Original article

B. R. Doshi School Biosci.,Sardar Patel Univ., VallabhVidyanagar- 388 120, Gujarat,India,tadapanenirao@yahoo.com

Influence of zein and gelatin coatings on the postharvest quality and shelf life extension of mango (Mangifera indica L.) Neeta B. GOL, T.V. Ramana RAO*

* Correspondence and reprints

Received 20 February 2013Accepted 28 June 2013

Fruits, 2014, vol. 69, p. 101–115© 2014 Cirad/EDP SciencesAll rights reservedDOI: 10.1051/fruits/2014002www.fruits-journal.org

RESUMEN ESPAÑOL, p. 115

Influence of zein and gelatin coatings on the postharvest quality and shelflife extension of mango (Mangifera indica L.).Abstract – Introduction. Mango is the most economically important and nutritionally rich trop-ical fruit; it has high commercial value but a highly perishable nature; its sensitivity to postharvestdiseases and physical injury limits its successful marketing. Postharvest losses in fruits are a seri-ous problem because of rapid deterioration during handling, transport and storage. Edible filmsand coatings can be potentially used as an elective preservation technique to extend the shelf lifeof fruits. Materials and methods. The influence of zein and gelatin coatings on the physico-chemical characteristics, softening and antioxidative enzyme activities of mango fruits stored at(32 ± 1) °C were evaluated at regular intervals of their storage period and compared with mangowithout coatings (control). Results and discussion. Zein and gelatin coatings seemed to havea beneficial impact on delaying the changes in weight loss, soluble solids, titratable acidity, pH,sugar content and total carotenoids. Zein and gelatin coatings resulted in the highest retention ofascorbic acid and phenolic content as compared with that of control. Zein and gelatin coatingsdelayed the ripening of mango fruit by suppressing the activity of softening enzymes such aspolygalacturonase, pectin methyl esterase, cellulase and β-galactosidase. Zein 5% and gelatin10% coatings maintained the highest induction of defense-related peroxidase enzymes, followedby gelatin 5% and zein 10% coatings. Conclusion. The application of zein 5% and gelatin 10%coatings could be used in delaying the ripening, maintaining the quality attributes and extendingthe shelf life of mango fruit during storage.

India / Mangifera indica / fruits / keeping quality / edible films / zein / gelatin

Influence d’un enrobage de zéine et gélatine sur la qualité post-récolte etl’augmentation de la durée de vie de la mangue (Mangifera indica L.).Résumé – Introduction. La mangue est le fruit tropical le plus important sur le plan écono-mique et nutritionnel ; elle a une grande valeur commerciale mais est très périssable ; sa sensi-bilité aux maladies post-récoltes et aux blessures physiques limitent sa commercialisation. Lespertes post-récoltes des fruits sont un problème grave du fait de leur rapide détérioration aucours de la manutention, du transport et du stockage. Les films et revêtements comestibles peu-vent être utilisés potentiellement comme une technique de conservation pour prolonger la duréede vie des fruits. Matériel et méthodes. L’influence de revêtements à base de zéine et gélatinesur les caractéristiques physico-chimiques, le ramollissement et l’activité des enzymes antioxy-dantes de mangues stockées à (32 ± 1) °C a été évaluée à intervalles réguliers pendant leurpériode de stockage par rapport à des mangues non enrobées. Résultats et discussion. Lesrevêtements à base de zéine et gélatine ont semblé avoir un impact bénéfique pour retarderl’évolution de la perte de poids, des sucres solubles, de l’acidité titrable, du pH, des sucres etcaroténoïdes totaux. Les revêtements de zéine et gélatine ont permis une meilleure rétention desteneurs en acide ascorbique et composés phénoliques par rapport à celle du témoin. Les revê-tements à base de zéine et gélatine ont retardé le mûrissement des mangues en supprimant l’acti-vité des enzymes de ramollissement tels que la polygalacturonase, la pectine méthyle estérase, lacellulase et la β-galactosidase. Les revêtements à 5 % de zéine et à 10 % gélatine ont maintenula plus forte induction de l’enzyme peroxydase liée à la défense ; ils ont été suivis par les revê-tements à 5 % de gélatine et 10 % de zéine. Conclusion. Des revêtements à 5 % de zéine et 10 %de gélatine peuvent être appliqués pour retarder le mûrissement, maintenir les caractéristiques dequalité et prolonger la durée de conservation de la mangue pendant son stockage.

Inde / Mangifera indica / fruits / aptitude à la conservation / film comestible /zéine / gélatine

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1. Introduction

Mango (Mangifera indica L.) belongs to theAnacardiaceae family [1]; it is the secondmost frequently cultivated tropical fruitworldwide. Mango fruit is one of the mostimportant tropical fruits and it is known forits characteristic taste, aroma, flavor andhealth-promoting qualities, making it a com-mon ingredient in new functional foods of-ten labeled as “super fruits” [2]. Most of theworld’s mango production is consumed rawas a dessert fruit and the rest of it is processedinto diverse products such as puree, nectar,pickles, canned slices and chutneys [3].Mango is a climacteric fruit with a high com-mercial value but the domestic and interna-tional trade of fresh mango has been limitedby its highly perishable nature and its sen-sitivity to postharvest diseases and physicalinjury. The export of mango has becomehighly beneficial and, therefore, a longershelf life is necessary for its successful mar-keting and consumer satisfaction [4].

In tropical fruits postharvest losses are aserious problem because of rapid deterio-ration during handling, transport and stor-age [5]. In developing countries, postharvestwastage of mango fruit occurs due to poorstorage qualities and technologies. Severalviable technologies have been developed byresearchers for increasing the shelf life ofmangoes, which include low temperaturestorage, controlled atmosphere and modi-fied atmosphere or a combination of both [6].Mango fruits stored in a modified atmos-phere often show undesirable characteris-tics, i.e., poor color and poor eating quality,and the storage of mangoes below 10 °C re-sulted in chilling injury manifested in grayishscald-like discoloration of the skin, skin pit-ting, uneven ripening, reduction in the lev-els of carotenoids and aroma, and the pres-ence of undesirable flavors [2]. Therefore,there is a need to find alternative adequatepostharvest technologies for reducing post-harvest losses, thus extending the shelf lifeand maintaining the quality at low costs.These techniques should be simple, easilyavailable, environmentally friendly and rea-sonable, and have no known harmful effectson human health, hence the current interestin the formulation of edible coatings [7].

