gelatin-based edible coating combined with mentha pulegium...

Research ArticleGelatin-Based Edible Coating Combined with Mentha pulegiumEssential Oil as Bioactive Packaging for Strawberries

Mohamed Aitboulahsen 1 Said Zantar2 Amin Laglaoui3 Hicham Chairi1

Abdelhay Arakrak3 Mohammed Bakkali3 and Mounir Hassani Zerrouk 1

1Department of Biology Polydisciplinary Faculty of Larache Abdelmalek Essaadi University BP 745 Larache Morocco2Department of Biology Faculty of Science and Technology Abdelmalek Essaadi University BP 416 Tangier Morocco3Research Unit of Nuclear Technology Environment and Quality National Institute of Agronomic Research90010 Tangier Morocco

Correspondence should be addressed to Mounir Hassani Zerrouk mounirtechyahooes

Received 8 May 2018 Accepted 11 June 2018 Published 4 July 2018

Academic Editor Francisca Hernandez

Copyright copy 2018 Mohamed Aitboulahsen et al is is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium provided the original work isproperly cited

e eect of gelatin-based edible coating incorporated with Mentha pulegium essential oil (MEO) on physicochemical (pHtitratable acidity (TA) weight loss total soluble solids (TSS) and total phenolic content (TPC)) microbiological (total aerobicmesophilic ora (TAMF) and yeasts and moulds (YM)) and sensorial (color and rmness) characteristics of strawberries storedunder refrigeration was studied Strawberries were coated with gelatin alone (4) andor gelatin combined with two con-centrations (05 and 1) of MEO and stored at 4degC for 13 days Gelatin coating andMEO combination signicantly inhibited totalora and moulds and yeasts with comparison to control (uncoated strawberries) and had better hygienic quality at the end ofstorage e eect wasMEO concentration dependent Our results also showed that the bioactive coating used in this investigationslowed down changes in pH TA weight loss TSS rmness TPC and color of strawberries Gelatin coating incorporated withMEO at 1 protected at least 60 of strawberries from deterioration after 13 days of storage and could be used as bioactivepackaging to prolong the shelf life and an alternative of pesticides use

1 Introduction

eMoroccan agricultural sector contributes around 12 ofGDP and remains until today the largest employmentprovider in the country [1] Loukkos and Gharb (Northwestof Morocco) are the most important agricultural regionsRed berries occupy the rst place of cultivated productsproviding 169000 tons in 2017 [2]

Strawberries (Fragaria) are perennial plants belonging tothe Rosaceae family ey are rich in antioxidants poly-phenols and other benecial nutrients [3] Howeverstrawberries are perishable and maintaining their freshnessand quality after harvest is mostly related to the handlingtransport and storage methods that are used [4]

Most of the postharvest fruits and vegetables losses arecaused by fungal and bacterial diseases Botrytis cinerea is

a serious problem for strawberry growers e disease candevelop during storage if the fruit has been contaminatedduring harvesting or handling [5] Also Rhizopus soft rotcaused by Rhizopus stolonifer can be problematic in smallfruits Cooling and fruit preservation by chemicals likefungicides are traditional techniques that could reduce theincidence of these fungi However the problem of resistancedevelopment in microbial strains questions their eective-ness especially when the regulation is stricter

e use of biopolymers-based edible coatings for foodpreservation has been largely used in the last decades toimprove the shelf life of fruits and preserve their freshness[6] Edible coatings can be dened as a thin layer of ediblematerial that coats the food and limits the migration of watervapor oxygen and CO2 among others [7] Biopolymersusually applied for food preservation can be of dierent

HindawiJournal of Food QualityVolume 2018 Article ID 8408915 7 pageshttpsdoiorg10115520188408915

natures like protein lipids and polysaccharides )echemical and physical characteristics of the biopolymer useddetermine their efficacy to be used for food shelf life pro-longation )ese coatings can also become bioactive by theincorporation of biomolecules with antimicrobial and an-tioxidant properties

Essential oils have been largely used to preserve thequality of food due to their antimicrobial and antioxidantactivities [8ndash13] MEO is considered as one of the mosteffective essential oils against a large spectrum of bacterialand fungal strains [14 15] Several biopolymers-basedcoating incorporated with EOs have been used for straw-berries preservation [16 17] Due to their mechanical re-sistance barrier properties and sensorial acceptabilitygelatin has been largely used to prolong the shelf life of foodssuch as meat and fish [18ndash20] However to the best of ourknowledge the effect of gelatin coating on strawberrypreservation is limited and has been used in only a fewstudies [21]

In this sense our work aims at evaluating the combinedeffect of gelatin-based coating and MEO on physicochem-ical microbiological and sensorial characteristics ofstrawberries during storage under refrigeration

2 Materials and Methods

21 Raw Material Fresh strawberries (Sabrina) were col-lected from the experimental center of the National Instituteof Agronomic Research (Larache Morocco) during theseason of 2018 )ey were transported to the laboratoryNoninjured fruit were sorted for their uniformity in sizefirmness and color

22 Essential Oil Isolation Essential oil used in this in-vestigation was obtained by hydrodistillation from plants ofM pulegium collected in the northeastern part of Morocco(Oujda) )e taxonomic identities of the plants were con-firmed by comparing voucher specimens with those ofknown identity previously deposited in the National Her-barium of the Scientific Institute of Rabat

