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Scientia Horticulturae 182 (2015) 1–7

Contents lists available at ScienceDirect

Scientia Horticulturae

journa l h om epage: www.elsev ier .com/ locate /sc ihor t i

omparative study of MAP and shrink wrap packaging techniques forhelf life extension of fresh guava

ihar R. Sahooa, Manoj K. Pandaa, Lalit M. Balb,∗, Uma S. Pala, Dipika Sahooc

Department of Agricultural Processing and Food Engineering, Orissa University of Agriculture and Technology, Bhubaneswar, Odisha 751003, IndiaPost Harvest Process and Food Engineering, College of Agriculture, Jawaharlal Nehru Agricultural University, Tikamgarh, Madhya Pradesh 472001, IndiaDepartment of Horticulture, College of Agriculture, Bhawanipatna, Orissa University of Agriculture and Technology, Bhubaneswar, Odisha 751003, India

r t i c l e i n f o

rticle history:eceived 13 August 2014eceived in revised form 14 October 2014ccepted 15 October 2014

eywords:uavaAP

hrink wrap packaging

a b s t r a c t

Effect of packaging techniques and storage environment was assessed for maintaining quality and shelflife of guava. Changes in headspace gases, physiological loss in weight (PLW), ascorbic acid, texture,colour and subjective quality were evaluated. The in-pack guava created a suitable headspace with lowO2 and high CO2 concentrations, which resulted in a better retention of freshness of the guava. Shrinkpackaging with bi-axially oriented polypropylene (BOPP) could not yield better result under ambientstorage because of high water vapour transmission rate (WVTR) of the film and consequently loss ofturgidity of fruits. Modified atmospheric packaging (MAP) in polypropylene (PP) with pin holes wasfound to be the best followed by vacuum pack with PP in cold condition and could be used to store for

hysiological loss in weightarketability

28 and 24 days with maintenance of texture, colour, ascorbic acid and marketability. It is also inferredthat under ambient conditions guava could be stored for 4 days using low density polyethylene (LDPE)with pin holes and PP with pin holes as MAP storage. The research findings of the study would give aninnovative facet for fresh guava preservation and enhancing the commercial potential along with opennew avenues for fresh fruit and vegetable industry.

© 2014 Elsevier B.V. All rights reserved.

. Introduction

Guava (Psidium guajava L.) is an important fruit crop of sub-ropical and tropical regions of the world. It is successfully grownll over India and contributes 0.4% of total fruit production withstimated production of 1.75 million tonnes from 0.25 millionectares (Singh and Pal, 2008). There is tremendous demand of

ruit for fresh and processing purpose in both domestic and inter-ational markets. The share of guava in fresh fruit export from

ndia is merely 0.65% which can be further boosted, if fruit isroperly handled after harvest. Its delicate nature, short post har-est life and susceptibility to chilling injury and disease, limithe potential for commercialization of guava fruit (Goutam et al.,010). It is highly palatable and is one of the choicest fruits hav-

ng a rich source of vitamin C (260 mg/100 g pulp) (Pedapati et al.,014).

Guava, being a highly perishable fruit, undergoes rapid postarvest ripening in a few days under ambient conditions. Theyave high rates of respiration and thus a shorter shelf-life at room

∗ Corresponding author. Fax: +91 674 2562360.E-mail address: lalit.bal@gmail.com (L.M. Bal).

ttp://dx.doi.org/10.1016/j.scienta.2014.10.029304-4238/© 2014 Elsevier B.V. All rights reserved.

temperature due to various physiological factors regulated bygenetic mechanisms. The major changes taking place during itssenescence include loss in weight due to moisture loss, degradationof chlorophyll thus change in colour loss of turgidity and change intexture, loss of nutritional value and reduction in marketability.Loss of vitamin C after harvest takes place very fast which reducesits nutritive value unless appropriate post harvest measures aretaken. It is a climacteric fruit exhibiting respiratory and ethylenepeaks during ripening, it ripens rapidly after harvest and has shortshelf-life (Akamine and Goo, 1979; Brown and Wills, 1983; Bashirand Abu-Goukh, 2003). Therefore, guava cannot be sent to distantmarket under normal conditions. Storage of fruits at low tem-perature for a definite period is a common practice in developedcountries (Bhat, 2012).