Edible films and coatings can be poten-tially used as an elective preservation tech-nique that can provide an additional protec-tive coating that can not only keep fruitplumpness, fresh appearance and hardnessbut also improve the luster of the fruit sur-face, thereby increasing the commercialvalue of fruits [8]. Currently the consumerinterest in biodegradable edible films orcoatings made from natural bio-based prod-ucts could be recognized as safe. Differentbiological materials such as polysaccha-rides, proteins and lipids have been used toprepare the coating material with the pur-pose of modifying the internal atmosphereof fruits and vegetables [9]. The use of ediblecoatings affords numerous advantages byavoiding the need for capital-intensive stor-age techniques. Protein-based coatingshave been made from some proteins whichinclude corn zein, wheat gluten, soy pro-tein, rice protein, egg albumin, milk proteinsand gelatin [10].

Zein is a natural storage protein found incorn kernels. Zein coatings have been usedto coat nuts and candy for increased gloss,prevention of oxidation and development ofoff-odors because of their good barrierproperties against oxygen and lipids [11].Zein coatings offer a reasonable alternativeto shellac and carnauba wax and that has re-ceived considerable attention in maintain-ing the overall fruit quality [11, 12]. Gelatin,an important biopolymer obtained by hy-drolysis from collagen, is widely used witha broad range of functional properties andapplications such as in the food, pharma-ceutical and photographic industries, in-cluding its film-forming ability. Gelatin filmsgenerally have effective barrier propertiesagainst oxygen and carbon dioxide [13].Aguilar-Mendez et al. found that the appli-cation of gelatin-starch coatings extendedthe postharvest shelf life of avocado [14].There is little information available aboutthe effect of protein-based edible coatingson extending the shelf life of fruits and veg-etables. Therefore, the objective of ourstudy was to assess the potential of zein andgelatin coatings on the extension of shelf lifeand postharvest quality retention of mangofruit.

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2. Materials and methods

2.1. Fruit material

Fresh mango (Mangifera indica L., cv.Kesar) fruits were harvested at their maturestage from an orchard located in the vicinityof Karamsad village in Anand district,Gujarat, India. The fruits were transportedto the research laboratory and they weregraded for their uniformity in size, shape andcolor, and fruit without any blemishes wereselected for the present study. The fruitswere sanitized in 2% sodium hypochloritesolution for 5 min, and then rinsed withwater and air-dried at room temperature.

2.2. Chemicals

Zein and gelatin were purchased fromHimedia (Mumbai, India). All other chemi-cals and solvents were of analytical gradeand obtained from Himedia, Merck and SRL(Mumbai, India).

2.3. Preparation of coatingformulations

Zein [5% and 10% (w/v)] coating solutionswere prepared by dissolving 5 g and 10 gof zein powder in 36.8 mL 95% alcohol,35 mL of 100% isopropanol and 28.2 mL ofdistilled water, and the solution washeated for 10–15 min at 75 °C on a mag-netic stirrer hotplate [11]. Glycerol monos-tearate (0.75%) was added as a plasticizerand the solution was stirred for 10 minunder the same magnetic stirring conditions(model: GENEI, SLM- HP- MS- 150). Gelatin[5% and 10% (w/v)] coatings were preparedby solubilizing 5 g and 10 g of gelatin pow-der in 100 mL of distilled water and con-stantly stirring on a magnetic stirrer hotplateat 70 °C for 30 min [15]. Glycerol monostea-rate (0.75%) was added as a plasticizer andthe solution was stirred for 10 min underthe same magnetic stirring conditions andsubsequently cooled at 40 °C.

2.4. Coating application

The fruit were randomly categorized intofive groups with seventeen fruits in each

treatment and each treatment was con-ducted with three replicates. Four groupswere categorized into one of the four coat-ing treatments (T): zein 5% (T1), zein 10%(T2), gelatin 5% (T3) and gelatin 10% (T4),while the fifth group contained untreatedfruit dipped in distilled water, designated ascontrol or uncoated (T5). The mango fruitwere subjected to the above-mentionedcoating solutions for 1 min. Residual solu-tions of fruit were allowed to drip off andthe fruit was dried at room temperature andstored at (32 ± 1) °C and 70–75% relativehumidity (RH). The coated and control fruitwere evaluated for quality attributes and theactivities of enzymes at the beginning of theexperiment (i.e., 0 days) and after (6, 12 and18) days of their storage period. For controlfruit the data were recorded only up to12 days of the storage period, as thereafterthey decayed completely.

2.5. Determination of weight loss

The mango samples (seven fruits per repli-cation) were weighed at the beginning ofthe experiment (i.e., 0 days) and at the endof each storage interval. The differencebetween the initial and final weight of thefruit was considered as a total weight lossand the results were expressed as the per-centage loss of the initial weight as per thestandard method of the AOAC [16].

2.6. Decay percentage

The decay percentage of coated anduncoated fruit was calculated as the numberof decayed fruit divided by the initialnumber of all fruit multiplied by 100.

2.7. Soluble solids, titratable acidityand pH

The soluble solids content of the fruit wasdetermined by using a hand refractometer(Atago Co., Tokyo, Japan). A sample wasprepared by mixing the fruit in a blender.The sample was thoroughly mixed, a fewdrops of the filtrate were placed on theprism glass of the refractometer and adirect reading was taken by reading the

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scale in the meter as described in the AOACmethod [16]. The titratable acidity wasdetermined according to the method ofMazumdar and Majumder by titration of5 mL of juice with 0.1 N sodium hydroxideusing phenolphthalein as an indicator, andthe results were expressed as the percent ofcitric acid [17]. The pH of the fruit sampleswas assessed using a digital pH meter(model: ELICO, LI 120) as per the standardmethod described by the AOAC [16].

2.8. Reducing sugars, non-reducingsugars and total sugars

Fruit pulp (0.5 g) was extracted with 5 mLof 80% ethanol for 5 min and refluxed for30 min. The sample was centrifuged at1000 × g for 30 min. The residue was againsubjected to ethanol extraction. The extractwas combined and the alcohol removed byevaporation. The remaining residue was dis-solved in 10 mL of distilled water. The aliq-uots (i.e., 0.2 mL to 0.5 mL) of the superna-tant were taken and the contents of reducingsugars (RS) and non-reducing sugars (NRS)were measured by following the dinitrosal-icylic acid (DNS) method, employing glu-cose as a standard [18], and the total sugarswere calculated as RS plus NRS.

