Effect of spice incorporated starch edible film wrapping on shelf life of white shrimps

Research Article

Received:6October2015Revised:10December2015Accepted article published:21January2016Published online in Wiley Online Library: (https://www.360docs.net/doc/4e13888456.html,)DOI10.1002/jsfa.7638

E?ect of spice-incorporated starch edible?lm wrapping on shelf life of white shrimps stored at di?erent temperatures

Sivarajan Meenatchisundaram,a Chandra Mohan Chandrasekar,b Lalitha Priya Udayasoorian,b Rakhavan Kavindapadi Rajasekaran,b Radha krishnan Kesavan,c Babuskin Srinivasan d and Sukumar Muthusamy b*

Abstract

BACKGROUND:White shrimps(Litopenaeus vannamei)are a major aquaculture product in the world?shery market.The main aim of this study was to investigate the e?ect of clove-and cinnamon-assimilated starch edible?lms on the shelf life of white shrimps in terms of maintaining their freshness and other organoleptic properties.Physical,chemical,microbial and sensory qualities of edible?lm-wrapped white shrimps were studied until they reached their limit of acceptability during storage at di?erent temperatures(10and4°C).

RESULTS:Shrimp samples wrapped with spice-assimilated edible?lms showed lower bacterial counts.Shelf life extension of edible?lm-wrapped white shrimps was estimated to be14and12days for storage at10and4°C respectively.Reduced lipid oxidation and release of nitrogen base compounds were noted for edible?lm-wrapped shrimp samples.Good consumer acceptance was noted for edible?lm-wrapped shrimp samples through sensory evaluation.

CONCLUSION:The results of this study show that spice-fused edible?lms were e?ective in inhibiting the growth of microbial populations.Reductions in lipid oxidation and total volatile base nitrogen were also achieved through edible?lm wrapping of shrimps,which increased their consumer acceptance during sensory evaluation.

?2016Society of Chemical Industry

Keywords:shelf life;edible?lm;spices;white shrimps;food analysis;food microbiology

INTRODUCTION

Prawns are one of the highly exportable food commodities in the world.They are highly nutritious and tasty.There are di?erent grades of prawns available ranging from retail to export quality. In the mind of the average consumer who is about to purchase prawns,their freshness is of high priority.Freshness,although relative,can qualify somewhat high appeal of the desired product by its look,size and/or texture.It is important to study the shelf life of prawns for both retail and export qualities.Freshness can also be dependent on a number of physical parameters such as texture,pH,etc.and chemical parameters such as lipid oxidation, peroxide value,total volatile base nitrogen,etc.1Physical and chemical parameters have been reported to be associated with microbial load of fresh prawns.2Hence the control of microbial proliferation in prawns paves the way for extending the shelf life of prawns for both retail and export.In the past decade, many di?erent packaging systems have been studied for shelf life extension of a wide range of food products.The optimal packaging system for?shery products has not yet been achieved. Every packaging system,apart from its bene?ts and?aws,incurs additional costs that result in an increase in eventual price of the product.One solution could be the use of an edible?lm natural extract packaging system,as it can provide the key for cost-e?ective and e?cient packaging to extend the shelf life of highly perishable?shery products such as prawns.3In particular, this packaging system presents advantages such as extension of shelf life and retention of freshness of the given product.4It also provides excellent organoleptic properties more desirable to customers.

Inevitably,lipid peroxidation leads to the reduction of prawn freshness.The rate of discolouration of prawns is believed to underpin the balance between oxidation processes and enzymatic reduction.5Several studies have shown that edible coatings help to prolong the shelf life and preserve the quality of food products. Interaction with the surrounding environment during storage and processing is decreased to a minimum by coating,which ?Correspondence to:S Muthusamy,Centre for Food Technology,Anna University, Chennai,Tamilnadu,India.E-mail:sukumarcbt@https://www.360docs.net/doc/4e13888456.html,

a Central Leather Research Institute(CLRI),CSIR,Chennai,Tamilnadu,India

b Centre for Food Technology,Anna University,Chennai,Tamilnadu,India

c Central Institute of Technology,Kokrajhar,Assam,India

d JCT Colleg

e o

f Engineering&Technology,Coimbatore,Tamilnadu,India

J Sci Food Agric(2016)https://www.360docs.net/doc/4e13888456.html,?2016Society of Chemical Industry

https://www.360docs.net/doc/4e13888456.html, S Meenatchisundaram et al.

prevents spoilage.4On the other hand,the production of edible ?lms by polymerization of proteins and saccharides has been under study for incorporation of antimicrobial spices(e.g.clove and cinnamon)as a means to control microbial load in prawns.6 In particular,clove provides good antioxidant properties7–9and cinnamon provides good antimicrobial properties10,11to edible ?lms.In recent research studies,some reports proved that the use of highly concentrated spice extracts can hinder uptake of nutrients in the human intestine during long-term consumption.12 Finely ground spice powders can be used as an alternative to avoid this problem.In addition,use of spice powders in foods meets the current demands of consumers for mildly processed foods from natural products.

Thus the present study was aimed at evaluating the shelf life of prawns wrapped with edible?lm and stored at temperatures of 4and10°C.Physical,chemical and microbiological parameters of prawns were analysed to determine the e?ect of incorporating the spices clove and cinnamon into edible?lm.

MATERIALS AND METHODS

Raw materials

Clove(Syzygium aromaticum)and cinnamon(Cinnamomum cassia) were obtained from Nuts and Spices Supermarket(Chennai,India). All microbial strains were bought from the Microbial Type Culture Collection(MTCC)(Chandigarh,India).Shrimps were procured from chintadripet?sh market(Chennai,India)and transferred in insulated polystyrene boxes to the laboratory within30min.All chemicals(purity:EMPARTA ACS grade for analysis)were bought from a local supplier for Merck Millipore(Merck Specialities Pvt. Ltd).Microbial culture media and media components were bought from local suppliers for Hi-media Laboratories.