Low temperature may delay or retard ripening and may reducespoilage. But the problem with guava fruit is its high chilling sensi-tivity (Wang, 1989) at very low temperature. Controlled/modifiedatmosphere (CA/MA) storage can extend the storage life ofmany tropical and subtropical fruit (Yahia, 1998). Although much

research has been done on the finding the optimal conditions forCA storage of most of horticultural commodities, guava is one ofthose commodities which has received less attention, despite itscommercial importance.

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N.R. Sahoo et al. / Scientia

Kader (2003) recommended 2–5% O2 and 0–1% CO2 for CA stor-ge of guava at 5–15 ◦C. Individual shrink wrapping (Pal et al., 2004),A storage (Singh and Pal, 2008) have also reported to be very effec-ive in maintaining quality of guavas. High moisture loss from theruits is the primary factor in deterioration of post-harvest qualityue to high water vapour deficit (Wu, 2010). The available infor-ation on the tolerance limits of guava fruit to low O2 and high

O2 atmosphere is sporadic and inconclusive.In recent days, apart from individual shrink wrapping, CA stor-

ge, surface coating etc., there also have been reports of differentethods of polymeric film packaging of fresh produces to increase

he shelf life. Those methods include MAP, MAP in ventilated films,acuum packaging, shrink packaging, cling film wrapping etc. Alsoeports says that polymeric film packaging in combination withool storage has been successful in delaying senescence, mainte-ance of physico-chemical constituents and extending shelf lifeRai and Paul, 2007). However, the selection of an appropriate pack-ging film and packaging techniques are the important criteria forts storage life.

Literature review revealed that no attempts have been made soar to uncover a suitable polymeric packaging material and tech-ique to extend the shelf life of highly perishable guava. Taking allhese into consideration, the present work has been undertaken tond out the most suitable packaging materials and technique tonhance storage life of guava and evaluation of physico-chemicalnd subjective quality during storage.

. Materials and methods

.1. Fruit material and sample preparation

Guavas of Allahabad Safeda variety were harvested manuallyrom Central Horticultural Experiment Station, Bhubaneswar as perhe standard maturity indices. Skin colour was considered to be theest indicator of harvest maturity of guava fruit (Mercado-Silvat al., 1998). Therefore, fruit having light green skin colour werearvested following commercial practice for long distance trans-ortation and storage. They were transported to the experimentite of food quality laboratory in plastic crates within 2–3 h of har-est. Manual sorting of fruits were done on the basis of size, freedomrom diseases and mechanical injuries. Only uniform sized matureruits with excellent organoleptic acceptability were selected forxperimental purpose. Fruits were washed with potable water andried under a fan, and then subjected to various storage conditionsithout any post-harvest fungicide treatment.

.2. Packaging conditions and storage

Six different packaging techniques used for packing approxi-ately 500 g of guava separately in each pack were MAP with LDPE,AP with PP, MAP in LDPE with pin holes films, MAP in PP with pin

oles films, shrink packaging with BOPP film, vacuum packagingith PP film.

LDPE film used for the MAP experiments was havinghickness 25 �, density 0.91 g/cc, oxygen transmission rate of400 cc(STP)/m2/day/bar, water vapour transmission rate of.5 g/m2/bar, tensile strength of 165 kg/cm2, elongation of 600%.P film used for the MAP, and vacuum packaging experimentsas having thickness 45 �, density 1.054 g/cc, oxygen transmis-

ion rate of 3000 cc(STP)/m2/day/bar, water vapour transmissionate of 7.75 g/m2/day/bar, tensile strength of 400 kg/cm2, elon-

ation of 300%. BOPP film used for shrink packaging experimentas having thickness 23 �, density 0.901 g/cc, oxygen transmission

ate of 4500 cc(STP)/m2/day/bar, water vapour transmission rate of8.0 g/m2/day/bar, tensile strength of 300 kg/cm2.

culturae 182 (2015) 1–7

Bag area of 10 × 10 cm2 was provided for each pack and perfo-rations provided in the LDPE and PP films were 5 holes of 0.3 mmdiameter in each side of the films. Similarly, a plastic tray contain-ing 500 g untreated fruits served as control. Both the control andthe treated fruits were kept as ambient condition (25–28 ◦C and60–70% R.H.) and in cool chamber (8–12 ◦C and 88–90% R.H.). Thetreatments were replicated six times comprising 500 g fruits perreplication. Periodical observations on various quality parametersof the fruits stored packages (in triplicate) were recorded as per theprocedure discussed below.