2.9. Total phenols, ascorbic acidand total carotenoids

A fruit sample of (0.5 to 1) g was extractedwith 10 mL of 80% ethanol and the extractwas centrifuged at 10,000 rpm for 20 min.The clear supernatant was collected andallowed to evaporate at room temperature,and the remaining residue was dissolved ina known volume of distilled water. The aliq-uots (i.e., 0.2 mL to 2 mL) of the supernatantwere taken and total phenols were deter-mined as per the method of Bray andThorpe using Folin-Ciocalteu reagent [19].The standard calibration curve was pre-pared by using catechol at a concentrationof 0.1 mg⋅mL–1 in distilled water, whileascorbic acid was determined according tothe method of Roe [20], which is based onthe reduction of 2, 4-dichlorophenol indo-phenols by ascorbic acid. Levels of ascorbic

acid were estimated based on the standardcurve prepared from pure ascorbic acid. Thetotal carotenoid content was carried out asper the methods described by Wang et al.[21].

2.10. Extraction and assayof polygalacturonase (EC 3.2.1.15)and cellulase (EC 3.2.1.4)

Fruit tissue (2 g) was homogenized in 15 mLof sodium phosphate buffer (20 mM,pH 7.0) containing cysteine-HCl (20 mM),EDTA (20 mM) and Triton X-100 (0.05%).The homogenate was filtered and centri-fuged at 15,000 × g for 30 min at 4 °C in arefrigerated centrifuge (model: Eppendorf,5430R). The clear supernatant was used asenzyme extract for assaying polygalacturo-nase (PG) and cellulase enzyme activities[22]. For PG activity, the reaction mixturecomprised 0.2 mL sodium acetate (200 mM,pH 4.5), 0.1 mL NaCl (200 mM), 0.3 mLpolygalacturonic acid (PGA), 1% aqueoussolution adjusted to pH 4.5 and 0.1 mL ofenzyme extract in a total volume of 1.0 mL.The reaction mixture was held at 37 °C for1 h followed by addition of dinitrosalicylicacid. D-galacturonic acid was used as thestandard and one unit of enzyme activitywas defined as the amount of enzymerequired to liberate 1 nmol of galacturonicacid per min under the conditions of theenzyme assay [22]. For cellulose, the reac-tion mixture contained sodium acetatebuffer (100 mM, pH 5.0), carboxymethylcellulose (CMC) (1.5%) and enzyme in afinal volume of 1.0 mL. The cellulase activitywas assayed by measuring the reducinggroups released from CMC. One unit ofenzyme activity was the amount of enzymerequired to form 1 µmol of reducing groupsper hour, per gram of the original freshweight sample [22].

2.11. Extraction and assay of pectinmethyl esterase (EC 3.1.1.11)

The procedure for extraction and assay ofpectin methyl esterase (PME) was adaptedfrom Lohani et al. with some modifications[23]. The reaction mixture contained 1 mL

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pectin solution (0.01%, pH 7.5), 0.2 mLNaCl (0.15 M), 0.1 mL bromothymol bluesolution (0.01%), 0.2 mL water and 0.1 mLof enzyme extract. Absorbance was meas-ured immediately at 620 nm and againmeasured after 3 min. The difference in theinitial absorbance and absorbance after3 min was the measurement of PME activity.One unit of enzyme activity was defined asthe amount of enzyme required for liberat-ing 1 µmol of methyl ester⋅min–1.

2.12. Extraction and assayof β-galactosidase (EC 3.2.1.23)

The procedure for extraction and assay ofβ-galactosidase (β-gal) was followed inaccordance with Biswas [24]. The reactionmixture contained 0.25 mL of sodium ace-tate buffer (0.1 M, pH 5) and 0.01 mL of p-nitrophenyl β-D-galactopyranoside (PNPG)(10 mM) at 55 °C. The reaction was initiatedby adding 0.74 mL of enzyme extract andincubated for 10 min; similarly, the blankwas prepared without the enzyme extract,which is replaced by the buffer. The reactionwas terminated by adding 4 mL of NaOH(0.1 M) and the enzyme activity wasexpressed as µmol of p-nitrophenol (PNP)formed per minute per mg protein.

2.13. Enzyme extraction and assayof peroxidase (EC 1.11.1.7)

Peroxidase (POD) activity was assessedby following the method described byGuilbault [25]. The reaction mixture con-tained 10 µL of enzyme supernatant,2.99 mL H2O2 (0.03% in 0.01 M potassiumphosphate buffer, pH 6.0) and 0.05 mLorthodianisidine dye⋅6 mL–1of 0.03% ofH2O2 substrate solution (1% in methanol).The reaction mixture without substrateserved as a blank. The changes in absorb-ance were recorded at 460 nm for 1 min atthe interval of 15 s. Enzyme activity wasexpressed as the 1 unit change in opticaldensity per min per gram of fresh tissue.

2.14. Shelf life or marketable period

The shelf life of the coated and uncoatedmango fruit was calculated by counting the

days required for them to attain the last stageof ripening, but up to the stage when theystill remained acceptable for marketing [26].

2.15. Statistical analysis

The experiment was conducted in a com-pletely randomized design with three repli-cations. All the analyses performed werecarried out in triplicate and the standarddeviation was calculated. Data analyseswere performed by analysis of variance(ANOVA)using IRRISTATstatistical software(v. 3.1, IRRI, Manila, Philippines). Multiplecomparisons among the treatments with sig-nificant differences tested with ANOVAwere conducted by using the least signifi-cant difference (LSD) at the p < 0.05 level.Duncan’s multiple range test was used tocompare the mean values at different stor-age intervals [27].

3. Results and discussion

3.1. Weight loss

Water loss or transpiration is considered tobe the major factor that affects the storagelife and postharvest quality of the majorityof fruits. During our experiments, weightloss increased during the storage for allmango fruits, although a significantly (p <0.05) higher weight loss percentage wasnoted in the control fruit (figure 1). Theweight loss of the coated mango sampleswas lower as compared with the controlmango samples (figure 1). The fruits treatedwith zein and gelatin coatings presented alower weight loss throughout the entire stor-age period as compared with the uncoatedsamples. At the 12th day of the storageperiod, the weight loss in control mangofruit was highest (i.e., 22.34%); the lowestweight loss was noted in the gelatin 10%-and zein 5%-coated mango fruit, i.e., 6.03%and 6.72%, respectively. Among the cur-rently tested coatings, zein 5% and gelatin10% coatings showed a better effect ondelaying the weight loss of mango fruit atthe 18th day of storage. The postharvestwater loss can lead to wilting and shriveling,

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both of which reduce the marketability ofthe product [28]. Further, Hassani et al.stated that the weight loss reduction wasprobably due to the effect of a semi-perme-able barrier to gases and water vapor, there-fore reducing respiration, enzymatic brown-ing and water loss [28]. Our results are inagreement with those of Lim et al. [15],wherein gelatin-coated sweet cherry had alower level of water loss over the storageperiod. According to Cipolatti et al., theweight loss reduction can be due to theeffect of protein-based edible coatings,which prevented the dissection of the fruitsthat tend to have the walls degraded and thewater released, causing tissue wilting [12]. Asignificantly (p < 0.05) higher weight losswas observed in zein 10%-coated mangofruit as compared with that of zein 5% coat-ings, that could be due to the thickness ofthe coatings. The coating of zein 10% wasso thick that it covered the surface of thefruit; similar results were reported by Parket al., who reported that tomato fruit coatedwith a thick coating of corn zein resulted inO2 suppression at a very low level and CO2concentration at an excessive level, result-ing in the production of ethanol [29].