23 Gelatin Coating Formation Twelve grams of gelatinpowder (HiMedia Laboratories Pvt Ltd India) was dis-solved in 300mL of sterile distilled water and stirred at 45degCfor 10min Sorbitol (Loba Chemie Pvt Ltd India) (ww ofgelatin) was added to increase mixture stability 15 and 3mLof MEO were added to prepare bioactive gelatin coating at05 and 1 respectively TWEENreg 80 was used as anemulsifier

After mixture homogenization washed strawberrieswere dipped into the prepared solution for about 90 secondsthey were filtered thereafter using a filter funnel and resetinto labeled plastic punnets Four treatments were prepared

T1 control (uncoated strawberries)T2 gelatin coating without MEOT3 gelatin coating with 05 MEOT4 gelatin coating with 1 MEO

)e punnets were packed with a plastic wrap and storedin at 4degC )e physicochemical microbiological and sen-sorial parameters were tested on the first day and after 3 710 and 13 days

24 Microbiological Parameters )e count of total aerobicmesophilic flora (TAMF) and yeasts and moulds (YM) wereperformed according to Jay et al [22] after 0 3 7 and 10days of storage

25 Physicochemical and Sensorial Parameters pH totalsoluble solids (TSS) and titratable acidity (TA) were mea-sured as described in official methods of analysis [23]

)e maturity index (MI) was calculated as the ratio ofTSS and TA Fruit firmness was measured using a TA1texture analyzer (Ametek Lloyd Instruments Ltd UK) bysetting crosshead speed at 1mms and penetration depth at10mm Firmness expressed in N is the textural parametermeasured on the resulting force-distance curve

Fruit color was measured using CR-300 Chroma Meter(Konica Minolta CR-300 Osaka Japan) and Llowast (lightness)alowast (redness) and blowast (yellowness) values were obtained )echroma value C was calculated using the following equation

C a2

+ b2

1113872 111387312

(1)

)e difference between the initial and final weight wasconsidered as the total weight loss Strawberry samples wereweighed at the beginning (ie 0 days) and at the end of eachstorage interval )e results were expressed as weight losspercentage Total phenolic content (TPC) was determinedusing the FolinndashCiocalteau reagent (Solvachim LaboratoiresCasablanca) according to the method described by Sir-iwoharn et al [24] using gallic acid (Loba Chemie Pvt LtdIndia) as standard )e calibration curve was plotted bymixing 05mL of 10 50 100 200 and 400 ppm gallic acidsolution with 75mL of distilled water and 05mL of theFolinndashCiocalteau reagent 05mL of the strawberry samplewas added to 75mL of distilled water and 05mL of theFolinndashCiocalteau reagent 05mL of distilled water was usedfor blank preparation Afterwards all tubes were mixed witha vortex and held for 10min at room temperature )en3mL of sodium carbonate (20) solution was added to eachtest tube Tubes were stirred and placed in a water bath at40degC for 20min and then cooled directly in an ice bath for3min )e absorbance of all samples was measured usinga 755 nm UV spectrophotometer (JP Selecta SA Spain)TPC was expressed in mg gallic acid equivalent (GAE)g dryweight

Visual decay was determined by a visual inspection at 03 7 10 and 13 storage days and was estimated as thenumber of infected fruits divided by the total number offruits expressed in percentage ()

26 Statistical Analysis All measurements were done intriplicates Data analyses were performed by one-wayanalysis of variance (ANOVA) followed by Tukeyrsquos posthoc tests to evaluate significant differences among the

2 Journal of Food Quality

samples at 95 confidence interval using SPSS computerprogram version 20 0)e level of significance was ple 005

3 Results and Discussion

31 Microbiological Characteristics of Control and Gelatinandor Gelatin +MEO Coated Strawberries )e effect ofgelatin andor gelatin +MEO coating at two concentrations(05 and 1) on the evolution of TAMF and YM duringstorage at 4degC is shown in Figures 1(a) and 1(b)

Initial microbial load of fresh strawberries in this studywas 23 logmiddotUFCg and 22 logmiddotUFCg for TAMF and YMrespectively Our values are similar to those obtained byShahbazi [25] Microbial load was increased significantly(ple 005) with increasing storage time in all treatmentsGelatin coating alone (T2) retarded slowly (lt07 logmiddotUFCg)themicrobial growth after 10 days of storage Gelatin coatingincorporated with MEO (1) (T4) delayed significantly(ple 005) the microbial growth by 174 logmiddotUFCg and082 logmiddotUFCg for TAMF and YM respectively after 10days At the end of storage TAMF and YMwere in the orderof 363 and 389 log CFUg respectively for gelatin +MEO(1) (T4) coated strawberries which is under the limit ofacceptance established for the shelf life of fruit-basedproducts [26] and indicate a good hygienic quality of thefruits after 10 days of storage )e inhibition magnitude wasEO concentration dependent)is is due to antibacterial andantifungal activities of the MEO largely demonstrated[15 27] Similar behavior was observed by Raquel et al [28]

who found that YM and psychrophils flora decrease fol-lowing the application of antimicrobial coating Shahbazi[25] also showed that the use of chitosan coating withMentha spicata EO was significantly effective against totalbacteria YM and extend the shelf life of fresh strawberries atleast up to 12 days In our case the antimicrobial activity ofM pulegium may be attributed to the oxygenated mono-terpenes such as pulegone and piperitone generally found inM pulegium EOs [15]

32 Physicochemical and Sensorial Characteristics of Controland Gelatin andor Gelatin +MEO Coated Strawberries

321 pH Titratable Acidity (TA) Total Soluble Solids (TSS)and Maturity Index (MI) Variations of pH TA TSS andMI during storage at 4degC are shown in Table 1 TA and TSScontent decreased while pH increased significantly(ple 005) during the storage period for all treatmentsGelatin +MEO (1) (T4) coating showed the lowest increasein pH (398) after 13 days which indicates that the use of thiscoating slows down changes in pH values