2.3. Evaluation of shelf life quality

2.3.1. Package headspace gas evaluationPackage headspace analysis for O2 and CO2 concentration was

carried out by a check point O2/CO2 instrument (PBI Dansensor,Denmark) at prespecified time of storage (Tirkey et al., 2014). Asmall self adhesive silicon septum is glued to the package and aneedle is pierced through this septum into the pack to draw thegas sample. The sensor signals is converted to concentration valuesof O2 and CO2, which are directly read on the digital display panelof the instrument. The accuracy of 0.1% for O2 and 2% for CO2 are infull range. The calibration for the instrument has been done withO2 and CO2 air percentages. Parameters were expressed as �CO2and �O2 percentage referred to initial values.

2.3.2. Physiological weight lossPhysiological loss in weight (PLW) was determined by weighing

all guava packages with a laboratory level weighing balance at thebeginning and end of the storage period. The difference betweenthe two values was considered as weight loss and expressed inpercentage (Sahoo et al., 2014).

PLW(%) = initial weight − final weightinitial weight

× 100

2.3.3. Ascorbic acid contentThe ascorbic acid of fruits were determined by the 2,6-

dichlorophenol indo phenol method (Ranganna, 2004). An aliquotof 10 ml juice extract was diluted to 50 ml with 3% meta-phosphoricacid in a 50 ml volumetric flask. The aliquot was then centrifugedfor 15 min and titrated with 2,6-dichlorophenol indo phenol dyeto a pink endpoint (persisting for 15 s). The ascorbic acid contentwas calculated from the titration value, dye factor, dilution and vol-ume of the sample and finally can be expressed as mg/100 g freshweight.

2.3.4. Fruit texture evaluationTexture Analyser (TA-XT Plus, Stable Microsystems Ltd., UK) was

used to measure the texture of the guava samples at regular inter-vals using an 8 mm stainless steel probe and 50 kg load cell. A stripof peel from the fruit was removed with the standard peeler pro-vided with the penetrometer. The probe was introduced into thefruit with gradual force without any jerk and the reading (kgf) wasrecorded. Readings at two different locations of each fruit was takenand at least 10 measurements were carried out for each packagingcondition and average data has been obtained.

2.3.5. Surface colour measurementHunter Lab colorimeter (ColourFlex, Hunter Associates Labora-

tory, Inc., VA, USA) was used to measure the surface colour of theguava samples equipped with a 12 mm measuring head (Bal et al.,

2011). Colour was measured using the CIE L, a, b scale and illu-minant D65. The instrument was calibrated with black and whitereference tiles through the tri-stimulus values X, Y and Z, tak-ing as standard values those of the white background (X = 79.01;

N.R. Sahoo et al. / Scientia Horticulturae 182 (2015) 1–7 3

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ig. 1. Changes in head space concentrations of O2 and CO2 under ambient condi-ion.

= 83.96; Z = 86.76) tile. The colour values were expressed as Lwhiteness or brightness/darkness), a (redness/greenness) and byellowness/blueness) at any time respectively. Since the guava didot cover the entire surface area, they were scanned at three dif-

erent locations to determine the average L, a and b values duringhe measurements. Numerical values of L, a and b were consideredor the evaluation of colour modification of the product. At eachtorage time, 10 measurements were carried out for each samplerom the packages.

.3.6. Subjective quality analysisFor assessing the marketable quality of the guava, descriptive

uality attributes were determined subjectively by observing theevel of visible mould growth, decay, shrivelling, smoothness andhine of the produce. The number of marketable vegetable exclud-ng decay after end of the storage period was used as a measure toalculate the percentage of marketable vegetable during storage.arketability of 80% and above was considered as the cut off point

or acceptance of the lot and was used as a benchmark for assess-ent of shelf life of the product (Mohammed et al., 1999; Tefera

t al., 2007).

.4. Statistical analyses

The results acquired were subjected to analysis of varianceANOVA) using SPSS 10.0 software. The means obtained from each

ig. 2. Changes in head space concentrations of O2 and CO2 under refrigeratedondition.

Fig. 3. Changes in physiological loss in weight under ambient storage.

set were compared using the Duncan’s multiple range test basedon a complete randomized design (at 0.05 confidence level).