3.2. Decay percentage

Fruits and vegetables contain a wide rangeof organic substrates and high water activ-ity, and thus are good substrates for micro-bial infection [30]. The decay percentagewas significantly (p < 0.05) higher in the un-coated fruit, and fruit subjected to zein 10%and gelatin 10% coating treatments showeda moderate decay percentage (figure 1).Moreover, our results show that the fruitcoated with zein and gelatin coatings didnot show any decay percentage up to6 days of their storage period (figure 1).The initial decay percentage in uncoatedmango was 21.57%, and the incidence ofdecaying was increased and reached96.08% at the 18th day of the storage pe-riod. The coatings of zein 5% and gelatin10% significantly reduced the decay per-centage during the entire storage period incomparison with control and other coatingtreatments. The deterioration of fruits andvegetables during storage is mainly due tomoisture loss and wilting. The applicationof coating solution reduced the decay per-centage by providing a barrier which pro-tects fruits and vegetables against excessivetranspiration [31], and our results are sup-ported by the findings of Bai et al., whofound that ‘Gala’ apples coated with zeincoatings maintained their quality and re-duced the decay percentage as comparedwith the uncoated samples [11].

3.3. Concentration of soluble solids

The results of our study revealed that theconcentration of soluble solids (SS) inmango fruit increased during the storageperiod (figure 2). Treatment with the zeinand gelatin coatings reduced the increase inthe concentrations of SS. The increase in SSconcentration was extremely pronouncedin the control samples compared with thoseof coated samples. In control samples, thehighest SS concentration, i.e., 13.2 °Brix,was noted at the 6th day of the storageperiod; after that, it declined and reached12.3 °Brix at the 12th day of the storageperiod. All the coated samples showed a

Figure 1.Effect of zein and gelatincoatings on weight loss anddecay of coated and uncoated(control) mango during itsstorage (vertical bar representsmean ± standard deviation ofmeans for three replicates).

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gradual increment in SS concentration at theend of the storage period, except the zein10%-coated samples. The treatments of zein5% and gelatin 10% coating showed a ben-eficial effect on maintaining the SS accumu-lation at a slower level as compared withthe uncoated (control) and other coatingtreatments. During ripening the increase inthe SS content is due to starch hydrolysisand pectin degradation [12]. Sugars andorganic acids of the fruits are the main sub-strates consumed by respiration during stor-age. Edible coatings have a strong effect ondecreasing the metabolic processes, andfinally reducing the respiration rates [32].Our results are in accordance with those ofCipolatti et al., who found that protein-phe-nolic-based edible coatings retarded pectindegradation and fruit ripening in tomatofruit [12].

3.4. Changes in titratable acidityand pH

Titratable acidity (TA) of coated anduncoated mango fruit decreased markedlyduring the entire storage period (figure 2).The results of the present study revealedthat pH increased as TA decreased duringthe storage time. The TA of the coated man-goes decreased with the storage time but toa lesser extent than that of uncoated fruit.TA was significantly higher and pH was sig-nificantly lower in the zein- and gelatin-coated mango samples as compared withthose of uncoated samples (figure 2).Among the applied coatings, zein 5%, gela-tin 5% and gelatin 10% were the most effec-tive coatings in maintaining the TA at ahigher level and pH at a lower level as com-pared with control, while the zein 10% coat-ing also had a higher TA and lower pH butwith less evident results. At the 12th day ofstorage, the loss of TA in uncoated fruit wasaround 87% whilst TA in zein 5%-coatedmangoes decreased by 50%. With regard tothe coating treatments, gelatin 10% wasmore effective in retaining the TA at a higherlevel. As Echeverria and Valich reported thatTA is directly related to the concentration oforganic acids present in the fruits, the levelof TA declining during storage might be dueto the metabolic changes or to the use of

organic acid in the respiratory process [33].In this regard it is also considered that therate of respiration reduced by edible coat-ings may delay the utilization of organicacids present in the fruit [34]. Coatingslowed the changes in pH and TA in bananafruit by effectively delaying fruit senes-cence, as reported by Gol and Rao [35].Similar findings were obtained by Aguiaret al., who reported that mango fruit treatedwith galactomannan coating retained TA ata higher level as compared with uncoatedsamples [36].

3.5. Changes in reducing sugars,non-reducing sugars and totalsugars

Our results revealed that there was a signif-icant (p < 0.05) increase in the reducingsugar (RS), non-reducing sugar (NRS) and

FEctcm(sf

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igure 2.ffect of zein and gelatinoatings on soluble solids,itratable acidity and pH ofoated and uncoated (control)ango during its storage

vertical bar represents mean ±tandard deviation of meansor three replicates).

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total sugar (TS) contents of coated as wellas uncoated mango fruits during the storageperiod (figure 3). However, the rate ofincrease in RS, NRS and TS contents was sig-nificantly (p < 0.05) lower in coated samplesas compared with control samples. Themaximum amount of RS (38.66 mg⋅g–1),NRS (81.72 mg⋅g–1) and TS (120.39 mg⋅g–1)contents was noted in the control samplesat their 12th day of storage. The reducingsugar content was found to be higher inuncoated mango fruit, which might be dueto a decrease in the acidity as a result ofphysiological changes and rapid conversionof starch to sugars as a result of moistureloss, as previously reported by Wills andRigney [37]. In the case of coated samples,a significantly (p < 0.05) slower increase inRS, NRS and TS contents were noted withrespect to that of control, that might be dueto their slower ripening rate. This view con-curs with the results of Abbasi et al., who

studied the effect of chitosan coatings onpostharvest quality of mango fruit andobserved that the RS, NRS and TS contentswere less in the coated samples [38]. Amongthe tested coating treatments, zein 5% andgelatin 10% were the most effective in delay-ing RS, NRS and TS accumulation in mangofruit. These results are in agreement withthose of Li and Yu, who concluded that RScontent was significantly affected by coat-ings and/or films [39]. At the 18th day of thestorage period, mango fruit coated with gel-atin 10% showed a lower amount of RS, i.e.,25.21 mg⋅g–1, NRS, i.e., 88.04 mg⋅g–1 andTS, i.e., 113.25 mg⋅g–1 with respect to theother tested coatings. Maqbool et al. citedthat, during ripening, the fruit texture ischanged due to alteration in the cell wallstructure and the degradation of starch andresultantly bound carbohydrate fractions,especially pectic substances and hemicellu-loses [40]. The present results were similarto the results on ‘cat Hoa loc’ mangoeswhere the authors studied the effect ofdifferent coatings and observed that thecontents of RS and TS were lower in thecoated fruit with respect to those of controlfruits [41].

