Physical and mechanical features investigation of protein-based biodegradable films obtained from trout fish waste

Transcription

1 Journl of Food nd Bioprocss Enginring (JFBE) 49-6 ORIGINAL ARTICLE Physicl nd mchnicl fturs invstigtion of protin-bsd biodgrdbl films obtind from trout fish wst Mrziy Mirzkhni*, Sohrb Moini, Zhr Emm-Djomh Rcivd: 10 April 015 / Accptd: 1 August 015 Abstrct Biologicl pckging mtril bsd on obtind protins from fish wst, r biopolymrs tht hv th cpbility of biodgrdbl film formtion. Thus, purpos of this rsrch is to study nd invstigt som of films physicl fturs md from trout fish Myofibril protin. Th film forming solution contining %, % nd.5%(w/v)myofibril protin isolt of 100ml solution nd glycrol s plsticizr in thr lvls 5%, 50%, 75%(w/w) pr dry mtril hv bn usd. In ordr to solv xisting protin in solution its ph must b rch to 3 by 1molr HCl. Films hv bn producd by csting mthod for 48 hours in 5 c. Thn film s mchnicl fturs, wtr vpor pntrbility, films solubility in wtr, trnsprncy nd color wr invstigtd. Effct of protin concntrtion ws significntly obvious on films mchnicl fturs, thicknss, wtr vpor pntrbility nd color. Obtind rsults from sttisticl nlysis dt by spss softwr showd tht films with %(w/v) dry mtril long with 50%(w/w) glycrol dmonstrtd th bst mchnicl fturs. Kywords: Trout fish wst; Edibl film; Mchnicl proprtis; Wtr vpor prmbility, Scnning lctron microscop Introduction Mtril usd for pckging, r biologicl contminnt. Plstic with oil rsourc lik polyolphins, polystr snd polymids du to vilbility in lrg mount nd rsonbl pric nd sufficint functionl chrctrs r usd widly s pckging mtril, howvr ths compounds r not biodgrdbl nd cus nvironmntl pollution (Thrnthn 003). Films nd dibl cotings r in th form of dibl thin lyrs which put on food surfc or insid of its constitunts nd r dtrmind s on of bsic strtgis to control th physiologicl, microbil nd physiochmicl chngs in food. Thir min structur is bsd on nturl polymrs hving spcific chrctrs nd th min constitunts of films nd dibl cotings includ: lipids, protins nd polyscchrids (Krocht 00). Rcntly rng of studis ccomplishd on nd bout dibl films nd cotings bsd on polyscchrids, lipids, protin or combintion of thm with following dvntgs: dgrdbility in ntur, slctiv pntrbility nd possibility of vpor trnsfrring control, oxygn nd Co trnsmission control, using dibl films nd cotings s thir potntil bility to provid combintion of moistur, oxygn, tst, smll, color nd dibl oil inhibitory fturs long with thir qulity nd shlf lif of food incrs. In mny css, th most importnt fturs of film with dibl cots r fighting ginst moistur trnsfr. Bcus spcific lvls of wtr ctivity should b prsrvd in lot of foods, dstructiv nzyms nd chmicl rctions r grtly undr th ffct of wtr ctivity or mount of moistur. Moistur trnsfr spd btwn food nd surrounding tmosphr dcrss by complt covring of food using dibl film or coting. In ddition to vpor M, Mirzkhni*( )., S, Moini,. Z, Emm-Djomh Trnsfr Phnomn Lbortory (TPL), Dprtmnt of Food Scinc, Tchnology nd Enginring, Fculty of Biosystms Enginring, Univrsity of Thrn E -mil ddrss: m_mirzkhni@ut.c.ir

2 Journl of Food nd Bioprocss Enginring (JFBE) 50 trnsfr, trnsfr of som gs lik oxygn nd CO ffcts th food shlf lif(sircus t l. 008). Gnrlly, mchnicl nd inhibitory fturs of protin-bsd films r widly from polyscchrids films. Bcus unlik polyscchrids which r homopolymr, protins hv prticulr structur (bsd on 0 typs vrious Amino cids) tht cuss vst rngs of potntil functionl chrctrs of ths films, spcilly incrs of molculr bonds. Thy r bl to stblish plnty of diffrnt bond typs nd vrious nrgy tht provid solubility conditions nd ph in diffrnt r of protin bonds s function of tmprtur. According to th obtind rsult from Kinsll (1976), Chou nd Morr (1979), nd Chftl t l (1985) studis, xprimntl prmtrs