3. Results and discussion

3.1. Head space gas

The in-pack gaseous concentrations of O2 and CO2 for guavastored in different packages under ambient and cold conditionswere shown in Figs. 1 and 2, respectively. After 2 days of storagein MAP under ambient condition, the in pack atmosphere arrivedat steady state stable level of 4.9(±0.34) and 4.8(±0.63)% O2 and2.3(±0.68), 2.7(±0.57)% of CO2 for the film packs with pin holesof LDPE and PP whereas the continuous film packs depicted anabrupt change in 1 day, a gradual change for next 2 days andthen almost equilibrated. The O2 level reduced from 22.0(±0.35)to 0.9(±0.02)% for LDPE and from 22.0(±0.35) to 0.7(±0.04)% forPP in 1 day and then remained almost constant at 0.2(±0.03)and 0.3(±0.05)% respectively from 3rd day onwards. CO2 levelincreased from an initial value of 0 to about 4.7(±0.31)% in LDPEand to 5.2(±0.19)% in PP in 1 day and then reduced gradually toattain a steady state of about 6.9(±0.34) % in LDPE and 7.3(±0.45)%in PP after 3 days of storage in ambient condition. Under coldcondition a similar trend was obtained but the changes were moregradual. Sahoo et al. (2014) made similar observation with storage

of bell pepper in polymeric films. In ambient storage of fruits invacuum pack and shrink pack, initially there was no head spacegas, however after 4 and 8 days of storage there was little gas

Fig. 4. Changes in physiological loss in weight under refrigerated storage.

4 N.R. Sahoo et al. / Scientia Horticulturae 182 (2015) 1–7

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ccumulation and the samples spoiled thereafter. So head spaceas analysis was not done for those samples. In case of cold storagef fruits, vacuum was maintained in both vacuum pack and shrinkack till 28 days of storage, so no head space gas analysis wasone.

.2. Physiological weight loss

The PLW of the guava fruits subjected to different packag-ng types and storage conditions were shown in Figs. 3 and 4.he PLW in case of guava was the maximum in the ambientontrol samples, where it was 5.05(±0.56)% in the 4th day oftorage as compared to 9.85(±1.13)% in 4th day in cold con-rol. The water loss above 5% is generally considered to cause aoticeable loss of quality and value (Kays, 1991). So the controlamples both under ambient and cold conditions were unmar-etable after 4 days of storage. Samples under ambient conditionf storage, PLW was observed to be 1.55(±0.37)% and 2.19(±0.53)%n MAP for PP and PP with pin holes stored samples respectively,

hereas slightly higher value of 5.14(±0.56)% PLW was recordedor shrink pack samples in 8 days storage. Under cold storage

here was no change in weight till 8th day in LDPE and PP storedamples. The PLW was 3.02(±0.81), 1.96(±0.54), 4.16(±0.58) and.74(±0.86)% in LDPE, PP, LDPE with pin holes and PP with pinoles packs, respectively at the end of 28th days of storage. But

able 1ffect of packaging material and storage environment on texture of guava.

Packaging material Firmness (kgf) in storage period (days)

0 4 8 12

AmbientControl 18.5a(0.42) 5.65b(0.35) 3.70c(0.37) –

LDPE 18.5a(0.42) 4.9b(0.51) 4.35bc(0.33) –

LDPE with pin holes 18.5a(0.42) 5.8b(0.18) 5.45bc(0.26) –

PP 18.5a(0.42) 8.55b(0.24) 6.51c(0.39) –

PP with pin holes 18.5a(0.42) 12.6b(0.68) 11.35c(0.22) –

Vacuum pack 18.5a(0.42) 13.5b(0.39) 11.75c(0.27) –

Shrink pack 18.5a(0.42) 7.45b(0.32) 5.85bc(0.46) –

ColdControl 18.5a(0.42) 5.15b(0.24) 4.95bc(0.33) 4.10c(LDPE 18.5a(0.42) 8.55b(0.34) 7.95c(0.42) 7.05d(LDPE with pin holes 18.5a(0.42) 9.20b(0.37) 8.35c(0.36) 7.35d(PP 18.5a(0.42) 13.85b(0.79) 13.54c(0.73) 11.93d(PP with pin holes 18.5a(0.42) 14.5b(0.83) 14.25c(0.35) 13.52d(Vacuum pack 18.5a(0.42) 14.50b(0.71) 13.68c(0.35) 13.53cd

Shrink pack 18.5a(0.42) 7.85b(0.31) 6.35c(0.35) 4.85d(

igures in parenthesis are standard deviation. Values in the same rows followed by differolyethylene, PP – polypropylene.