3.6. Changes in total phenolsand ascorbic acid

Total phenols and ascorbic acid contentdecreased with increasing storage time inboth coated and control samples (figure 4).The fruits coated with zein and gelatin coat-ings showed significant (p < 0.05) improve-ment in the retention of total phenols andascorbic acid with respect to that of controlfruit. Mango fruit treated with zein 5% andgelatin 10% had a higher content of totalphenols than either of the other coatingtreatments. All the coated fruit retained theirphenolic content up to the 18th day of theirstorage period but, among them, gelatin10% was superior in maintaining the totalphenol content at a higher level, i.e.,0.19 mg⋅g–1. Phenolics are considered asbiologically active components and widelydistributed in fruits and vegetables; theyhave the ability to scavenge free radicals,superoxide and hydroxyl radical by a singleelectron transfer [42]. Phenolic compounds

Figure 3.Effect of zein and gelatincoatings on reducing sugars,non-reducing sugars and totalsugars of coated and uncoated(control) mango during itsstorage (vertical bar representsmean ± standard deviation ofmeans for three replicates).

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have an important role in fruit quality main-tenance in terms of color, taste, aroma andflavor; in this regard, those coated fruit witha higher phenolic content would have ahigher quality than control fruit [43]. Theascorbic acid content of zein- and gelatin-coated mango samples was noted todecrease with time but to a lesser extentthan that of uncoated fruit. The maximumreduction in ascorbic acid values wasobserved in the control fruit (16.77 mg⋅100 g–1) at the 12th day of the storageperiod, while the least was noted in the zein-and gelatin-coated fruit. Ascorbic acid reten-tion was significantly affected by the zeinand gelatin coatings. Zein 5% and gelatin10% coating treatments showed a more pro-nounced effect in maintaining the ascorbicacid content at a higher level, i.e., 28.43 mg⋅100 g–1 and 29.26 mg⋅100 g–1, respectively,in comparison with other coatings. The lossof ascorbic acid can be greatly favored bythe presence of O2. The coating formula-tions may reduce O2 diffusion and that canbe attributed to a slow ripening rate, andconsequently better preservation of ascor-bic acid contents and delayed senescence[44]. Our results are consistent with those ofAbbasi et al. obtained in chitosan-coatedmango fruit [38].

3.7. Changes in total carotenoids

The carotenoid content gradually increasedduring storage in both coated and uncoatedmango fruit (figure 4). The highest increasein carotenoids was observed in uncoatedmangoes followed by zein 10%-coated fruit,while the mango fruit coated with zein 5%,gelatin 5% and gelatin 10% delayed theircarotenoid accumulation throughout thestorage. A significant (p < 0.05) increase incarotenoid content was observed at regularintervals in both coated as well as uncoatedmangoes. As the concentration of gelatin in-creased, the level of carotenoids decreased.Uncoated mango fruit showed their maxi-mum amount of carotenoids at the 12th dayof storage, while the coated mango samplesmaintained their carotenoid accumulationuntil the 18th day of storage, with a subse-quent increase in their accumulation. It ispossible that the coated fruits retained their

chlorophylls for a longer period, thereby re-ducing the carotenoid synthesis. In agree-ment with these findings, Ali et al. reportedthat coating application provided a barrieragainst gas exchange and production ofethylene, and therefore delayed the ripen-ing process [45]. Similar results were ob-served in the tomato fruit when treated withcorn zein coating and delayed the colorchange [46].

3.8. Activities of polygalacturonaseand pectin methyl esterase

Usually, tissue softening and the loss offirmness of fruit are mainly due to the deg-radation of cell wall components, e.g.,pectins, and destruction of the middlelamella structure [47]. Enzymes such aspolygalacturonase (PG), pectin methyl este-rase (PME), cellulase and β-galactosidase(β-gal) have been known to have active

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igure 4.ffect of zein and gelatinoatings on total phenols,scorbic acid and totalarotenoids of coated andncoated (control) mangouring its storage (vertical barepresents mean ± standardeviation of means for threeeplicates).

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roles in the softening of cell walls [47, 48].The results of our study showed that in bothcoated as well as control fruit, the activityof PG and PME enzymes increased signifi-cantly (p < 0.05) during their storage period,but the activity of these enzymes was lowerin the coated samples (figure 5). Controlmango fruit showed the greatest increase inPG activity during the entire storage periodand maximum activity, i.e., 0.15 units⋅mg–1

protein, was seen at the 12th day of the stor-age period, while the fruits treated with gel-atin 10% and zein 5% coatings exhibitedlower activities, i.e., 0.095 units⋅mg–1 pro-tein and 0.096 units⋅mg–1 protein, respec-tively. In this regard, Ruoyi et al. stated thatpartial inactivation of PG could result inreduced pectin solubilization and slowersoftening [49].

Pectin methyl esterase (PME) is alsoanother important enzyme involved in tex-tural changes [50]. In our experiments, thePME activity in control samples increasedand peaked at the 6th day of storage and

after that a gradual declining trend was seenin the activity (figure 5). At the 6th day ofstorage, the highest and lowest PME activi-ties were noted in the control and coatedsamples, respectively. Among the testedcoatings, the samples coated with zein 5%and gelatin 10% maintained their PME activ-ity at a lower level throughout the storageas compared with the zein 10% and gelatin5% coatings. Pectins, the main constituentsof the middle lamella and primary cell wallof the fruit, are hydrolyzed by PME to gen-erate demethylated pectins that can bemore easily hydrolyzed by PG, thus causingthe depolymerization of pectins [51, 52].The cell wall modifications result in loss ofwater, which is also considered as theimportant criterion for texture changes infruits and vegetables [14]. Edible coatingscreate a semipermeable barrier around thefruit, modifying the internal atmosphere byreducing O2 and/or elevating CO2 concen-trations. In view of this, Aguilar-Mendezet al. stated that low O2 and high CO2 con-centrations reduce the fruit enzymaticactivity, resulting in better firmness reten-tion of fruit [14]. Similar to our results,lower activities of polygalacturonase andpectinesterase are reported to contribute tothe enhanced retention of brittleness andfirmness during storage of shellac-coatedpears [51].