Particle size reduction of spices

Dry spice samples were frozen to?25°C in a freezing chamber and?rst milled in a co?ee grinder(to～5mm).The resulting coarse spice powders were frozen to?25°C and further milled in a Spex 8000M high-energy ball-milling machine(SPEX SamplePrep, Metuchen,NJ,USA)using a milling vial with440C stainless steel balls(0.25inch diameter)at a powder/ball ratio of1:10(w/w).The organic solvent n-hexane(998mL L?1)was used as the milling medium and oleic acid(900mL L?1)was used as the surfactant during milling.The amount of surfactant used was～50–70mL L?1 and the solvent used was about50%of the weight of the starting powder.Special care was taken to avoid any rise in temperature during the milling process.The ball-milling process was continued until a constant average particle size of80μm was achieved. The ball-milled(spice powder/n-hexane)dispersion was sub-jected to freeze-drying to remove excess n-hexane.The particle size-reduced spice powders were stored at?5°C for further use. Particle size analysis of spices

Particle size distributions of tamarind seed starch and ball-milled spice powders were measured with a laser di?raction system (HELOS-BR,Sympatec Inc.,Princeton,NJ,USA).Brie?y,10mg of sample was dispersed in3mL of deionized water and loaded into the laser di?raction system(laser wavelength632.8nm). WINDOX software(Sympatec Inc.,Princeton,NJ,USA)was used to interpret the absorption analysis results in order to?nd the particle size distribution of the sample using the Fraunhofer enhanced evaluation method.All determinations were performed in triplicate and results were expressed as mean particle size distri-bution±standard error(SE).

Antioxidant activity of S.aromaticum and C.cassia

Di?erent antioxidant activity assays were performed to anal-yse the e?ect of particle size reduction on spice properties. 2,2-Diphenyl-1-picrylhydrazyl(DPPH)free radical-scavenging, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) cation decolourization,total phenolic content(TPC)and total ?avonoid content(TFC)assays were carried out as described in our previous work.13

Antibacterial activity of S.aromaticum and C.cassia Antibacterial properties of particle size-reduced spices were evalu-ated using the agar well di?usion method as described in our pre-vious work.13Bacterial strains used for this study were Escherichia coli(MTCC40),Salmonella sp.(MTCC1169),Shigella?exneri(MTCC 1457),Vibrio parahaemolyticus(MTCC451),Vibrio cholerae(MTCC 3904),Pseudomonas aeruginosa(MTCC4673),Lactobacillus del-brueckii(MTCC911)and Brochothrix sp.(MTCC2963).

The minimum inhibitory concentration(MIC)of spices was eval-uated according to the method described in our previous work.13 The lowest concentration of spice extract required to inhibit visible growth of the tested microorganism was designated as the MIC. Gas chromatography/mass spectrometry(GC/MS)analysis

of spices

GC/MS analysis of spices was performed using an Agilent6890N gas chromatograph with an HP5973mass spectrometer detec-tor(Agilent Technologies,CA,USA)according to the method described in our previous study.13Particle size-reduced spice pow-ders were subjected to solvent(n-hexane)extraction prior to GC/MS https://www.360docs.net/doc/4e13888456.html,pounds in the extracts were identi?ed by matching their mass spectra and retention times with those of pure compounds whenever possible.The NIST(National Institute of Standards and Technology)Mass Spectra Library was also used as a reference.

Edible?lm preparation

Tamarind starch was dispersed in distilled water to give a50g L?1 polysaccharide suspension.The mixture was stirred constantly for40min using a magnetic stirrer at500rpm on a hot plate maintained at80°C to achieve complete dispersion.Preliminary evaluation was performed to assess the e?ectiveness of sorbitol and glycerol as plasticizers.It was revealed that glycerol was signi?cantly better than sorbitol,with the latter producing wet ?lms that were di?cult to peel.Accordingly,the dispersion was mixed with glycerol as a plasticizer at a loading of50g L?1along with xanthan gum as a gumming agent at a loading of30g L?1. Finally,cooking oil at20g L?1was added to act as an antifoaming agent.The mixture was then maintained at90°C for30min under continuous stirring to promote starch gelatinization.Particle size-reduced S.aromaticum and C.cassia were incorporated into the?lm solution at their respective MICs.Film solutions were cast over aluminium trays and dried in an electric tray dryer for3–4h at60°C.Films were peeled and stored in a vacuum desiccator for further use.Film thickness was determined using a Digimatic?Digital Micrometer(Mitutoyo Corporation,Kawasaki,Japan)as 0.45±0.09mm(average value obtained from estimation at ten random locations of edible?lm).

https://www.360docs.net/doc/4e13888456.html,/jsfa?2016Society of Chemical Industry J Sci Food Agric(2016)

E?ect of spice incorporated starch edible?lm at di?erent temperature conditions https://www.360docs.net/doc/4e13888456.html, Preparation of shrimp samples

Outer skins of shrimps were peeled in cold(4°C)aseptic conditions

and100g lots of peeled shrimps were wrapped with spice-fused

edible?lms.Edible?lm-wrapped and raw(control)shrimp samples

were sealed in polyethylene bags and stored at two di?erent

temperatures(10and4°C)for shelf life study.