lik protin concntrtion, ph, tmprtur, tim, ionic strngth, nd diffrnt dditiv prcnt, cuss th chng of protin-protin nd protinwtr rctiv powr tht lds to chng of functionl fturs. Effcts of ths prmtrs on Myofibril gl forming fturs nd film formtion hv bn studid by Lvll nd Fogding (1993) Wu nd Bts (197) rspctivly. Furthrmor, in ordr to improv thir fturs, rw protin mtril cn b chngd chmiclly (Osw nd Wlsh 1993). Protins with high molculr wight r gnrlly insolubl or poorly solubl in wtr, so thr r molculs which r vry intrstd in wtr rsistnt film forming. Among ths protins, myofibril protins r bl to form unusul films. Myofibril protins mk up mor thn 50% of muscl wight. Thy includs contrctibl protins (ctin nd myosin) nd rgulting muscls contrction protins (tropomyosin, troponin, ctin, ) which cn b idntifid through thir unusul fturs. Formtion of protin films rquirs complt solution of protin by rgulting ph of film forming solution using pproprit solubl (Thrgorbi t l. 01). Purpos of this rsrch is to invstigt th mchnicl, opticl, WVP nd solubility fturs of films md of trout fish myofibril protin. Mtrils nd mthods Mtril Glycrol with 98% purity from Acros compny (Englnd) usd in ll formultion s plsticizr. In ordr to solv th myofibril protins, sodium hydroxid (NOH) 97% purity nd chloridric cid (HCL) 37% purity bought from Mrk Compny (Grmny). To produc rltiv humidity 53% Mgnsium sulft nd clcium chlorid (Clcium chlorid dhydrt) to rgult th ctivity of wtr (w) in 0.75 providd from Mrk compny (Grmny) nd sodium zid to inhibit th microorgnism growth hv bn usd. Fish smpl Th frm frsh trout with vrg wight of g pproximt lngth of 18-9cm bought from locl mrkt. Fish hv bn put in ic in rtio of1:(fish/ic) nd ftr 30min t th mximum ws snd to th lbortory. Thn smpl prprtion stgs hv bn don immditly. Smpl prprtion nd protin rcycl A trout (including skin, scl nd bon) usd to rcycl th muscl protin isolt by solubility/prcipittion procss dscribd by Nolso nd Undlnd 009 in Fig 1. protin solution xisting in wtr nd ffctd by mixd ph(nolsø nd Undlnd 009). Firstly, fish mincd by mt grindr (ModlMT-1000 Prs TOSHIBA industril co/irn) with 4.95mm msh thr tims. Smpl mixd with cold ionizd stilld wtr in rtio of 1:9 nd mixd by mixr (Sunny.modl:SFP-80/Irn) 80W for 1 minut. During th procss, smpl tmprtur modifid by bing put in ic 4 c(thrgorbi t l. 01). Prprd smpl

3 51 Volum 1, No., Summr 015, 49-6 homognizd by ultrtorx homognizr (IKA- T5 digitl)10000 round pr minut for 1 min. Scondly, myofibril nd skltl protin with modifying mixd ph solvd in ph= Undr ths condition ll th srcoplsmic protins solvd nd unsolvd prts r only prts of connctiv tissu protins, mmbrnous protin, nd probbly dnturd srcoplsmic nd myofibril protin. In th third stg solubl prt sprtd from insolubl prt by cntrifug 10000g round in 4 c for 10min. Thn in th fourth stg by rrnging ph in isolctric point myofibril protin prcipitt in ph= using NoH 1 molr nd in th lst stg protin sdimnt sprtd by cntrifug 10000g round in 4 c for10 min(nolsø nd Undlnd 009). Homogniztion Mincd fish/ wtr (w/v) 1:19 Solubility in Isolctric point PH= or PH= Sprting of solubl contnt from nonsolubl mtril with cntrifug 10000g for 10 min in 4C Uppr lyr Fish oil Middl lyr Fish protin solution Lowr lyr Non-solubl mtril (bon, skin, nonsolubl protins, mmbrn lipids, ) Protin prcipittion t isolctric point by 1 molr NOH Rtrivl of solution s prcipittd protin by cntrifug 10000*g for 10 min in 4C Fig 1. Rtrivl of fish isoltd protin using solubility/ prcipittion t isolctric point