3.9. Activities of cellulaseand β-galactosidase

During ripening, cellulase plays an impor-tant role in fruit softening and it has a dif-ferent effect on softening changes indifferent fruits [51]. The cellulase and β-galactosidase (β-gal) activity in the zein-and gelatin-coated mango fruits was signif-icantly (p < 0.05) lower than that in thecontrol fruit during their storage period(figure 6). Maximum cellulase activity (i.e.,0.20 units⋅mg–1 protein) was noted at the6th day of the storage period and thereaftera decreasing trend was seen at the 12th dayof storage. Mango fruit treated with zeinand gelatin coatings maintained a constantincreasing behavior in the cellulase activity.Among the selected coatings, gelatin 10%and zein 5% were superior in inhibiting the

Figure 5.Effect of zein and gelatincoatings on polygalacturonaseand pectin methyl esterase ofcoated and uncoated (control)mango during its storage(vertical bar represents mean± standard deviation of meansfor three replicates).

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cellulase activity at a greater level. Theresults from our study are in agreementwith those of Zhou et al., where pear fruittreated with edible coating had lower cellu-lase activity as compared with that of con-trol fruit [51]. Our results showed theoverall response of β-gal activity in coatedas well as control mango fruit (figure 6).They indicated that β-gal activity washigher in the control samples throughoutthe storage period. Control fruit showed a73% increase in β-gal activity up to 12 daysof storage; however, a significant (p < 0.05)difference was observed among the coatingtreatments. Treatment with gelatin 10% andzein 5% coatings dramatically inhibited thisactivity at the end of the storage period andwas found to be effective in maintainingthe β-gal activity at a lower level. Theseresults were similar to those obtained inpapaya, in which the coating treatmentsinhibited the β-gal activity and maintainedit at a lower level [50].

3.10. Changes in peroxidase activity

Peroxidase (POD) is an important oxyrad-ical detoxification enzyme in plant tissue; itis considered to be associated with thedefensive system and may be related to themultiple changes affecting the texture, fla-vor and color of fruits and vegetables [53].In our experiments, the POD activity in allthe samples increased gradually, and theactivity was higher in the control sampleswith respect to that of coated samples (fig-ure 6). The POD activity in the control fruitincreased from 0 days to 6 days of storageand thereafter started to decline, while allthe coated samples showed a continuousincrement throughout the storage period,except the zein 10% coating. During the12 days of storage, the fruit coated with zeinand gelatin showed higher induction ofPOD activity and maintained it at the endof the storage period. Normally in plants theantioxidant enzyme activity is increased inresponse to stress, and a decrease in enzy-matic potential may be associated with areduction in the capacity to prevent damage[44]. In our study, coating treatment delayedthe senescence process of mango fruit byinducing higher POD activity, and theseresults were in correlation with those

obtained in pear fruit treated with shellaccoating which showed better membraneintegrity due to higher POD activity [51].

3.11. Shelf life or marketable period

The shelf life of mango fruit was extendedsignificantly (p < 0.05) with all the currentlytested edible coatings. During the storageperiod, the fruits treated with zein 5% andgelatin 10% coatings had a longer shelf life,i.e., 23 days, followed by gelatin 5% andzein 10% coatings, i.e., 21 days and 19 days,respectively. Uncoated mango fruit main-tained their shelf life up to only 14 days.Among the tested coating treatments, zein5% and gelatin 10% were effective and supe-rior in extending the mango shelf life for a

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igure 6.ffect of zein and gelatinoatings on cellulose,-galactosidase anderoxidase of coated andncoated (control) mangouring its storage (vertical barepresents mean ± standardeviation of means for threeeplicates).

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longer period. Similar results were observedin tomato fruit treated with zein coating andavocado fruit treated with gelatin-starchcoating [11, 14]. The positive effect of coat-ing on shelf life could be due to modifyingthe atmosphere (MA), and reducing mois-ture loss and surface wounding, as well asreducing a variety of diseases [11]. The MAcreated can delay the ripening process bydelaying ethylene production and reducingthe internal oxygen level, consequentlyextending the shelf life of fruits [54].

4. Conclusions

In conclusion, our study showed that thezein and gelatin coatings could delay theripening process of mango fruit. Changes inweight loss, soluble solids, titratable acidity,pH, total sugar content and total carotenoidswere positively affected by zein and gelatincoatings. In addition, the edible coatingsshowed a positive effect on keeping thetotal phenols and ascorbic acid at a higherlevel as compared with the control. Samplestreated with zein 5% and gelatin 10% coat-ings showed a lower percentage of thedecay rate. The application of zein 5% andgelatin 10% coatings also maintained thehigher induction of defense-related perox-idase enzyme and lower activities of soften-ing enzymes such as polygalacturonase,pectin methyl esterase, cellulase and β-galactosidase. In light of these results, theuse of zein 5% and gelatin 10% could be agood alternative in maintaining the qualityattributes and extending the shelf life ofmango fruit during storage.

Acknowledgments

Neeta B. Gol is grateful to the Council of Sci-entific and Industrial Research (CSIR), NewDelhi, for providing financial support underthe program of CSIR- SRF to carry out thiswork.

References

[1] Moalemiyan M., Ramaswamy H.S.,Maftoonazad N., Pectin-based edible

coating for shelf-life extension of ataulfomango, J. Food Process. Eng. 35 (2012)572–600.

[2] NiranjanaP.,GopalakrishnaR.K.P.,SudhakarR.D.V., Madhusudhan B., Effect of controlledatmosphere storage (cas) on antioxidantenzymes and Dpph- radical scavengingactivity of mango (Mangifera indica L.) cv.Alphonso, Afr. J. Food Agric. Nutr. Dev. 2(2009) 779–792.

[3] Bello-Perez L.A., Aparicio-Saguilan A.,Mendez-Montealvo G., Solorza-Feria J.,Flores-Huicochea E., Isolation and partialcharacterization of mango (Magnifera indicaL.) starch: morphological, physicochemicaland functional studies, Plant Foods Hum.Nutr. 60 (2005) 7–12.

[4] Anjum M.A., Ali H., Effect of various calciumsalts on ripening of mango fruits, J. Res. 15(2004) 45–52.

[5] Yahia E., Modified and controlled atmos-pheres for tropical fruits, Hortic. Rev. 22(1980) 123–183.

[6] Kader A.A., Prevention of ripening in fruits byuse of controlled atmosphere, Food Technol.34 (1980) 51–54.

[7] Tharanathan R.N., Kittur F.S., Chitin – Theundisputed biomolecule of great potential,Crit. Rev. Food Sci. Nutr. 43 (2003) 61–87.