Physical analysis

The physical parameter pH of edible?lm-wrapped shrimps

was analysed periodically(every second day)during shelf life

study using a digital pH meter(HI-2212,Hanna Instruments,

Woonsocket,RI,USA).A15g shrimp sample was homogenized

with30mL of deionized water,then the pH of the homogenized

sample was measured.14

Chemical analysis

The chemical parameters primary lipid oxidation,secondary lipid

oxidation,protein oxidation and total volatile base nitrogen were

analysed in both control and edible?lm-wrapped shrimps.

Peroxide value(PV)analysis

Primary lipid oxidation or PV15was measured in a5g shrimp

sample homogenized with30mL of acetic acid/chloroform solu-

tion.The homogenate was poured into a100mL conical?ask and

0.5mL of saturated potassium iodide solution was added.The mix-

ture was slightly heated,then30mL of distilled water was added

before titrating the solution against0.1mol L?1sodium thiosulfate.

PV was estimated using the formula

PV=[

(S?B)M∕sample weight

]

×1000(1)

where S is the sample titration value,B is the blank titration value and M is the molarity of sodium thiosulfate.Results were expressed as meq O

kg?1sample.

2-Thiobarbituric acid-reactive substance(TBARS)analysis Secondary lipid oxidation or TBARS analysis was done as described in our previous work.13A5g shrimp sample was used.Malon-dialdehyde(MDA)is one of the most abundant relatively stable end products generated during secondary lipid oxidation.The concentration of MDA was calculated from the calibration curve obtained using1,1,3,3-tetraethoxypropane(0–10mg L?1),a pre-cursor of MDA.Results were expressed as mg MDA kg?1sample.16

Protein oxidation(PO)analysis

PO analysis was carried out by measuring the total carbonyl content.17A5g shrimp sample was homogenized in20mL of 0.15mol L?1KCl bu?er for60s using a homogenizer.Two0.1mL aliquots of homogenate were transferred to Eppendorf vials. Proteins were precipitated in both aliquots by adding1mL of 100mL L?1trichloroacetic acid(TCA)and centrifuging at5000×g for5min.One pellet was treated with1mL of2mol L?1HCl(pro-tein quanti?cation)and the other with1mL of2mol L?1HCl containing2g L?12,4-dinitrophenylhydrazine(carbonyl content determination).Both samples were incubated for1h at room tem-perature,with shaking every20min.After incubation,0.8mL of 100mL L?1TCA was added.Each sample was vortexed for30s, centrifuged at5000×g for5min and the supernatant removed. The pellet was washed three times with1mL of ethanol/ethyl acetate(1:1v/v)and then dried.Finally,the pellet was dissolved in2mL of6mol L?1guanidine-HCl in20mmol L?1sodium phos-phate bu?er(?nal pH6.5),stirred and centrifuged at5000×g for 2min to remove insoluble fragments.Protein concentration was calculated from the absorbance at280nm using bovine serum albumin as a standard.The amount of carbonyls was expressed as nmol carbonyl mg?1protein using an adsorption coe?cient of 21.0L mmol?1cm?1at370nm for protein hydrazones.

Total volatile base nitrogen(TVBN)analysis

TVBN was determined according to the micro-di?usion method.18 Brie?y,1mL of TVBN reagent was placed in the inner well of a Conway unit.Then1mL of TCA extract of peeled shrimp(～0.25g) sample was placed in the outer well,followed by1mL of saturated potassium carbonate.The Conway unit was closed,rotated in clockwise and anticlockwise directions and incubated at room temperature for3h.Then incubated TVBN reagent from the inner well was titrated with0.02mol L?1H

until the blue colour changed to https://www.360docs.net/doc/4e13888456.html,BN values were calculated using the formulae

[N]=14×a×b(2)

TVBN=([N]∕0.25)×100(3)

where[N]is the concentration of nitrogen,14is the molecular

weight of N,a is the molarity of H

and b is the volume of H

4 (titration value).TVBN values were expressed as mg N per100g sample.

Microbial analysis

Shrimp samples of10g were?rst homogenized(PT-MR-2100, Kinematica AG,Lucerne,Switzerland)aseptically with90mL of 1mL L?1peptone water,then serial dilutions were made using 1mL L?1sterile peptone water.The microbial parameters total viable count(TVC),pseudomonads(PM),lactobacilli(LAB),Enter-obacteriaceae(EB),yeasts and moulds(Y&M)and Brochothrix thermosphacta(BT)were enumerated.Serially diluted homog-enized shrimp samples of100μL were used for inoculation of agar plates.Microbial colonies were counted by digital colony counter.All microbial enumeration results were expressed in log colony-forming units(CFU)g?1.

TVC was enumerated using plate count agar with incubation at 37°C for48h.PM were enumerated using Pseudomonas agar base supplemented with cetrimide–fucidin–cephaloridine with incu-bation at25°C https://www.360docs.net/doc/4e13888456.html,B were enumerated using Lactobacillus MRS agar with incubation at37°C for72h.EB were enumerated using violet red bile glucose agar with incubation at30°C for48h. Y&M were enumerated using potato dextrose agar with incubation at25°C for72h.BT was enumerated using streptomycin thallous acetate agar with incubation at25°C for48h.

Sensory analysis

Sensory analysis was done with both trained and untrained pan-els consisting of?ve and11members respectively.Three sam-ples from two batches of edible?lm-wrapped shrimps stored at di?erent temperatures(10and4°C)were given to the panellists for sensory evaluation.Panellists were asked to give a score for each batch by evaluating all three samples.A nine-point hedonic scale was used for sensory scoring by trained panellists(9=like extremely,8=like very much,7=like moderately,6=like slightly,

J Sci Food Agric(2016)?2016Society of Chemical Industry https://www.360docs.net/doc/4e13888456.html,/jsfa

https://www.360docs.net/doc/4e13888456.html, S Meenatchisundaram et al.