Table 1 shows also that gelatin-based coating (T2 T3and T4) reduced considerably the decrease of TA after 13days of storage in comparison with the control (T1) Ourresults are similar to those obtained by Shin et al andPetriccione et al [29 30] who reported that TA decreasedwith increasing storage period of strawberries )e sameauthors studying the effect of chitosan coating on straw-berries have noticed that TA decrease was more pronounced

0

1

2

3

4

5

6

0 3 7 10

Tota

l flor

a cou

nt (l

og C

FUg

)

Storage time (days)

ControlGelatin + MEO 05

Gelatin onlyGelatin + MEO 1

(a)

0

1

2

3

4

5

6

0 3 7 10Ye

asts

and

mou

lds c

ount

(log

CFU

g)

Storage time (days)

Control Gelatin onlyGelatin + MEO 05 Gelatin + MEO 1

(b)

Figure 1 Total aerobic mesophilic flora (TAMF) (a) and yeast and mould (YM) (b) counts of coated and uncoated strawberries duringstorage at 4degC for 10 days Vertical bars represent the standard deviation (n 3)

Journal of Food Quality 3

in uncoated samples (control) Previous studies have sug-gested that the higher acidity loss in uncoated fruits is dueto the use of organic acids as substrates for respiratorymetabolism during storage [31] In this sense Gol et al [16]reported that coatings can slow down respiration rate andmay therefore reduce the use of organic acids which leads tothe retention of TA in coated fruits

)e decrease of TSS content in gelatin +MEO (1)coating (T4) was delayed significantly (ple 005) in com-parison to the control (T1) at the end of storage (day 13) Ourresults agree with those obtained by Amal et al [32] whoreported that incorporation of thymol EO in soy protein orgluten films was themost effective treatments inmaintainingTSS during storage and concluded that the application ofcoatings on the surface of the strawberry reduced respirationrate hence reducing the loss of TSS Finally MI calculated asTSSTA ratio the most important parameter for evaluatingstrawberries quality shows that uncoated strawberries (T1)exhibited a significant bigger increase (ple 005) withcomparison to the coated ones (T2 T3 and T4) reflectingreduced ripening compared to uncoated strawberries

322 Weight Loss and Total Phenolic Content Figures 2and 3 show the effect of gelatin andor gelatin +MEOcoating at 05 and 1 on the weight loss and TPC ofstrawberries during the storage at 4degC respectively

Weight loss increased throughout the storage period forthe control (T1) and gelatin coated (T2 T3 and T4)strawberries with significant differences (ple 005) Un-coated fruits (T1) had the highest weight loss (24) after13 days while gelatin +MEO (1) (T4) had the lowestpercentage of weight loss (3) being under the limit forstrawberries acceptance (6) (Figure 2) Gelatin alone (T2)also reduces weight loss but not as effective as gelatin +MEO(1) (T4) treatment Our results are in accordance with

Wang et al [33] demonstrating that coatings reduce respi-ration rate and water loss Fakhouri et al and Poverenov et al[21 34] report that among the substances used to coat andprolong the shelf life of fruits gelatin is a feasible alternative toavoid the productrsquos weight loss after harvest )e evolution ofTPC in all treatments is summarized in Figure 3

Total phenolic content (TPC) obtained in this study arein the range of those obtained by Hoda et al [35] but su-perior of Li et al [36] (80mg100 g) Anttonen et al [37]reported that TPC varies according tomany parameters suchas variety level of fertilization or date of planting Figure 3shows also that TPC tends to decrease through the storage

Table 1 pH total soluble solids (TSS) titratable acidity (TA) and maturity index (MI) of coated and uncoated strawberries during storageat 4degC for 13 days

Storage time (days) 0 3 7 10 13

pH

T1 380plusmn 004Aa 389plusmn 002Ab 393plusmn 001Ab 419plusmn 001Ac 408plusmn 002AdT2 363plusmn 003Ba 372plusmn 007Ba 409plusmn 001Bbc 413plusmn 001Bb 401plusmn 001BcT3 376plusmn 002Aa 380plusmn 015ABb 384plusmn 001Cb 397plusmn 001Cc 403plusmn 002BdT4 362plusmn 002Ba 376plusmn 002Bb 379plusmn 001Db 388plusmn 001Dc 398plusmn 001Cd

TSS (brix)

T1 853plusmn 015Aa 747plusmn 025Ab 663plusmn 015ABc 517plusmn 012Ad 497plusmn 012AdT2 803plusmn 015ABb 683plusmn 006Bb 680plusmn 017Ab 520plusmn 010Ac 530plusmn 017AcT3 833plusmn 015Ba 643plusmn 012Cb 637plusmn 006Bb 553plusmn 058Bc 507plusmn 011AdT4 796plusmn 015Ba 677plusmn 006BCb 657plusmn 006ABbc 647plusmn 012Cc 610plusmn 010Bd

TA ()

T1 057plusmn 002ABa 045plusmn 001Ab 025plusmn 002Acd 022plusmn 001Ac 027plusmn 001AdT2 053plusmn 001Aa 047plusmn 002Ab 031plusmn 001Bc 023plusmn 001Ad 037plusmn 001BeT3 058plusmn 001Ba 039plusmn 003Bb 040plusmn 001Cb 034plusmn 002Bc 031plusmn 001CcT4 056plusmn 001ABa 049plusmn 001Ab 047plusmn 001Dbc 044plusmn 001Cc 037plusmn 002Bd