[8] Xu S., Xu L.D., Chen X., Determining opti-mum edible films for kiwifruits using an ana-lytical hierarchy process, Comput. Oper.Res. 30 (2003) 877–886.

[9] Cisneros-Zevallos L., Krochta J.M., Wheyprotein coatings for fresh fruits and relativehumidity effects, J. Food Sci. 68 (2003) 176–181.

[10] Moldao-Martins M., Beirao-da-Costa S.M.,Beirao-da-Costa M.L., The effects of ediblecoatings on postharvest quality of the“Bravo de Esmolfe” apple, Eur. Food Res.Technol. 217 (2003) 325–328.

[11] Bai J., Alleyne V., Hagenmaier R.D., MattheisJ.P., Baldwin E.A., Formulation of zein coat-ings for apple (Malus domestica Borkh.),Postharvest Biol. Technol. 28 (2003) 259–268.

[12] Cipolatti E.P., Kupski L., Rocha M., OliveiraM.S., Buffon J.G., Furlong E.B., Applicationof protein-phenolic based coating on toma-toes (Lycopersicum esculentum), Ciênc. Tec-nol. Aliment. Campinas 32 (2012) 594–598.

[13] Jiang M., Liu S., Du X., Wang Y., Physicalproperties and internal microstructures of

Fruits, vol. 69 (2)

Coatings and shelf life extension of mango

films made from catfish skin gelatin andtriacetin mixtures, Food Hydrocoll. 24 (2010)105–110.

[14] Aguilar-Mendez M.A., Martin-Martinez E.S.,Tomas S.A., Cruz-Orea A., Jaime-FonsecaM.R., Gelatin-starch films: Physicochemicalproperties and their application in extendingthe post-harvest shelf life of avocado (Per-sea americana), J. Sci. Food Agric. 88 (2008)185–193.

[15] Lim R., Stathopoulos C.E., Golding J.B.,Effect of edible coatings on some qualitycharacteristics of sweet cherries, Int. FoodRes. J. 18 (2011) 1237–1241.

[16] Anon., Official methods of analysis, 16th ed.,Assoc. Off. Anal. Chem. (AOAC), Va., U.S.A.,1994.

[17] Mazumdar B.C., Majumder K., Methods onphysico-chemical analysis of fruits, DayaPubl. House, Delhi, India, 2003, pp. 93–139.

[18] Thimmaiah S.K., Standard methods of bio-chemical analysis, Kalyani Publ., New Delhi,India, 1999, pp. 51–59.

[19] Bray H.C., Thorpe W., Analysis of phenoliccompounds of interest in metabolism, Meth-ods Biochem. Anal. 1 (1954) 27–52.

[20] Roe J.H., Chemical determination of ascor-bic, dehydroascorbic acid and diketoglu-conic acids, in: Gluk D. (Ed.), Methods ofbiochemical analysis I, Interscience, NewYork, U.S.A., 1964, pp. 113–139.

[21] Wang Z.F., Ying T.J., Bao B.L., Huang X.D.,Characteristics of fruit ripening in tomatomutant epi, J. Zhejiang Univ. Sci. 6 (2005)502–507.

[22] Srivastava M.K., Dwivedi U.N., Delayed rip-ening of banana fruit by salicylic acid, PlantSci. 158 (2000) 87–96.

[23] Lohani S., Trivedi P.K., Nath P., Changes inactivities of cell wall hydrolases during ethyl-ene-induced ripening in banana: effect of 1-MCP, ABA and IAA, Postharvest Biol. Tech-nol. 3 (2004) 119–126.

[24] Biswas T.K., β-Galactosidase activity in thegerminating seeds of Vigna sinensis, Phyto-chem. 24 (1985) 2831–2833.

[25] Guilbault G.G., Handbook of enzymaticmethods of analysis, Marcel Dekker Inc.,New York, U.S.A., 1976, 147 p.

[26] Mondal M.F., Production and storage offruits (in Bangla), Mrs. Afia Mondal. BAUCampus, Mymensingh, Bangladesh, 2000,pp. 312.

[27] Bliss C.I., Statistical methods for research inthe natural sciences, Vol. 1, in: Statistics inbiology, McGraw Hill, New York, U.S.A.,1967, 558 p.

[28] Hassani F., Garousi F., Javanmard M., Ediblecoatings based on whey protein concen-trate- rice bran oil to maintain the physicaland chemical properties of the kiwi fruit(Actinidia delicosa), Trakia J. Sci. 10 (2012)26–34.

[29] Park J.H., Weller C.L., Vergano P.J., TestinR.F., Permeability and mechanical propertiesof cellulose-based edible films, J. Food Sci.58 (1993) 1361–1364.

[30] Chun-Ta W., An overview of postharvestbiology and technology of fruits and vegeta-bles, in: Proceedings of AARDO workshopon technology on reducing post-harvestlosses and maintaining quality of fruits andvegetables, Taiwan Agric. Res. Inst., Counc.Agric., Taichung, Taiwan, 2010, pp. 2–11.

[31] Chien P.J., Sheu F., Yang F.H., Effect ofedible chitosan coating on quality and shelflife of sliced mango fruit, J. Food Eng. 78(2007) 225–229.

[32] Zhou R., Mo Y., Li Y., Zhao Y., Zhang G., HuY., Quality and internal characteristics ofHuanghua pears (Pyrus pyrifolia Nakai, cv.Huanghua) treated with different kinds ofcoatings during storage, Postharvest Biol.Technol. 49 (2008) 171–179.

[33] Echeverria E., Valich J., Enzymes of sugarand metabolism in stored Valencia organs, J.Am. Soc. Hort. Sci. 114 (1989) 445–449.

[34] Yaman O., Bayoindirli L., Effects of an ediblecoating and cold storage on shelf-life andquality of cherries, LWT - Food Sci. Technol.35 (2001) 146–150.

[35] Gol N.B., Rao T.V.R., Banana fruit ripening asinfluenced by edible coatings, Int. J. FruitSci. 11 (2011) 119–135.

[36] Aguiar R.P., Miranda M.R.A., Lima A.M.P.,Mosca J.L., Moreira R.A., Eneas-Filho.,Effect of a galactomannan coating on mangopostharvest physicochemical quality param-eters and physiology, Fruits 66 (2011) 269–278.

[37] Wills R.B.G., Rigney C.J., Effect of calciumon activity of mitochondria and pecticenzymes isolated from tomato fruits, J. FoodBiochem. 3 (1980) 103–110.

[38] Abbasi N.A., Iqbal Z., Maqbool M., Hafiz I.A.,Postharvest quality of mango (Mangiferaindica L.) fruit as affected by chitosan coa-ting, Pak. J. Bot. 41 (2009) 343–357.