4 Journl of Food nd Bioprocss Enginring (JFBE) 5 Film solution prprtion To prpr film from thr concntrtions 1. 5%(w/v), %,.5% of dry mtril long with plsticizr in concntrtion 5%(w/w of protin), 50% nd 75% wr usd. Th solution of film prprtion dvlopd by Pscholick nd collgus(pscholick t l. 003). So th forming solution compound includs: %, %,.5%(w/v) protin dry mtril (grm pr 100ml film forming solution), glycrol s plsticizr in thr lvls.5%, 50%, 75% (w/v) (grm glycrol to grm protin) hv bn usd. Th ph solution rgultd using chloridric cid (1molr) rchd th point 3. Thn th film solution ws pourd in Tflon plt nd in n ntir blncd lvl to obtin films with homognous surfc hving idnticl thicknss in ll prts, put in n 30 C incubtor fn quippd (to mov th ir) for 48 hours. Thicknss Thicknss of unconditionl films using digitl Micromtr (Mitutoyo,LIC.No Jpn) with prcision 0/0001mm in 5 diffrnt points (4 in circumfrnc nd 1 in cntr) of films msurd in rndom nd wr vrgd. Moistur contnt Pics of totlly homognous films ftr rriving to quilibrium moistur wighd by digitl scl with prcision nd plcd insid cpsul tht rchd constnt wight in dvnc. Thn to rch constnt tmprtur is put in 105 c for 4 hours. In this tst glycrol vportion from film considrd ngligibl. Thn ccording to th smpls wight rduction in compr to initil smpl, film moistur prcnt idntifid. This tst rptd 5 tims nd th obtind dt mn rportd s th film moistur. Solubility in wtr Solubility in wtr of dibl films dtrmind by Gontrd nd collgus mthod(gontrd 1994). Aftr dtrmintion of film moistur vlu, contnt of xisting solid mtril wr idntifibl. According to it, following th film rchs th quilibrium moistur nd drying in 105 C ovn for 4h, wr htd to pproch constnt wight nd msurd ftr drying.thn film pics wr put in 50cc distilld wtr nd to prvnt microorgnism growth 0.0 (w/v) zid sodium ws ddd. Thn th smpl continr ws put in 5 C for 4h undr slow stirring condition, th mixtur of film nd wtr filtrd on filtr ppr which prviously rchd th constnt wight nd msurd. Filtr ppr long with smpls plcd in constnt tmprtur of 105 c to rch constnt wight. Wtr vpor prmbility Pntrbility msurmnt tst ccomplishd using th modifid ASTM mthod No E96. To prform th prsnt tst wtrlss clcium chlorid pourd insid th glss cll. Thn th cll s surfc covrd by mltd prffin. In this cs 0% rltiv moistur xists in clls. Clls wr plcd in dsicctor contining sturtd NCl. Sturtd NCl producd 75% moistur in 5 c. Diffrncs in moistur on both sids of film rcordd by digitl scl with 0/0001 ccurcy nd in ll smpls by drwing th grph of wight chngs to tim, grph drwn in th function tim form. Slop of ch drwn lin figurd by rgrssion lin (R=0/999) nd rt of vpor trnsfr obtind by dividing th drwn slop lin (gs -1 ) into film s surfc (m ). WVP obtind by multiplying th film thicknss nd dividing to prssur diffrncs btwn cll nd dsicctor s rltiv moistur. Mchnicl proprtis Film mchnicl tsts ccomplishd using Tstomtr quipmnt (Rochdl, Lnchshir, Englnd, M350-10ct,Tstomtric Co,Ltd). Films wr cut rctngulr siz of 10mm * 100mm, ccording to stndrd mthod nd du to low thicknss of smpls nd

5 53 Volum 1, No., Summr 015, 49-6 smllnss of quipmnt jw, thr ws no nd to us dumbbll -shpd smpls. Using stndrd mthod of ASTM(D88 Stndrd Tst Mthod for Tnsil Proprtis of Thin Plstic Phildlphi: Amrcin Socity for Tsting nd Mtrils,) th spc btwn th quipmnt s jws fixd 50%. Smpls plcd in 5 c nd 50% rltiv moistur by Mgnsium Nitrt sturtd solution usd for smpl s conditioning. Tnsil strngth (TS) fctors nd longtion t brk (EAB%) obtind from Strss- Strin grphs. Rptd 5 tims for ch smpls. color In ordr to idntify th film color colorimtr Minolt modl (Minolt,CR 300 Sris, Minolt cmr Co, Ltd,Osk, Jpn) usd to msur L, b nd prmtrs. Prior to th film color msurmnt quipmnt fixd using n stndrd whit plt s plts with smpls on it nd th color stndrd prmtrs idntifid s (L=84.71,=+1.6,b=-3.58). Smpls plcd on stndrd whit plt nd th bov prmtrs hv bn msurd. Prmtrs tht is showd by th quipmnt r: Light (0=blck nd 100=whit) nd colorful prmtrs (+60=rdnss to -60=grnnss) nd b (+60=yllownss to -60= blunss). Thr points slctd in rndom for ch film. Trnsprncy Trnsprncy