisture so surface of product dry basket centrifuges of different sizes depending on product
8. Combine different products for salad mixes or “color” items may be added after washing and centrifuged together
In facility at low temperature 3-5°C
Preparation of Lettuce Salads, cont.
9. Package in plastic film bags centrifuged product dumped onto conveyor feeding filler
manual or automated form-fill-seal machines vacuum or gas-flushing with nitrogen
check for leakers in pressurized water chamber
10. Box, palletize and store temporarily Bags through a metal detector, conveyor to boxing and palletizing area
Temporary storage <5ºC (<41ºF); 0°C (32°F) is optimum
11. Transport to food service outlets and/or retail markets Pre-cooled clean trucks; thermostat at <5°C (41°F) Load at enclosed docks to maintain cold chain
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Washing Disinfecting Rapid cooling Cut to 2 inch sections Mechanical Peeling Mechanical shaping Disinfection Cooling Computerized quality and color sorting Packaging (form, fill, seal)
Processing Baby Peeled Carrots
Onion ProcessingRaw material qualityPackaging and odorsPhysical damageTemperature control
Many large volume (lettuces) products are mechanically cut, but manual preparation generally results in superior quality
cutting romaine by hand; eliminate defects manually peeled garlic vs compressed air peeled broccoli and cauliflower florets manually trimmed manually trimmed and cut melons, pineapples
SANITARY PLANT DESIGNFocus: Implementation of GMP’s
Rudi Groppe; http://www.heinzen.com/products/
Design efficient, easy to clean & sanitize processing plants
Mobility of equipment 2-3 areas to separate production steps
Total Microorganisms at Different Steps Total Microorganisms at Different Steps of a Freshof a Fresh--cut Salad Process Linecut Salad Process Line
Bin Dump 92,000
Coring Belt 210
Cutter 2,290
Transfer Belt 40
Cooling Water 5
Centrifuge 10
Package Filler 3,350
Operation Number/Sq. Inch
Modified from Hurst, Univ. Georgia, 1990
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Fresh-cut Products
Food Safety Requirements
•• Meticulous cleanliness of equipment, Meticulous cleanliness of equipment, employees and productemployees and product
•• Rigid maintenance of refrigerated Rigid maintenance of refrigerated temperaturestemperatures
•• Complete integrity of packagesComplete integrity of packages
•• Strict adherence to product use by dates Strict adherence to product use by dates & handling instructions& handling instructions
“Best if used” by datesUSDA Inspection guidelines but no standards
Wounds induce Wounds induce phenolicphenolic metabolismmetabolismLeading to unsightly brown pigmentsLeading to unsightly brown pigments Enzymatic Browning
PALPhenylalanine cinnaminc acid other phenolics
PPO+ O2 (o-Diphenol oxidase)
(Laccase)
complex brown polymers quinones
PAL = phenylalanine ammonia-lyasePPO = polyphenol oxidase
5
4
3
2
1
Salad Lettuce Cut edge browningWound induction of PAL
and brown pigments Lettuce types and varieties
differ in PAL and browning
Days at 5°C (41°F)
0 1 2 3 4 5 6 7
PA
L
acti
vit
y (
µm
ol c
inn
am
ic a
cid
. g-1
. h-1
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0Green LeafRed LeafButterhead
IcebergRomaine
5% LSD
Days at 5°C (41°F)
1 2 3 4 5 6 7 8
Res
pira
tion
rate
(µ
L/g-
h)
0
3
6
9
12
15
18
21 A. Intact leavesHeart Young Midsize Full size
Days at 5°C (41°F)
1 2 3 4 5 6 7 8
B. Salad-cut leaves (2 x 2 cm)
Romaine lettuce: leaf position/age effect on respiration, discoloration and composition
Phenolics highest in outer leaves; browning highest in outer leaves Sugars highest in heart leaves Chlorophyll/carotenoids highest in outer leaves Vitamin C not much affected by leaf age or position
Ermen, Hong, Cantwell, 2006
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Control
1-MCP
Air CAcv Pic
Nov 2004, 1000ppb 1-MCP at 5°C; 8hr after harvest, CA=1%O2+9%CO2
4 days 5°C
Prevention of enzymatic/oxidative browning
• Refrigeration (slows enzymatic reactions)
• Exclusion of oxygen (CA, MAP, edible films)
• Inhibition of PAL (lettuces & vegs)
• Inhibition of PPO (fruits)
• Use of reducing agents (ascorbic acid, etc.)
• Other chemical agents
Packaged Salad Quality Study
• 4 salad products from 5 processors• 4 production dates, product purchased• Products stored at 5°C (41°F)• Components: Size, Color
• Visual Quality and defects: 0, 10, 15 & 20d
• Composition: Sugar, Vit C, EtOH, Acetald.