Fruits, vol. 69 (2

) 113

114

N.B. Gol and T.V.R. Rao

[39] Li H., Yu T., Effect of chitosan on incidence ofbrown rot, quality and physiologicalattributes of postharvest peach fruit, J. Sci.Food Agric. 81 (2000) 269–274.

[40] Maqbool M., Ali A., Alderson P.G., Zahid N.,Siddiqui Y., Effect of a novel edible compos-ite coating based on gum arabic and chi-tosan on biochemical and physiologicalresponses of banana fruit during cold stor-age, J. Agric. Food Chem. 59 (2011) 5474–5482.

[41] Hoa T.T., Ducamp M.N., Effects of differentcoatings on biochemical changes of ‘catHoa loc’ mangoes in storage, PostharvestBiol. Technol. 48 (2008) 150–152.

[42] Pila N., Gol N.B., Rao T.V.R., Effect of post-harvest treatments on physicochemical char-acteristics and shelf life of tomato (Lycoper-sicon esculentum Mill.) fruit during storage,Am.-Eur. J. Agric. Environ. Sci. 9 (2010) 470–479.

[43] Díaz-Mula H.M., Serrano M., Valero D., Algi-nate coatings preserve fruit quality and bio-active compounds during storage of sweetcherry fruit, Food Bioprocess Technol. 5(2012) 2990–2997.

[44] Xing Y., Li X., Xu Q., Yun J., Lu Y., Tang Y.,Effects of chitosan coating enriched withcinnamon oil on qualitative properties ofsweet pepper (Capsicum annuum L.), FoodChem. 124 (2011) 1443–1450.

[45] Ali A., Maqbool M., Ramachandran S.,Alderson P.G., Gum arabic as a novel ediblecoating for enhancing shelf-life and improv-ing postharvest quality of tomato (Solanumlycopersicum L.) fruit, Postharvest Biol.Technol. 58 (2010) 42–47.

[46] Park H.J., Chinnan M.S., Shewfelt R.L., Edi-ble coating effects on storage life and qualityof tomatoes, J. Food Sci. 59 (1994) 568–570.

[47] Lefever G., Vieuille M., Delage N., D’HarlingueA., Monteclerc J.D., Bompeix G., Character-ization of cell wall enzyme activities, pectin

composition and technological criteria ofstrawberry cultivars (Fragaria × ananassaDuch), Food Chem. Toxicol. 69 (2004) 221–226.

[48] PatelP.R.,GolN.B.,RaoT.V.R.,Physiochem-ical changes in sunberry (Physalis minima L.)fruit during growth and ripening, Fruits 66(2011) 1–10.

[49] Ruoyi K., Zhifang Y., Zhaoxin L., Effect ofcoating and intermittent warming on en-zymes, soluble pectin substances and ascor-bic acid of Prunus persica (cv. Zhonghuash-outao) during refrigerated storage, Food Res.Int. 38 (2005) 331–336.

[50] Gonzalez-Aguilar G.A., Valenzuela-Soto E.,Lizardi-Mendoza J., Goycoolea F., Martinez-Tellez M.A., Villegas-Ochoa M.A., Monroy-Garcia I., Ayala-Zavala J.F., Effect of chi-tosan coating in preventing deterioration andpreserving the quality of fresh-cut papaya‘Maradol’, J. Sci. Food Agric. 89 (2009) 15–23.

[51] Zhou R., Li Y., Yan L., Xie J., Effect of ediblecoatings on enzymes, cell membrane integ-rity, and cell-wall constituents in relation tobrittleness and firmness of Huanghua pears(Pyrus pyrifolia Nakai, cv. Huanghua) duringstorage, Food Chem. 124 (2011) 569–575.

[52] Rao T.V.R., Gol N.B., Shah K.K., Effect ofpostharvest treatments and storage temper-atures on the quality and shelf life of sweetpepper (Capsicum annum L.), Sci. Hortic.132 (2011) 18–26.

[53] Oms-Oliu G., Odriozola-Serrano I., Soliva-Fortuny R., Martin-Belloso O., The role ofperoxidase on the antioxidant potential offresh-cut ‘Piel de Sapo’ melon packagedunder different modified atmospheres, FoodChem. 106 (2008) 1085–1092.

[54] El Ghaouth A., Ponnampalam R., CastigneF., Arul J., Chitosan coating to extend thestorage life of tomatoes, HortSci. 27 (1992)1016–1018.

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Influencia de un revestimiento de zeína y gelatina en la calidad postcosechay en el aumento de la duración de vida del mango (Mangifera indica L.).

Resumen – Introducción. El mango es el fruto tropical más importante en el plano económicoy nutricional; posee un gran valor comercial, pero es muy perecedero. Su sensibilidad frente alas enfermedades postcosecha y a los daños físicos limita su comercialización. Las pérdidaspostcosecha de los frutos son un grave problema, dado su rápido deterioro durante la manuten-ción, el transporte y el almacenamiento. Las películas de envasado y los revestimientos comes-tibles pueden emplearse potencialmente como una técnica de conservación para prolongar laduración de vida de los frutos. Material y métodos. Se evaluó, en intervalos regulares, duranteel periodo de su almacenamiento, la influencia de revestimientos a base de zeína y gelatina enlas características físico-químicas, en el reblandecimiento y en la actividad de las enzimasantioxidantes de mangos almacenados a (32 ± 1) °C, en relación con los mangos no revestidos.Resultados y discusión. Los revestimientos a base de zeína y gelatina parecieron tener unimpacto benéfico en el retraso de la evolución de la pérdida de peso, de los azúcares solubles,de la acidez valorable, del pH, de los azúcares y carotenoides totales. Los revestimientos dezeína y gelatina dieron lugar a una mejor retención de contenidos de ácido ascórbico y com-puestos fenólicos, en relación con la del testigo. Los revestimientos a base de zeína y gelatinaatrasaron la maduración de los mangos mediante supresión de la actividad de las enzimas dereblandecimiento, tales como la poligalacturonasa, la pectina metil esterasa, la celulasa y la β-galactosidasa. Los revestimientos del 5 % de zeína y del 10 % de gelatina mantuvieron la mayorinducción de la enzima peroxidasa ligada a la defensa; les siguieron los revestimientos del 5 %de gelatina y del 10 % de zeína. Conclusión. Los revestimientos del 5 % de zeína y del 10 % degelatina pueden aplicarse para atrasar la maduración, mantener las características de calidad yprolongar la duración de conservación del mango durante su almacenamiento.

India / Mangifera indica / frutas / aptitud para la conservación / film comestible /zeina / gelatina

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