Maturity index ()

T1 1493plusmn 029Aa 1651plusmn 022Aad 2693plusmn 248Ab 2329plusmn 025Ac 1849plusmn 056AdT2 1507plusmn 054Aa 1445plusmn 082ABa 2183plusmn 054Bb 2448plusmn 072Ac 1429plusmn 092BaT3 1426plusmn 048Aa 1646plusmn 147Aa 1587plusmn 025Ca 1898plusmn 089Bb 1628plusmn 065BaT4 1426plusmn 063Aa 1356plusmn 037Ba 1399plusmn 038Ca 1183plusmn 011Cb 1628plusmn 097Bc

)e values are given as meanplusmn standard deviation (n 3) Different capital letters within a column indicate significant differences among treatments(ple 005) Different small letters within a row indicate significant differences due to storage time (ple 005) T1 control T2 gelatin coating only T3 gelatin+MEO (05) coating T4 gelatin +MEO (1) coating

0

5

10

15

20

25

30

0 3 7 10 13

Wei

ght l

oss (

)

Storage time (days)


Figure 2 Weight loss of coated and uncoated strawberries duringstorage at 4degC for 13 days Vertical bars represent the standarddeviation (n 3)


period also in coated (T2 T3 and T4) and uncoated (T1)strawberries )e decrease in TPC through storage could beattributed to the degradation of anthocyanins during thesenescence period [38] Gelatin coating alone (T2) slightlyreduces TPC loss Li et al [36] using starch-based coatingfor strawberries preservation noted that coating reduces thelosses of TPC)e same result was obtained by Gol et al [16]using chitosan-based coating Surprisingly gelatin +MEO(1) (T4) coating was the most effective treatment thatlimits losses in TPC after 10 days of storage In a similartrend Oms-Oliu et al [39] concluded that coating treatmentwith chitosan starch and cinnamon EO promotes enzy-matic activity of phenylalanine ammonia lyase responsiblefor the accumulation of total phenols in strawberries

323 Firmness Color and Decay Rate Firmness is one ofthe most important quality parameter for strawberries

acceptance In our study gelatin-based coatings did notaffect significantly firmness of the strawberry fruit duringcold storage and the firmness of the fruits was maintained(Table 2) Our results agree with those obtained by Pover-enov et al [34] for red bell peppers using chitosangelatincoating Amal et al [32] and Petriccione et al [30] alsoshowed that strawberries lose their firmness during thestorage due to cell walls degradation during storage )esame authors pointed out the positive effect of coating tolimit firmness loss )e color parameter is usually used toevaluate the quality and ripening degree of fruits )e resultsobtained in this study are shown in Table 2 and colorchanges were estimated by L and chroma values

Despite that all treatments (from T1 to T4) show sig-nificant decrease in the estimated values gelatin coatingclearly slows down these changes Similar trends were re-ported by Petriccione et al [30] and Hernandez-Muntildeoz et al[40] Velickova et al [41] reported that coatings protect

Table 2 Firmness and color of coated and uncoated strawberries during storage at 4degC for 13 days


Firmness (N)

T1 214plusmn 056Aab 307plusmn 062Aa 305plusmn 025Aa 252plusmn 023Aab 129plusmn 086AbT2 287plusmn 081Aab 387plusmn 099Aab 486plusmn 057Aa 360plusmn 025Bab 216plusmn 157AbT3 293plusmn 092Aa 401plusmn 138Aa 465plusmn 207Aa 477plusmn 027Ca 295plusmn 117AaT4 224plusmn 023Aa 301plusmn 040Aa 341plusmn 113Aa 277plusmn 062ABa 291plusmn 092Aa

Llowast value

T1 4616plusmn 092Aa 4213plusmn 225Aab 4368plusmn 178Aab 4093plusmn 258Abc 3711plusmn 099AcT2 4404plusmn 061Aa 4206plusmn 166Aab 4237plusmn 160Aab 4139plusmn 301Aab 3877plusmn 188ABbT3 4598plusmn 059Aa 4250plusmn 144Aab 4242plusmn 208Aab 4290plusmn 051Aab 4006plusmn 179ABbT4 3904plusmn 103Ba 4633plusmn 163Ab 4015plusmn plusmn 079Aa 4093plusmn 258Aa 4139plusmn 148Ba

Chroma value

T1 3031plusmn 837Aa 2422plusmn 187Aab 2136plusmn 210Aab 1947plusmn 111Aab 1756plusmn 352AbT2 2469plusmn 033Aa 2009plusmn 225Aab 1698plusmn 165Ab 1766plusmn 209Ab 2119plusmn 172AabT3 2377plusmn 278Aa 1888plusmn 224Aa 1946plusmn 165Aa 1826plusmn 114Aa 2009plusmn 395AaT4 3177plusmn 462Aa 2231plusmn 289Ab 1943plusmn 220Ab 1719plusmn 074Ab 2093plusmn 261Ab

)e values are given as meanplusmn standard deviation (n 3) Different capital letters within a column indicate significant differences among treatments(ple 005) Different small letters within a row indicate significant differences due to storage time (ple 005) T1 control T2 gelatin coating only T3 gelatin+MEO (05) coating T4 gelatin +MEO (1) coating Llowast lightness

Aa

AbAc

Ad

Ba

BbBc

Bd

Ca

BbCc

Bd

Aa

CbDc

Cd

0

05

1

15

2

25

0 3 7 10Storage time (days)