msurd using Luxomtr (Tsto 540 pockt sizd, UK). To do th prsnt tst initilly th quipmnt bubbl put undr light sourc with minimum modultion nd th rt of crossing light notd ccording to th obtind lux nd from two chivd numbrs, th smpls trnsprncy rportd in prcnt. At lst 5 rptition considrd for tst of ch film Study of morphology by scnning lctron microscop (SEM) Elctron microscop imgs of film surfc nd cross sction providd in ordr to invstigt th ffct of glycrol ddition s plsticizr on producd film structur. To study th film s morphology md of fish myofibril protin long with plsticizr th scnning lctron microscop (Philips XL 30, Nthrlnds) hving img nlysis systm with cclrtion voltg of 15 kv hv bn usd. Prior to smpl imging, films wr cut in siz of 5mm x1mm by surgicl bld, instlld on bronz plt nd covrd by lyr of gold in ordr to conduct th smpls, nd imging don by nlrging 500 for surfc nd 800 for cross sction of film. Sttisticl nlysis Sttisticl clcultion dtrmind ccording to fctoril tst in complt in rndom formt by using vrinc nlysis (ANOVA) in 5% probbility lvl. Comprison of dt mn using spss softwr vrsion 17 bsd on Dunkn tst ccomplishd. Rsults nd discussion Thicknss Existing dry mtril contnt in film surfc unit, fitting th dvlopd film s pprnt thicknss dirctly is from fish myofibril protin. It sms tht ordr of chins which forms th protin mtrix is kind tht stblishs constnt dnsity, vn in css tht drying of film forming solution tks longr tim thn usul. As th films protin contnts incrss, du to polr groups tht xist in protin s surfc, It is cpbl to bsorb th surrounding wtr. So through incrs of protin dry mtril from % (w/v) to.5% (w/v) thicknss incrss significntly (p>0.05) (Tbl 1). Effct of thicknss chngs on dibl film mchnicl nd physicl fturs is considrbl. Obtind rsults from vrious dt show tht by incrs of protin dry mtril contnt from % (w/v) to.5% (w/v) films thicknss lso incrss from stimtd vlus 0.05mm, 0.059mm nd 0.069mm

6 Journl of Food nd Bioprocss Enginring (JFBE) 54 rspctivly for %, % nd.5%(w/v) (p<0.05). Along with thicknss incrs, rquird powr for tring of films hs lso dmonstrtd significnt incrs (Tbl 1). Trnsprncy Considring th ppliction of dibl films, trnsprncy is proposd s on of th fundmntl fctors of dibl film ccptnc(fng 006). Th obtind films from myofibril protin r trnsprnt nough to b usd in pckging systm. Howvr, trnsprncy msurmnt nd its comprison with color indx shows tht fish myofibril protin films in low concntrtion of dry mtril %(w/v) r givn high trnsprncy (83.8) tht dcrss (36.%) through th incrs of dry mtril concntrtion.5%(w/v) nd th light nd trnsprnt color of films tnd towrds yllownss nd th incrs of b prmtr (Tbl ) confirms this pprnt chng. Solubility in wtr Totlly, dding of plsticizr to polymr mtril cuss th chng of thr-dimnsionl molcul structur, dcrs of molculr grvity nd incrs of fr volum nd molcul chins mobility (Ekrmi nd Emm Djomh 014). Solubility in wtr incrs of films, contining plsticizr, is th rflction of plsticizr solubility in wtr. Th protin ntwork solubility in wtr is not undr th significnt influnc of plsticizr concntrtion. In othr words, dding plsticizr to th myofibril protin-bsd films cuss grt rduction in film strngth nd tnsil nd lso significnt incrs of trnsformtion nd WVP fturs. Diffrnc in film solubility dpnds on thir thicknss. Tbl 1. Trout myofibril protin films solubility, thicknss nd trnsprncy in vrious dry mtril concntrtions Protin Glycrol Solubility Trnsprncy concntrtion concntrtion thicknss(mm) (%) (%) )w/v( )w/w( 5 f 0.041±0.015 f 11.3±0.46 b 96.57± df 0.049± ±0.39 b 97.08± bcd 0.059±0.006 c 19.88± ±0. 