• Gas Analyses: O2, CO2, C2H4,every 5 days
• Microbiological Tests: APC, Coliforms (0, 10, 20d)
• Sensory: 18 panelists, 5 criteria (texture, aroma, flavor, visual, Buy), 0 & 10D
Flavor quality good to 10 days; shelf-life expected 14-16 days
%
0.00
0.05
0.10
0.15
0.20
Days
0 4 8 12 16 20 24
%
0
5
10
15
20
25
mm
ol/k
g
0.0
0.5
1.0
1.5
2.0
Days
0 4 8 12 16 20 24
mm
ol/k
g
0
10
20
30
40
50
60
Sco
re (
9=
exc
elle
nt)
1
2
3
4
5
6
7
8
9
Days
0 4 8 12 16 20 24
Sco
re (
5=
seve
re)
0
1
2
3
4
5
Oxygen
Carbon Dioxide Ethanol
Acetaldehyde Visual Quality
Off-Odors
Temperature Effects on Salad Products
0ºC10ºC
20ºC
Peiser & Cantwell
Total Vitamin C (AA+DHA)
Days
0 3 6 9 12 15
Tot
al V
it. C
(m
g/1
00g
fwt.
)
0
10
20
30
40
air
1% O2 + 10% CO2
air + 10% CO2
1% O2
Ascorbic acid (AA)
Days
0 3 6 9 12 15
Dehydroascorbic acid (DHAA)
Days
0 3 6 9 12 15
LSD = 4.2
Romaine Salad-cut lettuce Vitamin C content and modified atmospheres
H. Ermen, G. Hong, M. Cantwell 2006
High CO2 atmospheres result in decreased Vitamin CHigh CO2 also reduces crispiness of lettuce
Lettuce AlternativesIntact Baby sizeClean Whole leavesHearts
Rely on temperatureNo modified atmospheres
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There are many opportunities There are many opportunities for damage to spinach leaves for damage to spinach leaves HarvestHarvest Bin dump, sort areaBin dump, sort area Wash and centrifugeWash and centrifuge Packing Packing
Information courtesy of Dr. G.S. Mudahar, Salad Time Farms, Inc.
3
4
5
6
7
0 2 3 4 5 6 7 8 9 10Days
Te
mp
erat
ure
(°C
)
1
At plant
Retail Store Cooler
Retail Shelf
DistanceTransport
LocalDistribution
Fresh-cut produce Chill Chain Temperatures During Shipping, Distribution and Retail Display.
We can do better!!
Good Temperature Control throughout handling and distribution is a Necessity for Fresh-cut Products
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Vegetable trays- want 18 day shelf-life
Products in tray and compatibility issues- raw material sourcing and handling before prepare - shelf-life of individual products in tray varies- temperature; 5°C too low for grape tomatoes- modified atmospheres—not good for all products in tray
FRUITSFRUITS
DaysVEGETABLESVEGETABLES
10-14Broccoli & cauliflower florets, shredded cabbage, lettuce and broccoli, celery & carrot sticks
4-9Pepper and tomato dices, cucumber slices, squash slices, mushroom slices, jicama sticks
>21Baby carrots, peeled onions, peeled garlic
2-9Strawberry slices, melon & mango cubes, citrus segments, peach & pear wedges, grape berries
10-14Apple wedges, pineapple chunks, pomegranate arils, kiwi slices
14-18Lettuce salads, lettuce separated leaves, lettuce mixes, spinach leaves, peeled potatoes
Potential post-cutting storage life at 2-5ºC (36-41ºF)
Products
Baby Carrots and Variety Selection
• Uniform, bright orange color
• Small or no core
• High sugars with no harshness/bitterness
• Smooth exterior to minimize peeling loss
• No green should or green core problems
• Strong tops for mechanical harvest
• Balance between juicy texture and resistance to shatter
Diced tomato: Example of variation in appearance of 5 cultivars
Fresh-cut tomato for food service
Stage of maturity/ripeness for cuttingColorTexture; slice integrityComposition-flavor
Brassicas have higher respiration rates than lettuces.Freshness of color and flavor ingredients.