5=neither like nor dislike,4=dislike slightly,3=dislike moder-ately,2=dislike very much,1=dislike extremely).A?ve-point hedonic scale was used for sensory scoring by untrained panel-lists(5=very good,4=good,3=moderate,2=bad,1=very bad). Scores of5and3were taken as acceptable limits for the nine-point and?ve-point hedonic scales respectively.The organoleptic vari-ables colour,odour,texture,mouthfeel and taste were taken as analysis parameters.Raw shrimps were used for colour,odour and texture evaluations.Cooked shrimps were used for sensory evalu-ation of mouthfeel and taste.

Statistical analysis of data

Each parameter was analysed three times using di?erent sam-ples during each sampling day(2×3).Thus two batches of edible ?lm-wrapped shrimps with control samples were stored at di?er-ent temperatures of4and10°C for all sampling days(60days).All physical,chemical and microbial parameters were analysed for sig-ni?cant di?erences of the data using Excel2010.Two-way analysis of variance(ANOVA)was done for determining mean di?erences for tested parameters,to establish those that di?ered signi?cantly at P<0.05.

RESULTS AND DISCUSSION

Antioxidant and antibacterial activity of S.aromaticum and C.cassia

In our initial?lm preparation studies19,Ball milled spice pow-ders were sampled at di?erent time intervals and they were ana-lyzed for its particle size,antioxidant and antibacterial properties. S.aromaticum spice powder with particle size of180μm was found to be rich in free radical quenchers and electron donors with high DPPH and ABTS assay values of9.12±0.31and5.32±0.12μmol TE/g respectively.Total phenolic content and total?avonoid con-tent of S.aromaticum was found to be26.24±0.54mg GAE/g and13.41±0.33mg quercetin/g respectively.This,high pheno-lic and?avonoid content could be responsible for antioxidant activity of S.aromaticum.Similar observations were reported by other researchers13,20.Rate of increase in antioxidant properties of S.aromaticum was high till its average particle size reaches85μm. Similar observation in antioxidant activity of C.cassia was noted with average particle size of92μm.But antioxidant properties of C.cassia were found to be much lower in comparison with S.aro-maticum.

Antibacterial properties of particle size reduced S.aromaticum and C.cassia was examined against panel of food pathogens and meat putrefying bacteria19.Antibacterial analysis results indicated that C.cassia with85μm particle size has high antibacterial activity when compared with S.aromaticum with92μm particle size.Minimum inhibitory concentration of S.aromaticum and C.cassia were found to be10mg mL?1and20mg mL?1.Thus these concentrations of ball milled spice powders were utilized for preparation of spice fused edible?lms.

Examination of active compounds

Eugenol(78.15%of total peak area)was found to be major active compound present in S.aromaticum19.Similar observations were made in other research studies13,21.Cinnamaldehyde(82.67%of total peak area)was found to be major active compound present in C.cassia13,19,22.The antibacterial activity of cinnamon is due to the presence of cinnamaldehyde,an aromatic aldehyde that inhibits amino acid decarboxylase activity23,and has been proven to be active against many pathogenic bacteria24.Cinnamon bark

also contains cinnamyl acetate,which increases the activity of the parent compound(Cinnamaldehyde)25.

Physical analysis of white shrimps

As a physical parameter,the pH of white shrimp depends mainly on the farming environment.The initial pH value of white shrimp reported by Mastromatteo et al.26was7.95,which is below the initial pH value of6.99±0.02estimated in our study.E?ect of edible?lm wrapping of raw shrimps on its pH are shown in Fig.1(a). In control samples,pH decreased drastically,which may be due to exponential growth of LAB.Production of lactic acid by lactobacilli may decrease the overall pH.13A gradual decrease in pH was noted in edible?lm-wrapped raw shrimps.pH decreased with signi?cant di?erence(P<0.05)from6.90±0.02to6.01±0.21and6.15±0.03 under storage at4and10°C respectively.

Chemical analysis of white shrimps

PV and TBARS

A gradual increase in PV(Fig.1(c))and MDA products of TBARS (Fig.1(b))was noted in both refrigerated and frozen edible ?lm-wrapped samples.There was a gradual increase in PV from 0.23±0.01to3.9±0.15and3.6±0.06meq O

kg?1in edible ?lm-wrapped shrimp samples stored at10and4°C respectively.

The initial PV noted was below1meq O

kg?1,which is in agree-ment with the?nding of Nirmal and Benjakul.27Ludor?and Meyer28suggested a PV scale for freshness of?shery products:

0–2mmol O

kg?1for very good,2–5mmol O

kg?1for good,

5–8mmol O

kg?1for acceptable and8–10mmol O

kg?1for

spoiled.PV at the end of storage was above3meq O

kg?1,which indicated good freshness of edible?lm-wrapped shrimp samples at the end of the storage period.The initial TBARS value was esti-mated to be2.16±0.08μg MDA kg?1in white shrimps,which was below the TBARS value of approximately5μg MDA kg?1reported by Bak et al.29This shows a low initial level of lipid oxidation in fresh white shrimps.A gradual increase in TBARS from2.16±0.02 to4.3±0.11and3.91±0.03μg MDA kg?1was noted in edible ?lm-wrapped shrimp samples stored at10and4°C respectively. This increase may be due to the production of lipase and phos-pholipase by pseudomonads,which cleave fat to release free fatty acids(prone to lipid oxidation).30Control samples showed a drastic increase in both PV and TBARS.Signi?cant di?erences (P<0.05)from control samples were noted for both PV and TBARS of edible?lm-wrapped shrimp samples.