Tota

l phe

nolic

cont

ent (

mg

g)

Figure 3 Total phenolic content (TPC) of coated and uncoated strawberries during storage at 4degC for 10 days Vertical bars represent thestandard deviation (n 3) Bars with different small letters indicate significant differences due to storage time (ple 005)


fruits from advanced atmospheric dehydration and conse-quently delayed their senescence

Visual decay of uncoated (T1) and coated (T2 T3 andT4) strawberries during storage time at 4degC is shown inFigure 4 As it can be observed gelatin +MEO (1) (T4) wasthe most effective treatment protecting at least 60 ofstrawberries from decay after 13 days of cold storage whilegelatin alone (T2) was the lowest effective treatment Ourresults are in accordance with those obtained by Li et al [36]using a polysaccharide-based coating for strawberriespreservation)e high protection level in visual decay for T4treatment can be attributed to antimicrobial activity ofMEO as previously demonstrated with microbes being thefirst responsible for strawberries decay

4 Conclusions

)is study shows the effectiveness of coating-based gelatin+MEO (1) for postharvest strawberries preservation up to13 days by delaying microbial growth Physicochemical andsensorial properties (weight loss TA TSS firmness colorand TPC) of coated strawberries were always better thanthose of the control Gelatin coating alone was not as ef-fective as gelatin incorporated with MEO )e use of thiscombination would be a good alternative to extend shelf lifeof strawberries and to limit the use of pesticides in post-harvest treatments

Data Availability

)e data used to support the findings of this study are in-cluded within the article

Conflicts of Interest

)e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

)is study was supported by the CNRST (Project noPPR201510)

References

[1] MAPMDREF Agriculture en Chiffres 2016 MinisteredrsquoAgriculture et Peche Maritime Morocco 2016

[2] AMPFR Note Festival Fruits Rouges 2017 AssociationMarocaine de Producteurs de Fruits Rouges au MarocMorocco 2017

[3] J Cheel C )eoduloz J A Rodrıguez P D S Caligari andG Schmeda-Hirschmann ldquoFree radical scavenging activityand phenolic content in achenes and thalamus from Fragariachiloensis ssp chiloensis F vesca and F times ananassa cvChandlerrdquo Food Chemistry vol 102 no 1 pp 36ndash44 2007

[4] M L B Almeida C F H Moura R Innecco A dos Santosand F R de Miranda ldquoPostharvest shelf-life and fruit qualityof strawberry grown in different cropping systemsrdquo AfricanJournal of Agricultural Research vol 10 no 43 pp 4053ndash4061 2015

[5] T J Avis C Martinez and R J Tweddell ldquoEffect of chlorineatmospheres on the development of Rhizopus rot [Rhizopusstolonifer] and gray mold [Botrytis cinerea] on storedstrawberry fruitsrdquo Canadian Journal of Plant Pathologyvol 28 no 4 pp 526ndash532 2006

[6] R K Dhall ldquoAdvances in edible coatings for fresh fruits andvegetables a reviewrdquo Critical Reviews in Food Science andNutrition vol 53 no 5 pp 435ndash450 2013

[7] J H Han Innovations in Food Packaging Elsevier AmsterdamNetherlands 2005

[8] C Bouchra M Achouri L M Idrissi Hassani andM Hmamouchi ldquoChemical composition and antifungal ac-tivity of essential oils of seven Moroccan Labiatae againstBotrytis cinerea Pers Frrdquo Journal of Ethnopharmacologyvol 89 no 1 pp 165ndash169 2003

[9] S Mohammadi H Aroiee M H Aminifard andV Jahanbakhsh ldquoIn vitro and in vivo antifungal activates ofthe essential oils of various plants against strawberry greymould disease agent Botrytis cinereardquo Archives of Phytopa-thology and Plant Protection vol 45 no 20 pp 2474ndash24842012

[10] A Fennane I Nechad J Al Figuigui F Errachidi T El Kamliand L Elghadraoui ldquoActivity in vitro of the oils of Rosmarinusofficinalis and Lavandula officinalis on the mycelial growth ofthree lettuce mushroomsrdquo International Journal of Scientificand Engineering Research vol 7 no 9 pp 160ndash171 2016

[11] M Oussalah S Caillet S Salmieri L Saucier andM LacroixldquoAntimicrobial and antioxidant effects of milk protein-basedfilm containing essential oils for the preservation of wholebeef musclerdquo Journal of Agricultural and Food Chemistryvol 52 no 18 pp 5598ndash5605 2004

[12] M A Rojas-Grau R J Avena-Bustillos C Olsen et alldquoEffects of plant essential oils and oil compounds on me-chanical barrier and antimicrobial properties of alginatendashapple puree edible filmsrdquo Journal of Food Engineering vol 81no 3 pp 634ndash641 2007

[13] L Sanchez-Gonzalez M Chafer A Chiralt and C Gonzalez-Martınez ldquoPhysical properties of edible chitosan films con-taining bergamot essential oil and their inhibitory action onPenicillium italicumrdquo Carbohydrate Polymers vol 82 no 2pp 277ndash283 2010

0

10

20

30

40

50

60

70

80

90

100

Visu

al d

ecay

()

ControlGelatin only

Gelatin + MEO 05Gelatin + MEO 1

0 3 7 10 13Storage time (days)

Figure 4 Visual decay of coated and uncoated strawberries duringstorage at 4degC for 13 days Vertical bars represent the standarddeviation (n 3)


