AGRICULTURAL RESEARCH COMMUNICATION CENTRE

www.arccjournals.com / indianjournals.comAsian J. Dairy & Food Res., 32 (2) : 108-114, 2013

MODIFIED ATMOSPHERE PACKAGING AND STORAGE OF MUSHROOMS

Satish Kumar, Gagandeep Kaur, Sadhna Arora and Rohit Kumar

Department of Processing and Food EngineeringPunjab Agricultural University, Ludhiana 141004, India

Received: 29-09-2012 Accepted: 29-03-2013

ABSTRACTMushrooms were packed in different polymeric films viz PP, LDPE and Shrink films with three

different treatments viz film with perforations, film without perforations and with and without CO2flushing under room temperature and refrigerated conditions. The physiological loss in weight anddecay increased with storage time irrespective of treatments and temperature. Overall darkening ofcolour was observed during storage. The treatment with no perforations and without CO2 flushingunder room temperature and refrigerated conditions was found to be the best. Average hardnessand fracturability decreased with the increase in size of mushroom and period of storage. The LDPEfilm under room temperature conditions and PP film under refrigerated conditions was found best.The medium size (34.62 mm head dia) white button mushrooms can be stored in LDPE film for 2days at room temperature. The same mushroom can be stored in PP film under refrigerated conditionsfor 5 days.

Key words: Fracturability, Hardness, LDPE, Mushroom, PP, Perforations, Refrigerated, Shrink film, .

INTRODUCTIONMushroom cultivation has emerged as a

promising agro based, land independent enterprise.Mushrooms are valued for its characteristics meatybiting texture and flavour (Bano et a.l, 1992).Mushroom cultivation in India has witnessed atremendous change during the last one decade inrespect of types and strains of mushrooms cultivated,scale of cultivation, geographical regions, growingperiods and growing technology. Several bigcommercial units are coming into production besidesa large numbers of small and medium sized seasonalmushroom growers. There are around 38,000mushroom varieties known to exist, but only 100 ofthese are considered to be edible. Button mushroom( Agaricus bisporus) and oyster mushroom(Pleurotus spp.) constitute about 38% and 24%respectively of the world mushroom production(Anonymous.,1996). Punjab which occupies 1.53%of total area of India, contributes 25% of totalmushroom production in India (Sharma, 2002). Atpresent the production of mushroom in Punjab is45,000 tonnes (95% is white button mushroom) peryear which contributes more than 50 % (85,000

tonnes) of the total mushroom production of India(Khanna, 2007).

Mushroom is extremely perishable as itcontains about 90% (wb) moisture content. Somehave a life span of less than a day and others maysurvive one week. A group of tougher mushroomsmay last months but they have a tough woody texture.Various physiological and morphological changes(browning, texture loss, water loss) occur afterharvest which renders mushrooms unacceptable toconsumers. There are other factors like the size ofthe product, severity of preparation, maturity of theproduct and type of tissue that have an effect on theshelf-life of the packaged produce. Deterioration inquality of mushroom leads to reduction in consumeracceptability and market price.

Modified atmosphere packaging is a low costtechnique having a distinct advantage over othertechniques of preservation. MAP increases the shelflife of the perishables. MAP results in high RH withinthe package environment which diminishesdehydration and preserves freshness. But, lower O2and excessive CO2 levels would result in developmentof off flavors. High levels of CO2 have uniquefungicidal effect. Similarly excessive in-packagehumidity may stimulate microbial pathogendevelopment. The material of the film selected for

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packaging should be such that it provides optimumcondition for increasing the shelf life of the crop.Gormley and MacCanna (1967) reported wrinklingand brown patches on surfaces of uncoveredmushrooms due to excessive loss of moisture. Useof sorbitol resulted in better color mushrooms at 120C. Ahlawat et al. (1998) studied the effect ofdifferent anti-browning agents viz. EDTA, citric acid,calcium chloride, KMSand hydrogen peroxide incontrolling the browning in white button mushroom.Rai et al. (2000) observed increase in pileus andstipes and total sugar content for oyster mushroomspacked in micro-perforated film at 50C and 150C,while they reduce in ordinary oriented polypropylenefilm packages. Keeping this in view the present studyhas been planned to evaluate the suitability ofdifferent polymeric films for extending the shelf-lifeof mushrooms and the effect of size (Head Diameter)of mushroom on the storage behavior.