Fig. 6. Change in ascorbic acid content under refrigerated storage.

in case of cold shrink pack storage the PLW% was 5.26(±0.32)%at 16th day, which made it unmarketable. The higher PLW lossin shrink pack conditions might be due to the packaging materialbeing BOPP, which was having higher water vapour transmis-sion rate. The weight loss is a natural process of catabolism ofhorticultural products, catalyzed by enzymes. This decrease inweight may be attributed to respiration and other senescencerelated to metabolic processes during storage (Watada and Qi,1999).

3.3. Ascorbic acid content

The ascorbic acid content decreased with storage period underall the packaging treatments and storage environments. Howeverthe changes in ascorbic acid content during storage of guava weresignificantly higher in case of ambient storage as compared tocold storage conditions. The decrease in ascorbic acid during stor-age is due to conversion of ascorbic acid to dehydroascorbic aciddue to the action of ascorbic acid oxidase (Mapson, 1970; Singhet al., 2005). In the ambient control samples the decrease wasthe maximum (51.4%) from an initial value of 285.37(±2.35) to

138.74(±1.56) mg/100 g at the end of 8th day of storage (Fig. 5).Guava stored in LDPE with pin holes packs showed highest reten-tion (only 15.5% loss) of ascorbic acid (241.06(±2.59) mg/100 g)at the end of 8th day among the different packaging methods

16 20 24 28

– – – –– – – –– – – –– – – –– – –– – – –– – –

0.51) 3.75d(0.24) – – –0.26) 5.70e(0.42) 4.38f(0.72) 4.03g(0.25) 3.95gh(0.15)0.35) 6.90e(0.43) 6.37df(0.27) 6.16g(0.45) 5.95h(0.52)0.78) 9.85e(0.72) 8.76f(0.76) 8.32g(0.39) 6.83h(0.64)0.49) 13.46de(0.37) 12.08f(0.53) 11.95fg(0.61) 10.78h(0.38)(0.55) 13.17e(0.53) 12.89f(0.25) 12.76fg(0.83) 11.03h(0.67)0.26) 4.05e(0.37) 3.97ef(0.73) 3.32g(0.22) 3.06h(0.26)

ent superscript letters (a–h) are significant different (p < 0.05). LDPE – low density

N.R. Sahoo et al. / Scientia Horticulturae 182 (2015) 1–7 5

Table 2Effect of packaging material and storage environment on surface colour.

Packaging material Surface colour in storage period (days)

0 4 8 12 16 20 24 28

AmbientControlL 48.93 22.57 13.06a −7.94 −1.25 2.59b 8.23 19.92 32.92

LDPEL 48.93 35.64 23.04a −7.94 −3.81 −1.63b 8.23 14.69 21.23

LDPE with pin holesL 48.93 44.58 34.28a −7.94 −3.21 −2.26b 8.23 20.56 27.91

PPL 48.93 32.47 23.25a −7.94 −5.91 −6.21b 8.23 17.49 19.87

PP with pin holesL 48.93 33.39 24.20a −7.94 −0.87 −1.39b 8.23 14.54 23.38

Vacuum packL 48.93 32.53 26.17a −7.94 −5.68 −2.19b 8.23 11.54 17.08

Shrink packL 48.93 23.13 12.81a −7.94 −4.48 2.07b 8.23 12.42 25.29

ColdControlL 48.93 22.54 19.85 12.17a −7.94 −8.74 −9.31 −9.94b 8.23 11.32 13.09 19.48

LDPEL 48.93 35.67 31.42 29.57 29.49 27.81 27.90 29.08a −7.94 −8.85 −6.24 −5.56 −4.15 −4.97 −3.29 −3.17b 8.23 9.15 10.24 12.14 21.68 21.68 21.68 21.68

LDPE with pin holesL 48.93 33.54 31.35 28.71 27.53 21.71 19.34 18.04a −7.94 −8.52 −8.11 −6.03 −5.32 −4.68 −4.59 −3.26b 8.23 9.11 9.87 10.45 13.52 13.28 15.72 17.09

PPL 48.93 34.41 31.12 31.57 31.05 31.52 31.92 21.54a −7.94 −8.28 −8.01 −5.67 −5.68 −4.80 −4.63 −4.31b 8.23 13.65 15.14 18.71 15.56 16.50 16.64 17.27