[14] A P D A M Foganholi J F S Daniel D C SantiagoJ R Orives J P Pereira and T D J Faria ldquoComposiccedilatildeoquımica e atividade antifungica do oleo essencial de poejo emdiferentes estagios de desenvolvimentordquo Semina CienciasAgrarias vol 36 no 5 p 3091 2015

[15] A Ait-Ouazzou S Loran A Arakrak et al ldquoEvaluation of thechemical composition and antimicrobial activity of Menthapulegium Juniperus phoenicea and Cyperus longus essentialoils from Moroccordquo Food Research International vol 45no 1 pp 313ndash319 2012

[16] N B Gol P R Patel and T V R Rao ldquoImprovement ofquality and shelf-life of strawberries with edible coatingsenriched with chitosanrdquo Postharvest Biology and Technologyvol 85 pp 185ndash195 2013

[17] C Pagliarulo F Sansone S Moccia et al ldquoPreservation ofstrawberries with an antifungal edible coating using peonyextracts in Chitosanrdquo Food and Bioprocess Technology vol 9no 11 pp 1951ndash1960 2016

[18] M Ramos A Valdes A Beltran and M Garrigos ldquoGelatin-based films and coatings for food packaging applicationsrdquoCoatings vol 6 no 4 p 41 2016

[19] H-J Yang J-H Lee K-Y Lee and K Bin Song ldquoApplicationof gelatin film and coating prepared from dried alaska pollockby-product in quality maintanance of grape berriesrdquo Journalof Food Processing and Preservation vol 41 no 6 articlee13228 2017

[20] J Gomez-Estaca A Lopez de Lacey M C Gomez-GuillenM E Lopez-Caballero and P Montero ldquoAntimicrobial ac-tivity of composite edible films based on fish gelatin andchitosan incorporated with clove essential oilrdquo Journal ofAquatic Food Product Technology vol 18 no 1-2 pp 46ndash522009

[21] F M Fakhouri A C A Casari M Mariano et al ldquoEffect ofa gelatin-based edible coating containing cellulose nano-crystals (CNC) on the quality and nutrient retention of freshstrawberries during storagerdquo IOP Conference Series MaterialsScience and Engineering vol 64 article 012024 2014

[22] J M Jay M J Loessner and D A Golden Modern FoodMicrobiology Springer New York NY USA 7th edition2005

[23] C Patricia and AOAC International Official Methods ofAnalysis of AOAC International AOAC InternationalGaithersburg MD USA 16th edition 1997

[24] T Siriwoharn R E Wrolstad C E Finn and C B PereiraldquoInfluence of cultivar maturity and sampling on Blackberry(Rubus L Hybrids) anthocyanins polyphenolics and anti-oxidant propertiesrdquo Journal of Agricultural and FoodChemistry vol 52 no 26 pp 8021ndash8030 2004

[25] Y Shahbazi ldquoApplication of carboxymethyl cellulose andchitosan coatings containing Mentha spicata essential oil infresh strawberriesrdquo International Journal of Biological Mac-romolecules vol 112 pp 264ndash272 2018

[26] V S Bierhals M Chiumarelli and M D Hubinger ldquoEffect ofcassava starch coating on quality and shelf life of fresh-cutpineapple (Ananas comosus L Merril cv lsquoPerolarsquo)rdquo Journal ofFood Science vol 76 no 1 pp E62ndashE72 2011

[27] S BadrValorisation de Plantes Aromatiques et Medicinales duMaroc Valorisation de Plantes Aromatiques et Medicinales Parlrsquoanalyse Chimique et lrsquoEtude de la Bioactivite de Leurs HuilesEssentielles Editions Universitaires Europeennes SaarbruckenGermany 2010

[28] P Raquel A Kwiatkowsk E Clemente and Campos ldquoPost-harvest conservation of organic strawberries coated withcassava starch and chitosanrdquo Ceres vol 58 no 5 2015

[29] Y-J Shin H-Y Song and K B Song ldquoEffect of a combinedtreatment of rice bran protein film packaging with aqueouschlorine dioxide washing and ultraviolet-C irradiation on thepostharvest quality of lsquoGoharsquo strawberriesrdquo Journal of FoodEngineering vol 113 no 3 pp 374ndash379 2012

[30] M Petriccione F Mastrobuoni M Pasquariello et al ldquoEffectof chitosan coating on the postharvest quality and antioxidantenzyme system response of strawberry fruit during coldstoragerdquo Foods vol 4 no 4 pp 501ndash523 2015

[31] H M Dıaz-Mula M Serrano and D Valero ldquoAlginatecoatings preserve fruit quality and bioactive compoundsduring storage of sweet cherry fruitrdquo Food and BioprocessTechnology vol 5 no 8 pp 2990ndash2997 2012

[32] S H A Amal M M El-Mogy H E Aboul-Anean andB W Alsanius ldquoImproving strawberry fruit storability byedible coating as a carrier of thymol or calcium chloriderdquoJournal of Horticultural Science amp Ornamental Plants vol 2no 3 pp 88ndash97 2010

[33] S Y Wang and H Gao ldquoEffect of chitosan-based ediblecoating on antioxidants antioxidant enzyme system andpostharvest fruit quality of strawberries (Fragaria x aranassaDuch)rdquo LWT-Food Science and Technology vol 52 no 2pp 71ndash79 2013

[34] E Poverenov Y Zaitsev H Arnon et al ldquoEffects of a com-posite chitosanndashgelatin edible coating on postharvest qualityand storability of red bell peppersrdquo Postharvest Biology andTechnology vol 96 pp 106ndash109 2014