All samples showed a gradual increase in PO,but no signi?cant e?ect of edible?lms on PO values was noted(Fig.1(d)).Lipids are more prone to oxidation,thus protein oxidation was found to be signi?cantly small compared with lipid oxidation.

TVBN

Spoiled ice-stored?shery products have high levels of TVBN. Typically,TVBN serves as quality indicator and is widely utilized to estimate the freshness of?shery products.31The initial TVBN value of white shrimp was estimated to be8.3±0.12mg N per 100g,which was less than the TVBN value of9.96±0.86mg N per100g reported by Okpala et al.31The TVBN analysis results for edible?lm-wrapped shrimp samples are shown in Fig.1(e). Control samples stored at10and4°C showed a drastic increase

https://www.360docs.net/doc/4e13888456.html,/jsfa?2016Society of Chemical Industry J Sci Food Agric(2016)

E?ect of spice incorporated starch edible ?lm at di?erent temperature conditions

https://www.360docs.net/doc/4e13888456.html,

(a)

(b)

(c)

(e)

(d)

4.5

5.5

66.5

7.5

p H

Days of Storage

T B A R S (μg o f M D A k g –1)

Days of Storage

12345678P V (m e q O 2 k g –1)

Days of Storage

P O (n m o l C a r b o n y l m g –1 p r o t e i n )

Days of Storage

51015202530354045T V B N (m g N p e r 100 g )

Days of Storage

Figure 1.Physical and chemical parameters of edible ?lm-wrapped white shrimps (E +S):e?ect of edible ?lm on (a)pH,(b)thiobarbituric acid-reactive substances (TBARS),(c)peroxide value (PV),(d)protein oxidation (PO)and (e)total volatile base nitrogen (TVBN).

in TVBN from 8.3±0.12to 40.3±0.15and 38.53±1.70mg N per 100g respectively.Edible ?lm-wrapped shrimp samples showed decreased production (compared with controls)of volatile base nitrogen compounds.A gradual increase in TVBN from 8.3±0.12to 22.5±0.40and 20.7±1.22mg N per 100g was noted for edible ?lm-wrapped shrimp samples stored at 10and 4°C respectively.Progressive TVBN increases in untreated Paci?c white shrimp specimens during iced storage have been reported previously by Huang et al.32Signi?cant di?erences (P <0.05)in TVBN were noted between control and edible ?lm-wrapped shrimp samples.An acceptability scale for TVBN values of raw shrimps has been proposed:<12mg N per100g for fresh,12–20mg N per100g for edible but slightly decomposed,20–25mg N per100g for border-line and >25mg N per 100g for inedible and decomposed.33TVBN values of shrimps at the end of the storage period were found to be slightly above 20,indicating borderline acceptability.Hence it is evident that edible ?lm treatment suppresses the production of TVBN and also gives more acceptability in sensory evaluation of odour.

Microbial analysis of white shrimps Total viable count

The International Commission on Microbiological Speci?cations for Foods (ICMSF)has stipulated a TVC of 7log CFU g ?1for frozen shrimps.31A recent report showed an initial TVC value of 4.45±0.09log CFU g ?1in Paci?c white shrimp,31which is above our initial TVC value of 2.99±0.10log CFU g ?1.Other authors reported initial bacterial counts of 4.19log CFU g ?1and 1.3×105CFU g ?1for white shrimps.3,34An initial Aerobic Plate Count (APC)value of 5.24log CFU g ?1for frozen shrimps has also been reported by Cadun et al.35These di?erences in initial micro-bial load may be due to the in?uence of farming environment.36Di?erences in TVC of shrimp samples are depicted in Fig.2(a).Ini-tially,a slow and gradual increase in TVC was noted for edible ?lm-wrapped shrimp samples.However,at the end of the stor-age period the growth rate increased signi?cantly,which may be due to adaptability of microbes to the given environment.Control samples of raw shrimps showed rapid growth in TVC values,which di?ered signi?cantly (P <0.05)from those of edible ?lm-wrapped

J Sci Food Agric (2016)

?2016Society of Chemical Industry https://www.360docs.net/doc/4e13888456.html,/jsfa

https://www.360docs.net/doc/4e13888456.html,

S Meenatchisundaram et

al.

(a)

(b)

(c)

(d)

(e)

(f)

12345678

10T V C (l o g C F U g –1)

Days of Storage

P s e u d o m o n a d s (l o g C F U g –1)

Days of Storage

L a c t o b a c i l l i (l o g C F U g –1)

Days of Storage E n t e r o b a c t e r i a c e a e (l o g C F U g –1)

Days of Storage

Y e a s t a n d m o u l d s (l o g C F U g –1)

Days of Storage

B r o c h o t h r i x t h e r m o s p h a c t a (l o g

C F U g –1)

Days of Storage

Figure 2.Microbial parameters of edible ?lm-wrapped white shrimps (E +S):e?ect of edible ?lm on (a)total volatile count (TVC)and growth of (b)pseudomonads,(c)lactobacilli,(d)Enterobacteriaceae,(e)yeasts and moulds and (f)Brochothrix thermosphacta .

https://www.360docs.net/doc/4e13888456.html,C of edible ?lm-wrapped shrimp samples exceeded 7log CFU g ?1on days 22and 30of storage at 10and 4°C respec-tively.Thus the shelf life of edible ?lm-wrapped shrimps was esti-mated as 21and 29days for storage at 10and 4°C respectively.Pseudomonads