5 cd 0.046± ±0.37 d 94.79± f 0.056±0.003 d 16.36±0.36 d 95.07± bc 0.061±0.009 c 19.9±0.64 bc 96.16± b 0.066±0.016 c 19.49± ± bc 0.069±0.007 b.09±0. d 94.67± ± ±0.75 cd 95.4±0.16 Th vrg in ch column with diffrnt English lttrs hv significnt diffrnc (p<0.05) dt includ mn + stndrd dvition Rgrdlss th typ nd concntrtion of plsticizr, myofibril protin won t sprd in wtr ftr 4h nd rmins untouchd in wtr. Incrs in contnd of utilizd plsticizr (rgrdlss of its typ), incrs th contnt of solubl dry mtril in wtr nd cuss th linr incrs in solubl dry mtril contnts. In fct it is th ffct of hydrophilic plsticizr contnts chng tht cuss th incrs of protin film solubility in wtr. Mchnicl proprtis Through incrs of dry mtril from % (w/v) to %(w/v) in pr films surfc unit, th smpls tnsil strngth vlu incrss from.86x10-11 to 3.84 x Biologicl pckging bsd on fish myofibril protin, hv th similr mchnicl fturs to othr biologicl-bsd pckging. Mchnicl fturs of biologicl pckging bsd on trout myofibril protin r vry clos to physicl fturs of polyscchrid

7 EAB (%) TS (MP) 55 Volum 1, No., Summr 015, 49-6 films lik tnsil nd brking point for propyl Mthyl cllulos-bsd films nd tnsil. strngth for hydroxyl propyl mthyl cllulosbsd films(cuq t l. 1995) b c d g f g Glycrol (%) Fig. Effct of vrious dry mtril nd glycrol on tnsil strngth (TS) of trout myofibril protin films On th othr hnd myofibril protin rltivly contins normous contnt of Glutmin nd sprgin Amino cid (10mol/100mol mino cid). Rplcmnt of doubl hydrogn bonds (85kj/mol) btwn two mid groups, with singl hydrogn bonds (5kj/mol) btwn n mid group nd plsticizr molcul cn lso b nothr rson for molculr rction dnsity dcrs in ths films g b b c d f h Glycrol (%) Fig 3. Effct of vrious dry mtril nd glycrol on longtion t brk (%EAB) of trout myofibril protin films Wtr vpor prmbility (WVP) Bcus of high hydrophilic groups in polymr chins, protin nd crbohydrt dibl films hv low inhibition of wtr vpor, in protins s non-polr Amino cid (Hydrophobic) is high in

8 WVP (g/smp) ) Journl of Food nd Bioprocss Enginring (JFBE) 56 compr to polr Amino cid in thir structur, inhibition will b mor. As it is xpctd, through plsticizr concntrtion incrs, normous incrs obsrvs in WVP. Plcmnt nd connction of plsticizr insid mtrix polymr ntworks cuss chng in polymr cohsiv ntwork construction so tht cuss th fr spc btwn polymr chins, thus polymr mtrix hs low dnsity nd s rsult it will b mor pntrbl. Considring th obtind imgs from th films cross sction it is rlizd tht in high dry mtril concntrtion, du to lck of dhsion in protin mtrix, xisting crcks, th WVP incrss. Considr th fig 4 dt, in proportion to dry mtril, dt sttisticl nlysis, shows WVP significnt incrs (p<0.05). Pntrbility rsultd from plsticizr concntrtion incrs is du to plsticizr molcul hydrophilic ftur. In fish myofibril protin-bsd films positiv cohsion xists btwn thicknss nd WVP, though this rltionship dos not xist in idl polymr-bsd films, bcus for idl homognous polymr, PHIC lw rquirs th chng of vpor lkg undr vpor prssur grdint invrsly by th film s thicknss (Husr 1948). So, bcus of dry mtril contnt incrs from %(w/v) to.5%(w/v) which ccompnis th film thicknss incrs nd lso du to incrs of hydrophilic groups incrs nd lck of pproprit solubility nd film s homognity, WVP incrss significntly (p<0.05). 5 0 b c d g f h Glycrol (%).5 Fig 4. Effct of vrious dry mtril nd glycrol on wtr vpor prmbility (WVP) on trout myofibril protins Color Rgrdlss of th typ nd concntrtion of plsticizr, producd films from fish myofibril protin, r trnsprnt nd colorlss. Glycrol concntrtion incrs cuss th rduction of film s color tht is probbly s th rsult of glycrol lution which is n indpndnt nd colorlss mtril of protin concntrtion(do A Sobrl t l. 005). Considring tht solving protin in cidic condition hppns with ph=3, it is obsrvd tht cidic condition, stimult th formtion of yllow pigmnts, prticulrly thos which r producd during Milrd rctions(chinbhrk t l. 007). As th protin concntrtion incrss mor, it cuss th incrs of b prmtr nd dcrs of prmtr.