[35] A Hoda Khalil and M Shimaa Hassan ldquoAscorbic acidβ-carotene total phenolic compound and microbiologicalquality of organic and conventional citrus and strawberrygrown in Egyptrdquo African Journal of Biotechnology vol 14no 4 pp 272ndash277 2015

[36] L Li J Sun H Gao et al ldquoEffects of polysaccharide-basededible coatings on quality and antioxidant enzyme system ofstrawberry during cold storagerdquo International Journal ofPolymer Science vol 2017 Article ID 9746174 8 pages 2017

[37] M J Anttonen K I Hoppula R Nestby M J Verheul andR O Karjalainen ldquoInfluence of fertilization mulch colorearly forcing fruit order planting date shading growingenvironment and genotype on the contents of selectedphenolics in strawberry ( Fragaria times ananassa Duch) fruitsrdquoJournal of Agricultural and Food Chemistry vol 54 no 7pp 2614ndash2620 2006

[38] R I Ventura-Aguilar S Bautista-Bantildeos G Flores-Garcıaand L Zavaleta-Avejar ldquoImpact of chitosan based ediblecoatings functionalized with natural compounds on Colle-totrichum fragariae development and the quality of straw-berriesrdquo Food Chemistry vol 262 pp 142ndash149 2018

[39] G Oms-Oliu R Soliva-Fortuny and O Martın-BellosoldquoEdible coatings with antibrowning agents to maintain sen-sory quality and antioxidant properties of fresh-cut pearsrdquoPostharvest Biology and Technology vol 50 no 1 pp 87ndash942008

[40] P Hernandez-Muntildeoz E Almenar V D Valle D Velez andR Gavara ldquoEffect of chitosan coating combined with post-harvest calcium treatment on strawberry (Fragaria times ananassa)quality during refrigerated storagerdquo Food Chemistry vol 110no 2 pp 428ndash435 2008

[41] E Velickova E Winkelhausen S Kuzmanova V D Alvesand M Moldatildeo-Martins ldquoImpact of chitosan-beeswax ediblecoatings on the quality of fresh strawberries (Fragaria ana-nassa cv Camarosa) under commercial storage conditionsrdquoLWT- Food Science and Technology vol 52 no 2 pp 80ndash922013


Hindawiwwwhindawicom

International Journal of

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Zoology

Hindawiwwwhindawicom Volume 2018

Anatomy Research International

PeptidesInternational Journal of



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The Scientific World Journal

Volume 2018


BioinformaticsAdvances in

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Cell BiologyInternational Journal of



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ArchaeaHindawiwwwhindawicom Volume 2018


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Submit your manuscripts atwwwhindawicom

natures like protein lipids and polysaccharides )echemical and physical characteristics of the biopolymer useddetermine their efficacy to be used for food shelf life pro-longation )ese coatings can also become bioactive by theincorporation of biomolecules with antimicrobial and an-tioxidant properties

Essential oils have been largely used to preserve thequality of food due to their antimicrobial and antioxidantactivities [8ndash13] MEO is considered as one of the mosteffective essential oils against a large spectrum of bacterialand fungal strains [14 15] Several biopolymers-basedcoating incorporated with EOs have been used for straw-berries preservation [16 17] Due to their mechanical re-sistance barrier properties and sensorial acceptabilitygelatin has been largely used to prolong the shelf life of foodssuch as meat and fish [18ndash20] However to the best of ourknowledge the effect of gelatin coating on strawberrypreservation is limited and has been used in only a fewstudies [21]

In this sense our work aims at evaluating the combinedeffect of gelatin-based coating and MEO on physicochem-ical microbiological and sensorial characteristics ofstrawberries during storage under refrigeration

2 Materials and Methods

21 Raw Material Fresh strawberries (Sabrina) were col-lected from the experimental center of the National Instituteof Agronomic Research (Larache Morocco) during theseason of 2018 )ey were transported to the laboratoryNoninjured fruit were sorted for their uniformity in sizefirmness and color

22 Essential Oil Isolation Essential oil used in this in-vestigation was obtained by hydrodistillation from plants ofM pulegium collected in the northeastern part of Morocco(Oujda) )e taxonomic identities of the plants were con-firmed by comparing voucher specimens with those ofknown identity previously deposited in the National Her-barium of the Scientific Institute of Rabat

23 Gelatin Coating Formation Twelve grams of gelatinpowder (HiMedia Laboratories Pvt Ltd India) was dis-solved in 300mL of sterile distilled water and stirred at 45degCfor 10min Sorbitol (Loba Chemie Pvt Ltd India) (ww ofgelatin) was added to increase mixture stability 15 and 3mLof MEO were added to prepare bioactive gelatin coating at05 and 1 respectively TWEENreg 80 was used as anemulsifier

After mixture homogenization washed strawberrieswere dipped into the prepared solution for about 90 secondsthey were filtered thereafter using a filter funnel and resetinto labeled plastic punnets Four treatments were prepared

T1 control (uncoated strawberries)T2 gelatin coating without MEOT3 gelatin coating with 05 MEOT4 gelatin coating with 1 MEO

)e punnets were packed with a plastic wrap and storedin at 4degC )e physicochemical microbiological and sen-sorial parameters were tested on the first day and after 3 710 and 13 days

24 Microbiological Parameters )e count of total aerobicmesophilic flora (TAMF) and yeasts and moulds (YM) wereperformed according to Jay et al [22] after 0 3 7 and 10days of storage

25 Physicochemical and Sensorial Parameters pH totalsoluble solids (TSS) and titratable acidity (TA) were mea-sured as described in official methods of analysis [23]