The initial PM count was estimated to be 1.63±0.08log CFU g ?1,which was less than the 2log CFU g ?1reported by Mastromatteo et al.26Di?erences in PM count of shrimp samples are depicted in Fig.2(b).Control samples showed a drastic increase in PM count at both storage temperatures.A long lag phase of PM growth was observed in edible ?lm-wrapped shrimp samples stored at 4°C and an increase in growth was noted at the end of storage shelf life.Signi?cant di?erences (P <0.05)in PM growth were noted between control and edible ?lm-wrapped samples stored at 10and 4°C.The decrease in PM growth rate in edible ?lm-wrapped

shrimp samples may be due to active compounds of clove and cinnamon present in the edible ?lm.13

Lactobacilli

LAB growth is one of the important factors in?uencing the physical parameters of stored shrimps,especially pH,which decreases as LAB growth https://www.360docs.net/doc/4e13888456.html,B counts in shrimp samples were enumerated and are depicted in Fig.2(c).Initial LAB counts in shrimp were reported as 2.5and 1.4log CFU g ?1by Nirmal and Benjakul 27and Mejlholm et al.37respectively.The latter value is in agreement with our estimated initial LAB count of 1.53log CFU g ?1.A long lag phase of LAB growth was noted in edible ?lm-wrapped shrimp samples stored at 4°C:1.53–2.19log CFU g ?1for 22days.After day 22of storage a gradual increase in LAB growth rate was noted.Control samples stored at 4°C and edible ?lm-wrapped shrimp samples stored at 10°C showed more or less

https://www.360docs.net/doc/4e13888456.html,/jsfa ?2016Society of Chemical Industry

J Sci Food Agric (2016)

E?ect of spice incorporated starch edible?lm at di?erent temperature conditions https://www.360docs.net/doc/4e13888456.html,

the same growth rate.Control samples stored at10°C showed a drastic increase in LAB growth.Signi?cant di?erences(P<0.05)in LAB growth were noted between control and edible?lm-wrapped shrimp https://www.360docs.net/doc/4e13888456.html,B may inhibit the growth of other bacteria by their production of lactic acid and bacteriocins.38However, minimal LAB growth in all samples might not be enough to produce su?cient amounts of antimicrobial agents.Therefore LAB did not have any inhibition e?ect on other bacteria,as evidenced by the growth of other bacteria in shrimp samples. Enterobacteriaceae

EB are among coliforms,indicator organisms for growth of pathogens.Thus EB count plays a major role of indication for growth of food pathogens.The acceptable limit of EB load has been set as3log CFU g?1for consumption of?shery products.39 EB counts of shrimp samples are depicted in Fig.2(d).The initial EB count in shrimp was reported as2.5log CFU g?1by Nirmal and Benjakul,27which is higher than our estimated initial EB count of 1.26log CFU g?1.Edible?lm-wrapped shrimp samples showed an acceptable level of EB growth at both storage temperatures during the estimated shelf life period.Control samples showed a drastic increase in EB count.Signi?cant di?erences(P<0.05)in EB growth were noted between control and edible?lm-wrapped shrimp samples.

Yeasts and moulds

Yeast growth plays an important role in putrefaction of highly perishable food products stored under cold conditions.Yeasts promote fermentation in most food products,hence it becomes vital to enumerate the yeast count in food samples.Although moulds do not play a major role in putrefaction of?shery products, some moulds are harmful for human consumption.Thus enumer-ation of moulds is also important.Y&M counts were enumerated and are depicted in Fig.2(e).Y&M growth showed signi?cant di?erences(P<0.05)between control and edible?lm-wrapped shrimp samples.A gradual increase in Y&M growth was noted in edible?lm-wrapped shrimp samples stored at both temperatures. Brochothrix thermosphacta

BT is one of the major putrefying organisms of?shery products in cold storage.40The initial BT count in shrimp was reported as 2.0log CFU g?1by Fall et al.,40in agreement with our estimated initial BT count of2.09log CFU g?1.Initial suppression of BT growth was noted in edible?lm-wrapped shrimps in storage(Fig.2(f)). Then a gradual increase and signi?cant di?erence(P<0.05)in BT growth were noted in edible?lm-wrapped shrimp samples stored at10and4°C.Control samples showed a higher BT growth rate than edible?lm-wrapped samples,with no initial suppression of BT growth.

Sensory analysis

Edible?lm-wrapped shrimps stored at10and4°C were subjected to sensory analysis for acceptability of colour,texture,odour, mouthfeel and taste by two consumer panels.The?rst panel con-sisted of11untrained members.Each had a scoring slip to evalu-ate the edible?lm-wrapped shrimps stored at both10and4°C.A ?ve-point hedonic scale was used for scoring.Mean±SE for each parameter was calculated and taken as sample score.An accept-able score was set as3=moderate.The second panel comprised ?ve trained members and was used for sensory evaluation with a nine-point hedonic scale.

Table1gives the sensory evaluation scores for edible?lm-wrapped shrimps stored at two temperatures(10and4°C).All organoleptic variables were within the acceptable range for edible ?lm-wrapped shrimp samples at di?erent days of storage.In the trained panel scoring,shrimp colour was of marginal acceptability, with a score of5.60±0.50at day20of10°C storage,which may corroborate the colour score of4.19±0.12by the untrained panel. Taste scores of both trained and untrained panels were in the highly acceptable range for samples stored at10°C.For samples stored at4°C,texture scores of the trained panel averaged only 4.40±0.50at day20of storage,which is not within the acceptable limit.The untrained panel scoring on these samples produced a similar result,with a marginal acceptability score of3.91±0.12. As the texture scores were unacceptable for samples stored at 4°C,mouthfeel scores were also a?ected,showing borderline acceptance.Odour,taste and colour scores re?ected high accept-ability of samples stored at4°C.Hence it was found that edible ?lm-wrapped white shrimps showed good consumer acceptance up to day20for samples stored at10°C,but texture scores of samples stored at4°C showed less acceptance,which might be due to increased drip loss.Sensory evaluation after day20of storage was not conducted,since most microbial evaluations showed exponential growth in edible?lm-wrapped shrimps after day20of storage.