High Quality Raw Material is Necessary
for High Quality Fresh-cut Product
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Preprocessing StorageExample: Lettuce heads stored at 5°C (41°F)Longer heads are stored, greater browning on cut salad pieces
Days after processing
1=no
ne,
5=
seve
re
1
2
3
4
5
Days stored before processing
Days after processing
0
7
14
IcebergLettuce
Browning of Cut Edges
RomaineLettuce
4 8 12 4 8 12
Meal SolutionsProtein componentStarch component
Current Fresh-cut Challenges
Fresh-cut FruitsApplesMelonsPineappleCitrus
12% 1%2%
2%3%
3%
48%
9%8%
14%
ApplesOther MelonsWatermelonHoneydewsCitrusTropicalsPineappleCantaloupeMixedOtherSource: The Perishables Group
Supermarket Mix of Value-Added Fresh Fruit: Quantity Sold, 2004
64,000,000 Pounds64,000,000 Pounds
29,000,000 Kg29,000,000 Kg
1.5 Million/19Kg Boxes1.5 Million/19Kg Boxes
1.5% USA Apple 1.5% USA Apple SupplySupply
13,500 13,500 McDMcDRestaurantsRestaurants
FreshFresh--Cut Cut Apples
From Jim Gorny
Commercial Pomegranate Aril Extraction and Packaging
From Adel Kader
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Ripeness Stage
& Storage Temperature
Effects
Shelf-life
Enzymatic Browning
PALPhenylalanine cinnaminc acid other phenolics
PPO+ O2 (o-Diphenol oxidase)
(Laccase)
complex brown polymers quinones
PAL = phenylalanine ammonia-lyasePPO = polyphenol oxidase
Genotypic Differences in Browning Potential of Apples Challenges for Fresh-cut Melon products
• Maturity: sugars vs firmness
• Taste-life vs Shelf-life
• Color
• Texture
• Flavor
31.732.232.4Color (chroma) (0.7)
7.910.511.5Soluble Solids (%) (0.6)
6.39.310.7Firmness (N)* (LSD=0.3)
SunburnGround Spot
Good QualityParameter
Sunburn
Ground Spot
Good QualityMelon Defects
andInternal Quality
* 5 mm diameter probe
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0°C 5°C 10°C 12d
10 days
7.5°C (45°F)
5°C (41°F)
2.5°C (36°F)
Relative Importance of Temperature and Modified Atmospheres for Fresh-cut melon
Air 1% O2 Air +10% CO2
1% O2 +10% CO2
Vis
ual
Qu
alit
y
1
2
3
4
5
6
7
8
9
Days
0 5 10 15
Off
-od
ors
1
2
3
4
5
Days
0 5 10 15
Air CA
Air CA
0°C 32°F2.5° 36°5° 41°7.5° 45°10° 50°
Fresh-cut Cantaloupe: Temperature and Atmosphere
CA 3%O2 +10%CO2 Cantwell, unpublished
Translucency not reduce firmnessCalcium chloride dips reduce translucency
10C (50F)
5C (41F)
Experimentally InducedTranslucency
BL=blunt blade SH = sharp blade
Translucency Defect• Differences among melon cultivars• Probably growing & nutrient conditions affect
A) Increased Technical & Managerial A) Increased Technical & Managerial SophisticationSophistication
B) Understand & Manage Fruit B) Understand & Manage Fruit Ripening Ripening
C) Overcome Sourcing IssuesC) Overcome Sourcing Issues
D) Reduce Labor CostsD) Reduce Labor Costs
E) Retain Flavor and AromaE) Retain Flavor and Aroma
The Successful FreshThe Successful Fresh--cut Fruit Processorcut Fruit Processor
Management of Ripening of Intact and Fresh-cut Fruits - Considerations
1. Stages of fruit developmentStages of fruit development
2.2. Fruits that must ripen on the plantFruits that must ripen on the plant
3.3. Fruits that can ripen on or off the Fruits that can ripen on or off the plantplant
4.4. Role of ethylene in fruit ripeningRole of ethylene in fruit ripening
5.5. Efficacy of 1Efficacy of 1--methylcyclopropene in methylcyclopropene in extending shelfextending shelf--life of freshlife of fresh--cut fruitscut fruits
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Cut ripe pineapple cubes have a longer post-cutting life than those cut green
Adel Kader
Classification of fresh-cut fruit products according to their potential post-cutting-life at optimum handling conditions (0-5ºC and 90-95% RH)
Banana slices, citrus segments, grape berries, melon cubes, nectarine and peachwedges, papaya cubes, pear wedges, persimmon slices, strawberry slices
2-9 days
Apple wedges, kiwifruit slices, mango cubes, pineapple slices and wedges, pomegranate arils
10-14 days
Fresh-cut fruit productsPotential
storage-life
Fresh-cut FruitRoadblocks to Success
• Labor Intensive Production
• High Cost per pound-yields and price
• Fruit availability– Offshore
– Stage of ripeness
• Perishability of cut product
Adapted from Jim Gorny
A)A) Modes of Failure: Modes of Failure:
Browning, Softening, Microbes Browning, Softening, Microbes
B) CultivarB) Cultivar
C) Maturity at CuttingC) Maturity at Cutting
D) Storage HistoryD) Storage History
ShelfShelf--life Driverslife Drivers
Maintain Quality & Shelf-life of Fresh-cut
Vegetable Products Use highest quality raw material
Minimize mechanical damage; sharp knives
Rinse cut surfaces; remove excess water
Maintain strict sanitation; chlorinated water
Use appropriate package and atmosphere
Maintain product temperature at 1-2°C
Fresh-cut ProductsOpportunities and Challenges
• Packaging; MAP
• Nutritional Quality
• Sensory Quality
• Microbial Food Safety
• Temperature Control
• Raw Material Quality
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