MATERIALS AND METHODSMushrooms cv. white Button were procured

from the PAU, Ludhiana mushrooms farm. Effortswere made to select mushrooms of uniform size andmaturity without any natural discloration on thesurface. The Mushrooms were washed with runningtap water to remove the dust or dirt from the surface.These were sorted to discard highly oversize andunder size mushroom to have a reasonable variationin dimension. Mushroom samples each weighing100 gms packed in different polymeric films viz. PP(20 m), LDPE (20 m), Shrink (15 m gauge) withthree different treatments viz. perforated (size 1.94mm) polymeric films, polymeric films withoutperforations and no CO2 flushing and polymericfilms with CO2 flushing).The samples were keptunder different environmental conditions viz. roomtemperature storage (20-30 0C and RH 70-80%) andrefrigerated storage (0-50C and RH 78%). The studywas conducted till the decay took place. Theparameters recorded were physiological loss inweight (PLW), color development of skin, decay,textural characteristics and head diameter.

Physiological loss in weight (PLW) wasdetermined on initial weight basis. Initial weight ofthe sample (100g) was packed and final weight wasnoted daily using the electronic weighing balancehaving least count of 0.5 kg. The PLW was calculatedas:

100(%) xWeightInitial

WeightFinalWeightInitialPLW

The decay was measured in terms of percentrotting. Two packs of 100 gm each mushroomspacked in different polymeric films with differenttreatments were kept for studies and observed dailyfor percent rotting. The color development of skinwas measured in terms of tristimulus parameters L,a, b using Hunter colorimeter model Miniscan XEplus. Three replications were taken for each sampleand a mean value was computed. The data in termof coordinates L, a and b were converted todifferent functions of color as hue value, chroma andtotal color dif ference (E) as follows(Gnanasekheran et al., 1992).

Hue angle = tan-1 (b/a)Chroma = (a2 + b2)1/2

Total Color Difference (E) = [(L - L0)2 + (a - a0)

2 +(b - b0)

2]1/2

Size of mushroom was determined with thehelp of digimatic caliper in terms of head diameterand stalk length. The textural properties are relatedto deformation, disintegration and flow of the foodunder a force and are measured objectively byfunctions of mass, time and distance. The texturalbehavior of mushrooms was estimated in terms oftexture profile analysis curve. Different headdiameters of mushrooms stored in LDPE films (bestfilm) at room temperature were studied using textureanalyzer (TA-Hdi) with load cell of 250 kg. Thehardness was calculated from the plot of cycliccompression test samples. The following settings wereemployed: Probe - P75 Compression, Pre testspeed:5 mm/s; Test speed:1 mm/s; Post speed: 10mm/s; Compression: 50% strain; Time: 5 sec. Beforeperforming the tests, the machine was calibrated forload and distance. From the force-time curve,hardness and first fracture point were noted.

RESULTS AND DISCUSSIONEffect of Film and Treatment on the Qualityof MushroomPhysiological loss in weight (PLW): The perusalof the Fig 1 showed that the PLW increased with theduration of storage irrespective of type of film ortreatment. The PP film recorded lowest PLW of1.61% compared to 2.16% 2.34% in LDPE andShrink film with perforations. Non-perforated films,with or without CO2 flushing, recorded lower PLWof 0.66% 1.50% compared to fi lms wi thperforations (1.61-2.34%). Among non perforated

110 ASIAN JOURNAL OF DAIRY AND FOOD RESEARCH

Storage duration (days) With perforation (WP)

Without perforation & no Co2 (WPNC)

Without perforation & with Co2 (WPC)

Ambient condition (Best fi lm: LDPE Film)

1 0.00 0.00 0.00

2 11.89 5.57 7.84

3 20.00 8.57 12.71

Cold storage (Best fi lm: PP Film)

1 5.00 0.00 0.00

3 7.50 2.86 5.82

5 28.50 14.29 20.77

TABLE 1: Decay (%) in mushroom under different storage environments

Fig 1 PLW in LDPE packed mushroom under ambient conditions.

0

0.5

1

1.5

2

2.5

0 1 2 3 4

Storage duration (days)

PLW

(%) WP

WPNCWPC

Fig 2 PLW in PP packed mushroom under cold storage conditions.

00.10.20.30.40.50.60.70.8

0 1 2 3 4 5 6

Storage duration (days)

PLW

(5) WP

WPNCWPC

without CO2 flushing, PP film had lowest PLWof 0.66% among different fi lms whereas shrinkfi lm recorded highest physiological loss inweight of 1.50%. Similar trend was observedin non perforated film with CO2 flushing where,the PLW was still lower (0.68% 1.35%). Highmoisture loss in perforated films may be causedby high rate of transpiration and respirationthrough un-interrupted atmospheric columnand under higher temperature and lowerrelative humidity compared to wrapped fruits(Singh and Singh, 1992) Mushrooms packedin polymeric fi lms stored under refrigeratedco nd i t i o ns reco rd ed much lower PLWcompared to room te