Table1.Sensory scores for white shrimps wrapped with edible?lm after5,10,15and20days of storage at10and4°C

Trained panel scores Untrained panel scores

Storage Sample Variable5days10days15days20days5days10days15days20days

10°C1Colour87.20±0.20 6.60±0.24 5.60±0.5055 4.64±0.15 4.19±0.12 2Odour87.80±0.207.00±0.54 6.40±0.455 4.55±0.15 4.64±0.15

3Texture887.40±0.24 6.40±0.5055 4.64±0.154±0.13

4Mouthfeel887.40±0.24 6.60±0.2455 4.73±0.144±0.53

5Taste87.80±0.207.60±0.24 6.80±0.2055 4.82±0.12 4.64±0.15 4°C1Colour8887.20±0.25 4.82±0.12 4.46±0.15 4.28±0.14 2Odour87.60±0.247.00±0.31 6.40±0.245 4.64±0.15 4.37±0.15 4.19±0.12

3Texture8 6.80±0.20 5.40±0.50 4.40±0.505 4.73±0.14 4.37±0.15 3.91±0.09

4Mouthfeel87 5.80±0.37 5.00±0.445 4.73±0.23 4.55±0.15 4.19±0.12

5Taste87.60±0.24 6.40±0.24 5.80±0.3755 4.46±0.15 4.46±0.15 Data are mean±SE.

J Sci Food Agric(2016)?2016Society of Chemical Industry https://www.360docs.net/doc/4e13888456.html,/jsfa

https://www.360docs.net/doc/4e13888456.html, S Meenatchisundaram et al.

CONCLUSIONS

The e?ect of spice-incorporated edible?lms on the shelf life of white shrimp(L.vannamei)was studied,resulting in shelf life esti-mates of up to21days(10°C)and29days(4°C)of storage, based on acceptable levels of TVC,EB,PV,TVBN and TBARS.Sen-sory assessment of organoleptic properties showed the consumer acceptance levels for edible?lm-wrapped shrimps.Reductions in lipid oxidation and TVBN were achieved through edible?lm wrap-ping of shrimps,which may have contributed to increased con-sumer acceptability during sensory evaluation. ACKNOWLEDGEMENTS

The authors sincerely express their greatest gratitude to DST,Sci-ence and Engineering Research Board(SERB/MOFPI/0022/2014) for?nancial support.

REFERENCES

1Olafsdottir G,Nesvadba P,Di Natale C,Careche M,Oehlenschlager J, Tryggvadottir SV et al.,Multisensor for?sh quality determination.

Trends Food Sci Technol15:86–93(2004).

2Castillo-Yanez FJ,Pacheco-Aguilar R,Marquez-Rios E,Lugo-Sanchez ME,and Lozano-Taylor J,Freshness loss in sierra?sh(Scombero-morus sierra)muscle stored in ice as a?ected by postcapture han-dling practices.J Food Biochem31:56–67(2007).

3Mu H,Chen H,Fang X,Mao J and Gao H,E?ect of cinnamaldehyde on melanosis and spoilage of Paci?c white shrimp(Litopenaeus vannamei)during storage.J Sci Food Agric92:2177–2182(2012).

4Kilincceker O,Dogan IS and Kucukoner E,E?ect of edible coatings on the quality of frozen?sh?llets.LWT–Food Sci Technol42:868–873 (2009).

5Frankel EN,Recent advances in lipid oxidation.J Sci Food Agric 54:495–511(1991).

6Giner MJ,Vegara S,Funes L,Marti N,Saura D,Micol V et al.,Antimicro-bial activity of food-compatible plant extracts and chitosan against naturally occurring micro-organisms in tomato juice.J Sci Food Agric 92:1917–1923(2012).

7Dorman HJD,Figueiredo AC,Barroso JG and Deans SG,In vitro evalu-ation of antioxidant activity of essential oils and their components.

Flav Fragr J15:12–16(2000).

8Lazarevi JS,Dordevi AS,Zlatkovi BK,Radulovic NS and Palic RM, Chemical composition and antioxidant and antimicrobial activities of essential oil of Allium sphaerocephalon L.subsp.sphaerocephalon (Liliaceae)in?orescences.J Sci Food Agric91:322–329(2011).

9Murphy A,Kerry JP,Buckley J and Gray I,The antioxidative properties of rosemary oleoresin and inhibition of o?-?avours in precooked roast beef slices.J Sci Food Agric77:235–243(1998).

10Radhakrishnan K,Sivarajan M,Babuskin S,Archana G,Saravana Babu PA and Sukumar M,Kinetic modeling of spice extraction from S.

aromaticum and C.cassia.J Food Eng117:326–332(2013).

11Viuda-Martos M,El Gendy AE-NGS,Sendra E,Fernández-López J,Abd El Razik KA,Omer EA et al.,Chemical composition and antioxidant and anti-Listeria activities of essential oils obtained from some Egyptian plants.J Agric Food Chem58:9063–9070(2010).

12Hygreeva D,Pandey MC and Radhakrishna K,Potential applications of plant based derivatives as fat replacers,antioxidants and antimi-crobials in fresh and processed meat products.Meat Sci98:47–57 (2014).

13Radhakrishnan K,Babuskin S,Saravana Babu PA,Fayidh MA,Sabina K,Archana G et al.,Bio protection and preservation of raw beef meat using pungent aromatic plant substances.J Sci Food.Agric 94:2456–2463(2014).