9 57 Volum 1, No., Summr 015, 49-6 Tbl. color prmtr including L, nd b of trout myofibril protin films in dry mtril nd glycrol vrious concntrtions Protin concntrtion )w/v( Glycrol concntrtion )w/w( Th vrg in ch column with diffrnt English lttrs hv significnt diffrnc (p<0.05) dt includ mn + stndrd dvition b -.66±0.1 bcd -.77±0.43 cd -.8±0.61 d -1.9±0.19 b -1.99±0.34 b -.06±0.65 bc -1.41± ±0.40 -± ±0.09 b 0.8±0.16 b 0.83± ±0.06 bc 0.67±0.05 bc 0.69±0.09 bc 0.50±0.01 c 0.5±0.14 c 0.57±0.04 bc L 70.7± ± ± ± ± ± ± ± ±6.1 Study of morphology by scnning lctron microscop Study of morphologicl fturs in polymrs is n importnt fctor to undrstnd its bhvior nd fturs(frinult 006). Tkn imgs of SEM from film s surfc (50% (w/w) glycrol) giv th bnficil dt from th film s morphology, surfc nd cross sction. Imgs obtind from fish myofibril protinbsd films (Fig 5 nd 6) dmonstrts homognizd structur in which gthring of myofibril protins forms dns nd consistnt ntwork which is lso confirmd in othr rsrchs (Limpn 010). Though, prsnc of dns mtrix is on of common fturs of protin films, incrs of dry mtril contnt, dditionl protin tht r not bl to b solvd in film forming solution r obvious in th form of insolubl llips-lik clustrs in cross sction imgs (Fig 7).Through incrs of th film s dry mtril from %(w/v) to.5%(w/v) solubility dcrss nd this lck of solubility cuss th dcrs of film s dhsion nd incrs of WVP (Fig 4) tht bhvior is obsrvd in similr films which r producd from myofibril protins of othr fish (Sobrl 007). c b Fig 5. Scnning lctron microscop (SEM) from th surfc r (front surfc) (%w/v + %50Glycrol w/w, ), (%w/v + %50Glycrol w/w, b), (%.5w/v + %50Glycrol w/w, c) Trout myofibril protin films f d

10 Journl of Food nd Bioprocss Enginring (JFBE) 58 Fig 6. Scnning lctron microscop from th bck surfc (%w/v + %50Glycrol w/w, d), (%w/v + %50Glycrol w/w,, (%.5w/v + %50Glycrol w/w, f) Trout myofibril protin films i h g Fig 7. Scnning lctron microscop cross sction (% w/v + %50Glycrol w/w, g), (%w/v + %50Glycrol w/w, h), (%.5w/v + %50Glycrol w/w, i) Trout myofibril protin films Discussion For mcromolculr ntwork nd frqunt rction typs, ths chngs cn b s incrs in numbrs of protin bonds pr surfc unit tht lds to incrs of intrmolculr rctions numbrs. By thicknss incrs s th rsult of dns chins of mtrix polymr nd dcrs of spc btwn chins for wtr molculs crossing, gnrlly WVP should incrs but in protin films du to incrs of polr nd hydrophilic groups on surfc, ffct of chins dnsity incrs on WVP dcrs is not significnt nd it will incrs bcus of thicknss incrs. Invstigtion into ffct of glycrol concntrtion on protin film thicknss of fish showd tht by incrsing of glycrol contnt in ll dry mtril contnt, thicknss incrss significntly (p<00.05) (Tbl 1). Bcus of hydrophilic ntur of glycrol from 5%(w/v) to 75%(w/w) moistur vlu incrss nd polymr mtrix chins sty in furthr intrvl so th smpls swlling nd thicknss incrss s wll (Tbl 1). Th ffct of glycrol on thicknss of othr dibl films dmonstrts th similr rsult. Also, du to disbility of nturl light to cross through th compct crystl structur, xistnc of crystl r in mtril cuss its opcity, this incrs of solid mtril from %(w/v) to.5%(w/v) cuss th significnt dcrs in films trnsprncy (p<0.05). Although th glycrol contnt in this rsrch didn t influnc th trnsprncy vlu (p>0.05), in othr

11 59 Volum 1, No., Summr 015, 49-6 rsrchs ccording to structur nd ntur of dibl film, glycrol ddition cuss th incrs (Mu 01) or dcrs (Zhng 006) of dibl film s trnsprncy vlu. Rgrdlss th typ nd concntrtion of plsticizr, myofibril protin won t sprd in wtr ftr 4h nd rmins untouchd in wtr. Incrs in contnd of utilizd plsticizr (rgrdlss of its typ), incrs th contnt of solubl dry mtril in wtr nd cuss th linr incrs in solubl dry mtril contnts. In fct it is th ffct of hydrophilic plsticizr contnts chng tht cuss th incrs of protin film solubility in wtr. Chng in non-protin dry mtril contnt (in othr words) in film s function of plsticizr concntrtion cuss chng in fish dry mtril solution contnts in wtr. On th othr hnd du to formtion of low wight protin smll chins (such s monomrs nd smll pptid) during th film forming