)e maturity index (MI) was calculated as the ratio ofTSS and TA Fruit firmness was measured using a TA1texture analyzer (Ametek Lloyd Instruments Ltd UK) bysetting crosshead speed at 1mms and penetration depth at10mm Firmness expressed in N is the textural parametermeasured on the resulting force-distance curve

Fruit color was measured using CR-300 Chroma Meter(Konica Minolta CR-300 Osaka Japan) and Llowast (lightness)alowast (redness) and blowast (yellowness) values were obtained )echroma value C was calculated using the following equation

C a2

+ b2

1113872 111387312

(1)

)e difference between the initial and final weight wasconsidered as the total weight loss Strawberry samples wereweighed at the beginning (ie 0 days) and at the end of eachstorage interval )e results were expressed as weight losspercentage Total phenolic content (TPC) was determinedusing the FolinndashCiocalteau reagent (Solvachim LaboratoiresCasablanca) according to the method described by Sir-iwoharn et al [24] using gallic acid (Loba Chemie Pvt LtdIndia) as standard )e calibration curve was plotted bymixing 05mL of 10 50 100 200 and 400 ppm gallic acidsolution with 75mL of distilled water and 05mL of theFolinndashCiocalteau reagent 05mL of the strawberry samplewas added to 75mL of distilled water and 05mL of theFolinndashCiocalteau reagent 05mL of distilled water was usedfor blank preparation Afterwards all tubes were mixed witha vortex and held for 10min at room temperature )en3mL of sodium carbonate (20) solution was added to eachtest tube Tubes were stirred and placed in a water bath at40degC for 20min and then cooled directly in an ice bath for3min )e absorbance of all samples was measured usinga 755 nm UV spectrophotometer (JP Selecta SA Spain)TPC was expressed in mg gallic acid equivalent (GAE)g dryweight

Visual decay was determined by a visual inspection at 03 7 10 and 13 storage days and was estimated as thenumber of infected fruits divided by the total number offruits expressed in percentage ()

26 Statistical Analysis All measurements were done intriplicates Data analyses were performed by one-wayanalysis of variance (ANOVA) followed by Tukeyrsquos posthoc tests to evaluate significant differences among the










0

1

2

3

4

5

6

0 3 7 10

Tota

l flor

a cou

nt (l

og C

FUg

)

Storage time (days)



(a)

0

1

2

3

4

5

6

0 3 7 10Ye

asts

and

mou

lds c

ount

(log

CFU

g)

Storage time (days)


(b)











pH


TSS (brix)


TA ()


Maturity index ()



0

5

10

15

20

25

30

0 3 7 10 13

Wei

ght l

oss (

)

Storage time (days)










Firmness (N)


Llowast value


Chroma value



Aa

AbAc

Ad

Ba

BbBc

Bd

Ca

BbCc

Bd

Aa

CbDc

Cd

0

05

1

15

2

25



Tota

l phe

nolic

cont

ent (

mg

g)





4 Conclusions


Data Availability




Acknowledgments


References














0

10

20

30

40

50

60

70

80

90

100

Visu

al d

ecay

()

ControlGelatin only




































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018










0

1

2

3

4

5

6

0 3 7 10

Tota

l flor

a cou

nt (l

og C

FUg

)

Storage time (days)



(a)

0

1

2

3

4

5

6

0 3 7 10Ye

asts

and

mou

lds c

ount

(log

CFU

g)

Storage time (days)


(b)











pH


TSS (brix)


TA ()


Maturity index ()



0

5

10

15

20

25

30

0 3 7 10 13

Wei

ght l

oss (

)

Storage time (days)










Firmness (N)


Llowast value


Chroma value



Aa

AbAc

Ad

Ba

BbBc

Bd

Ca

BbCc

Bd

Aa

CbDc

Cd

0

05

1

15

2

25



Tota

l phe

nolic

cont

ent (

mg

g)





4 Conclusions


Data Availability




Acknowledgments


References














0

10

20

30

40

50

60

70

80

90

100

Visu

al d

ecay

()

ControlGelatin only




































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018










pH


TSS (brix)


TA ()


Maturity index ()



0

5

10

15

20

25

30

0 3 7 10 13

Wei

ght l

oss (

)

Storage time (days)










Firmness (N)


Llowast value


Chroma value



Aa

AbAc

Ad

Ba

BbBc

Bd

Ca

BbCc

Bd

Aa

CbDc

Cd

0

05

1

15

2

25



Tota

l phe

nolic

cont

ent (

mg

g)





4 Conclusions


Data Availability




Acknowledgments


References














0

10

20

30

40

50

60

70

80

90

100

Visu

al d

ecay

()

ControlGelatin only




































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018








Firmness (N)


Llowast value


Chroma value



Aa

AbAc

Ad

Ba

BbBc

Bd

Ca

BbCc

Bd

Aa

CbDc

Cd

0

05

1

15

2

25



Tota

l phe

nolic

cont

ent (

mg

g)





4 Conclusions


Data Availability




Acknowledgments


References














0

10

20

30

40

50

60

70

80

90

100

Visu

al d

ecay

()

ControlGelatin only




































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018




4 Conclusions


Data Availability




Acknowledgments


References














0

10

20

30

40

50

60

70

80

90

100

Visu

al d

ecay

()

ControlGelatin only




































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018

































Volume 2018

Zoology











Volume 2018

















Advances in




Enzyme Research





Volume 2018


gelatin-based edible coating combined with mentha pulegium...

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