14AOAC,O?cial Methods of Analysis.Association of O?cial Analytical Chemists,Gaithersburg,MD(1995).

15Bigolin J,Weber CI and Alfaro AT,Lipid oxidation in mechanically deboned chicken meat:e?ect of the addition of di?erent agents.

Food Nutr Sci4:219–223(2013).

16Barbosa-Pereira L,Aurrekoetxea GP,Angulo I,Paseiro-Losada P and Cruz JM,Development of new active packaging?lms wrapped with natural phenolic compounds to improve the oxidative stability of beef.Meat Sci97:249–254(2014).17Oliver CN,Ahn BW,Moerman EJ,Goldstein S and Stadtman ER,Age-related changes in oxidized proteins.J Biol Chem 262:5488–5491(1987).

18Conway EJ,Micro-di?usion Analysis and Volumetric Error.Van Nostrand, New York,NY(1947).

19Chandra mohan C,Rakhavan KR,Sudharsan K,Radha krishnan K, Babuskin S,Sukumar M,Design and characterization of spice fused tamarind starch edible packaging?lms.LWT-Food Sci Technol.

DOI:10.1016/j.lwt.2016.01.004(2016).

20Zhou K and Yu L,Total phenolic contents and antioxidant properties of commonly consumed vegetables grown in Colorado.LWT–Food Sci Technol39:1155–1162(2006).

21Gill AO and Holley RA,Disruption of Escherichia coli,Listeria monocy-togenes and Lactobacillus sakei cellular membranes by plant oil aro-matics.Int J Food Microbiol108:1–9(2006).

22Gill AO and Holley RA,Mechanisms of bactericidal action of cin-namaldehyde against Listeria monocytogenes and of eugenol against L.monocytogenes and Lactobacillus sakei.Appl Environ Microbiol70:5750–5755(2004).

23Wendakoon CN and Sakaguchi M,Inhibition of amino acid decar-boxylase activity of Enterobacter aerogenes by active components of spices.J Food Protect58:280–283(1995).

24Suresh P,Ingle VK and Vijayalakshima V,Antibacterial activity of eugenol in comparison with other antibiotics.J Food Sci Technol 29:254–256(1992).

25Gupta C,Garg AP,Uniyal RC and Kumari A,Comparative analysis of the antimicrobial activity of cinnamon oil and cinnamon extract on some food-borne microbes.Afr J Microbiol Res2(9):247–251(2008). 26Mastromatteo M,Danza A,Conte A,Muratore G and Del Nobile MA, Shelf life of ready to use peeled shrimps as a?ected by thymol essen-tial oil and modi?ed atmosphere packaging.Int J Food Microbiol 144:250–256(2010).

27Nirmal NP and Benjakul S,E?ect of catechin and ferulic acid on melanosis and quality of Paci?c white shrimp subjected to prior freeze–thawing during refrigerated storage.Food Control 21:1263–1271(2010).

28Ludor?W and Meyer V,Fische und Fischerzeugnisse.Verlag Paul Parey, Hamburg(1973).

29Bak LS,Andersen AB,Andersen EM and Bertelsen G,E?ect of modi?ed atmosphere packaging on oxidative changes in frozen stored cold water shrimp(Pandalus borealis).Food Chem64:169–175(1999). 30Koka R and Weimer BC,In?uence of growth conditions on heat-stable phospholipase activity in Pseudomonas.J Dairy Res68:109–116 (2001).

31Okpala COR,Choo WS and Dykes GA,Quality and shelf life assessment of Paci?c white shrimp(Litopenaeus vannamei)freshly harvested and stored on ice.LWT–Food Sci Technol55:110–116(2014).

32Huang J,Chen Q,Qiu M and Li S,Chitosan-based edible coatings for quality preservation of postharvest whiteleg shrimp(Litopenaeus vannamei).J Food Sci77:491–496(2012).

33Lannelongue M,Finne G,Hanna MO,Nickelson R and Vanderzant G, Storage characteristics of brown shrimp(Penaeus aztecus)stored in retail packages containing CO2-enriched atmospheres.J Food Sci 47:911–914(1982).

34Fatima R,Khan MA and Qadri RB,Shelf-life of shrimp(Penaeus mer-guiensis)stored in ice(0°C)and partially frozen(?3°C).J Sci Food Agric42:235–247(1988).

35Cadun A,Cakli S and Kisla D,A study of marination of deepwater pink shrimp(Parapenaeus longirostris,Lucas,1846)and its shelf life.Food Chem90:53–59(2005).

36Lu S,E?ects of bactericides and modi?ed atmosphere packaging on shelf-life of Chinese shrimp(Fenneropenaeus chinensis).LWT–Food Sci Technol42:286–291(2009).

37Mejlholm O,B?kn?s N and Dalgaard P,Shelf life and safety aspects of chilled cooked and peeled shrimps(Pandalus borealis)in modi?ed atmosphere packaging.J Appl Microbiol99:66–76(2005).

38Gram L and Dalgaard P,Fish spoilage bacteria–problems and solu-tions.Curr Opin Biotechnol13:262–266(2002).

39Gram L and Huss HH,Microbiological spoilage of?sh and?sh products.

Int J Food Microbiol33:121–137(1996).

40Fall PA,Leroi F,Cardinal M,Chevalier F and Pilet MF,Inhibition of Brochothrix thermosphacta and sensory improvement of tropical peeled cooked shrimp by Lactococcus piscium CNCM I-4031.Lett Appl Microbiol50:357–361(2010).

https://www.360docs.net/doc/4e13888456.html,/jsfa?2016Society of Chemical Industry J Sci Food Agric(2016)