PP with pin holesL 48.93 37.35 35.60 33.43 23.03 20.41 18.17 16.37a −7.94 −8.89 −7.53 −6.21 −5.67 −4.68 −4.30 −3.24b 8.23 13.81 14.45 15.63 12.53 14.83 14.69 15.59

Vacuum packL 48.93 35.12 31.83 29.94 25.41 23.77 23.49 21.40a −7.94 −8.63 −5.42 −5.06 −4.47 −5.14 −4.19 −5.38b 8.23 12.45 14.63 16.54 18.42 19.26 20.64 21.43Shrink packL 48.93 34.57 33.52 30.67 28.43 20.75 18.55 12.43

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a −7.94 −7.53 −5.52

b 8.23 11.06 15.44

nder ambient storage followed by the vacuum pack conditionhere the decrease (17.2%) was to 236.12(±2.68) mg/100 g. In cold

torage control samples the decrease of ascorbic acid was from85.37(±2.38) mg/100 g to 200.51(±1.97) mg/100 g at the end of6th day. Among cold storage condition, PP with pin holes showedhe best result (21% loss) with 225.30(±2.54) mg/100 g followed

−6.14 −6.55 −8.01 −8.70 −9.0518.67 20.09 21.51 21.47 22.02

by vacuum packaging (26% loss) with 211.15(±1.97) mg/100 gascorbic acid at the end of 28 days of storage (Fig. 6). The grad-

ual decline in ascorbic acid of the stored guava might be due toits decreased oxidation during storage. Nath et al. (2012) havereported similar studies for pear fruits using different packagingmaterials.

6 N.R. Sahoo et al. / Scientia Horticulturae 182 (2015) 1–7

Table 3Effect of packaging material and storage environment on the percent marketability of guava.

Packaging material Marketability (%) in storage period (days)

0 4 8 12 16 20 24 28

AmbientControl 100 76 26 – – – – –LDPE 100 75 37 – – – – –LDPE with pin holes 100 80 65 – – – – –PP 100 75 40 – – – – –PP with pin holes 100 82 71 – – – – –Vacuum pack 100 78 35 – – – – –Shrink pack 100 72 40 – – – – –

ColdControl 100 80 60 40 0 0 0 0LDPE 100 95 85 80 75 65 63 45LDPE with pin holes 100 85 75 65 58 55 45 30PP 100 100 95 90 85 70 65 60PP with pin holes 100 100 100 95 90 85 80 80Vacuum pack 100 100 95 90 90 85 80 75Shrink pack 100 100 85 80 80 75 70 65

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.4. Fruit firmness

Loss of firmness is one of the main factors limiting quality andhe post-harvest shelf-life of fruit and vegetables (Barth et al., 1993).

decrease in the peak force required to puncture the guava samplesas observed in all the packaging types both under ambient and

old storage conditions (Table 1). The decrease in peak force wasrom 18.5(±0.42) to 11.35(±0.22) kgf in PP with pin holes undermbient storage after 8 days of storage. The control sample showed

decrease of peak force from 18.5(±0.42) to 3.75(±0.24) kgf athe end of 16th day under cold storage. The decrease in punctureorce was gradual in all other samples stored in different packagingypes under cold condition. Samples stored in vacuum pack condi-ion maintained the best texture among all the cold stored samplesith a value of 11.03(±0.67) kgf at the 28th day. Sahoo et al. (2014)ade similar observation with storage of bell pepper in polymeric

lms. Gaspar et al. (1997) also reported that LDPE maintain thermness of guava fruits up to 2 days then PVC in turn maintain theuality.

.5. Colour values

The colour value ‘L’ represents the degree of lightness; ‘a’ valueepresents the degree of redness or greenness, whereas ‘b’ valueepresents the degree of yellowness or blueness. Lower value of ‘a’epresents more greenish colour of the fruit, which is due to theominance of chlorophyll pigments, whereas the positive valuef ‘b’ shows that the colour is changing towards yellow. In con-rol ambient sample there is a drastic colour change with ‘b’ valuehanging from an initial value of 8.23 to 32.92 in the 8th day indi-ating development of yellow colour very fast in ambient controlamples (Table 2). The same change was also confirmed from theisual observation of the ambient stored control samples whichere completely yellow at the end of 8th day of storage. The change

n ‘a’ value was gradual in ambient control and the change wasrom ‘−ve’ to ‘+ve’ at the end of 8th day indicating gradual changen colour from green towards reddish with the advancement oftorage period. This was also confirmed from the visual observa-ion of the samples and the colour change from green to reddish

rown spots which might be due to enzymatic action. In termsf colour retention, vacuum packaging followed by MAP with PPhowed better result over the other samples in the ambient storedruits.

In case of cold storage the change in ‘b’ value was gradual. Interms of ‘b’ value the guavas stored in PP with pin holes followedby LDPE with pin holes packaging condition retained better result.All the samples stored under cold storage retained greenness asindicated by −ve ‘a’ value in all the samples. However the samplesin MAP in PP with pin holes and MAP with LDPE showed betterresult over the others.

3.6. Fruit marketability

The percentage marketable guava obtained with duration ofstorage in different packaging materials and storage environmentwere shown in Table 3. The control guavas under ambient con-dition lost marketability very fast, it could not stay even up to 4days and at 8 days of storage the marketability reduced to unac-ceptable level of 26%. Slightly better results were obtained underambient storage with LDPE with pin holes and PP with pin holeswhere the marketability was reduced to 80 and 82% respectively in4 days of storage. All the ambient samples rapidly lost marketabil-ity in 8 days of storage. It is observed from Table 3, that the coldcondition could enhance the shelf life of samples in comparisonto ambient condition irrespective of the packaging type. Controlsamples could maintain the marketability of 80% up to 4 days ofstorage. The samples stored in LDPE, PP, PP with pin holes, vacuumand shrink pack remained marketable of 80%, 90%, 95%, 90% and 80%(more than 80%) up to 12 days of storage. Highest marketability ofguava of 80% was observed in PP with pin holes packs after 28 daysof storage. This shows guavas could be stored in good marketablecondition up to 28 days of storage in MAP with PP with pin holesfilms in cold condition. Srinivasa et al. (2006) found similar resultwith storage studies of tomato and bell pepper using eco-friendlyfilms. Jacomino et al. (2001) also reported the use of the low densitypolyethylene film with mineral incorporation (LDPEm) for pack-ing guavas was shown to be more efficient in maintaining the skincolour, pulp texture and overall quality. The good storage perfor-mance of fruits in terms of marketability in PP with pin holes in coldstorage could be attributed to the fact that low temperature stor-age along with modified atmosphere retarded the senescence dueto low respiration rate. The packs without any perforation showed

higher rotting percentage and water accumulation, which may bedue to anaerobic respiration. The performance of vacuum pack andshrink pack was significantly higher under cold condition than thatunder ambient condition.

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B

B

N.R. Sahoo et al. / Scientia

Though no significant biochemical changes could be observeduring the entire storage period, the marketability reduced rapidly

n some of the packaging material due to higher rotting percentage

.7. Post storage marketability

Guava fruits from the best two packaging and storage conditions.e., from PP with pin holes and vacuum pack with PP in cold storageondition were taken for post storage study after 20, 24 and 28 dayso simulate changes during super market retail conditions. Fruitsere removed from respective packaging films and were kept at

mbient condition (25–28 ◦C temperature and 60–70% R.H.). It wasound from the post storage study that, in the fruits from vacuumackage in PP after 24 days and PP with pin holes after 28 days ofold storage, PLW% increased, while TSS, ascorbic acid, fruit firm-ess, and percentage marketability decreased. The Hunter colouralues also changed rapidly making the fruits yellow within 3 daysf post storage.

. Conclusion

Overall, it is revealed that the in-pack guava created a suitableeadspace environment with low O2 and high CO2 concentrations,hich resulted in a better retention of freshness of the guava fruits

nd its marketability. Shrink packaging with BOPP film could notield better result under ambient storage because of high waterapour transmission rate of the film and consequently loss ofurgidity of the fruits. Among different packaging techniques andtorage conditions, MAP in PP with pin holes film in cold conditionas found to be the best followed by vacuum pack with PP film in

old condition and could be used to store for 28 days and 24 daysith maintenance of texture, colour, ascorbic acid and marketabil-

ty. During the post storage conditions guavas from above twoackaging and storage conditions could be held at ambient condi-ion for 3 more days after removal from packs. It is also inferred thatnder ambient conditions guava could be stored for 4 days usingDPE with pin holes and PP with pin holes as MAP storage. Commer-ialization of such innovations might bring large improvements inarketability and consumption of fresh guava. Furthermore, com-

ination of MAP systems with edible coatings (nanolaminates) cane a feasible way of improving microbial stability and quality ofresh guava, thus extending their shelf-life.

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