solution prsrvtion nd bing plcd in protin mtrix could form solubl mtril in wtr (CUQ t l. 1995). So, long with th incrs of protin contnt from to.5%, th smpl s solubility in wtr incrss s wll (Cuq 1997). On th whol, plsticizr forms lrg proportion of solubl dry mtril in wtr. On th othr hnd, protin ntwork won t sprd or solv in wtr. Corrsponding ffct of high dnsity nd crtin prsnc of intrmolculr covlnc bonds or physicl tis (chins intrction) prtilly is th rson of th film s insolubility. This bhvior of solubility in wtr cn t b gnrlizd nd undrstnding of film solubility in wtr is so complictd. Probbly high solubility of films cn b xplind by poor structur of films which contins lss TS nd mor EAB. Gnrlly, long with glycrol concntrtion incrs, obsrvtion of tnsil strngth vlu nd th lngth incrs in brking point is common bhvior in cs of protin-bsd nd incrs of tnsil ftur ( trnsformtion in brking point). films(do A Sobrl t l. 005). Film s tnsil strngth which is dpndnt to its thicknss hs bn studid by Gndios to compr th film fturs with vrious thicknss nd diffrnt rctions (lik plsticizr ddition) (Gnndios 00). Mhmood nd Svlov lso suggstd tht powr t th tim of why protin-bsd film s brkg, dpnds on film thicknss nd plsticizr concntrtion. Obtind film from fish myofibril protin lik othr protin film without dding softnr r crispy nd frgil nd hv poor nd limitd functionl fturs. Film from myofibril protin without plsticizr compr to films tht contins plsticizr, shows diffrnt mchnicl bhvior. Considring th obtind rsults from initil studis myofibril protins rich in non-ioniz polr Amino cids (7mol/100mol mino cid) tht r bl to form normous hydrogn protin-protin bonds which cuss low dhsion nd flxibility of film without plsticizr. Glycrol is hydrophilic molcul with low molculr wight tht cn sily connct th protin chins nd stblishs hydrogn bond with xisting rctiv group. Whn protin nd plsticizr stys bsid ch othr, stimult th crtion of plsticizr-protin rctions tht cuss th dstruction of protin-protin rctions.as th rsult intrmolculr rction dnsity dcrss nd fr spc btwn polymr chins will incrs. Whn th blnk films (without plsticizr) r chngd, prssur incrss continully until th smpl brks. Thus, ths films r frgil mtrils with tnsil ftur 0.15mm nd high mchnicl strngth 5.1N. Whn plsticizr is ddd to th smpl, xprimntl non-linr grph, dmonstrts th viscolstic bhvior of ths films. In ddition, by plsticizr concntrtion incrs from 5% (w/w) to 50% (w/w), w obsrv th dcrs of mchnicl strngth Bcus of th smll siz of glycrol concntrtion, plcmnt insid th mtrix nd

12 Journl of Food nd Bioprocss Enginring (JFBE) 60 rction with polymr ntwork is sily possibl. Thus s glycrol concntrtion incrss (75%(w/w) to 50%(w/w) numbrs of glycrol molcul in film surfc unit tht plc btwn protin chins, incrss, s th rsult dnsity of intrmolculr rctions dcrss, ffctiv connction btwn protin chins is low nd fr spcs of polymr chin dcrss. All of ths rsons togthr cus tht long glycrol concntrtion mchnicl strngth vlu rducs nd lstic fturs of film incrss. Incrs in th numbr of intrmolculr rctions which is rltd to th film thicknss, hs no significnt influnc on lngth incrs up to th film brking, nd hs poor influnc on viscolstic fturs of this kind of films. In contrry to prssur in tim of brking, thicknss incrs dosn t hv significnt influnc on tnsil incrs chngs in brking point (CUQ 006). Plsticizrs r considrd s mtrils tht du to glycrol concntrtion incrs nd contining hydrophilic polr groups, cuss th bsorption of xisting wtr in circumstnc nd incrs of film s finl humidity nd dcrs of protin-protin rctions which lds to incrs of protin chin s movmnt.this rson, lso cuss th lss rsistnc nd mor Hmolsticity of protin films nd in proportion to incrs of glycrol concntrtion from 5%(w/w) to 75%(w/w) vlu of wtr vpor pntrbility incrss (do A Sobrl t l. 005). In protin films, through incrs of protin concntrtion in film forming solution, bcus of hydrophilic groups incrs, vlu of wtr bsorption from surrounding circumstnc incrss which shows its ffct in finl film thicknss (Tbl 1). Incrs of hydrophilic groups lds to chins mobility in polymr mtrix nd s rsult rt of wtr tndncy % (w/v) to.5% (w/v), bcus initil mtril prticipnt in Milrd rction incrss, yllownss will b mor nd lightnss incrss nd WVP will incrs (Tbl). To form propr film, th film forming solution should b ntirly homognizd nd contins low viscosity. By incrs of protin concntrtion from % (w/v) to.5% (w/v) th film forming solution sprding on plt hrdly hppns nd th finl film dnsity rducs. Elctron microscop imgs shows th crck formtion nd hols incrs which is th rsult of film dnsity rduction long with incrs of film forming dry mtril tht cuss th WVP incrs du to protin concntrtion in th film forming solution. Effct of glycrol concntrtion incrs on dibl film pntrbility from primry rsourc is invstigtd in othr similr rsrch nd sm rsults r obtind. Glycrol is hydrophilic micro molculr softnr tht cuss th dcrs of grvity nd incrs of mobility btwn polymr chins,morovr by incrs of glycrol du to polr groups numbr incrs (OH) hydrogn bonds formtion bility with wtr incrss nd in turn cuss th WVP incrss(chinbhrk t l. 007; CUQ t l. 1995). In ordr to compr with othr functionl fturs (xcpt brkg prssur) tht rmind constnt s function of film thicknss nd dmonstrtd tht intrmolculr rction in mtrix hd bn constnt.this is positiv dvition of idl grphs, considring th thicknss, nd shows tht xisting hydrophilic mtril in film tnd to humidity which is not considrd in PHIC nd Hnry lw. Similr bhvior in protin-bsd dibl films, cllulos nd lipid is rportd by diffrnt rsrchrs (Hgnmir 199). Wtr trnsfr modling mong hydrophilic films r grtly complictd du to Isothrm of non-linr wtr bsorption nd wtr contnt dpndd circult(schwrtzbrg 1986). Thus, long with th incrs of protin dry mtril from will b lss. Ths rsults r in grmnt with nd b prmtrs dt nd shows tht by incrs

13 61 Volum 1, No., Summr 015, 49-6 of xisting dry mtril in film, b prmtrs incrss significntly (p<0.05). Elctron microscop Imgs of front nd bck (dorsl) surfc shows tht films contining th lst contnt of dry mtril (fig 5) in compr to thos contining th most hv mor homognous surfc, bcus incrs of dry mtril cuss htrognous surfc tht cn b proposd s probbl rson to phs sprtion. By incrs of protin film dry mtril contnt from %(w/v) to %(w/v), producd film bcoms dnsr nd rt of th film tnsil nd tnsil strngth incrss, howvr du to dcrs of dry mtril solubility, smll crcks form in film cross structur tht lds to th film s WVP. But by incrs of dry mtril contnt from %(w/v) to.5%(w/v) htrognous surfc incrss nd in ddition to obsrvbl crcks on cross sction, thr r som smll hols in surfc structur tht lds to WVP incrs nd dcrs of mchnicl strngth nd film tnsil cpbility of films.5%(w/v) in compr to th films with lss dry mtril. Min rson of th film s surfc crcks prsnc r high incrs of dry mtril, incrs of film thicknss (Tbl 1), lck of polymr structur chins cohsion nd lck of dhsiv structur formtion. Effct of structurl dhsion in protin film on th film functionl fturs hs bn invstigtd in similr rsrchs nd sm rsults hv bn obtind(andrucctti 009) Conclusion Obtind xprimntl rsults from th prsnt rsrch shows tht film s functionl fturs from fish myofibril protin is undr th influnc of glycrol nd dry mtril concntrtion but dos not influnc ll th film fturs. Incrs of glycrol concntrtion cuss th color smpl s rduction. concntrtions in film forming solutions on physicl proprtis of dibl films bsd on muscl protins of Thi Tilpi Journl of food nginring 70: On th othr hnd, mor dry mtril contnt cuss high opcity of smpls in compr to th smpls with lss glycrol. Furthrmor, it is possibl to conclud tht films with highr protin concntrtion, in compr to thos which contins lss protin contnt, shows mor tnsil strngth but this bhvior cn b ffctd by plsticizr concntrtion. Howvr, ll th solution viscolstic fturs won t b ffctd by th protin concntrtion. Rfrncs Andrucctti C, R.A. Crvlho, nd C.R.F. Grosso (009) Effct of hydrophobic plsticizrs on functionl proprtis of gltin-bsd films Food rsrch intrntionl Chinbhrk K, Bnjkul S, Prodprn T (007) Effct of ph on th proprtis of protinbsd film from bigy snppr (< i> Pricnthus tynus</i>) surimi Biorsourc tchnology 98:1-5 CUQ B, AYMARD C, CUQ JL, GUILBERT S (1995) Edibl pckging films bsd on fish myofibrillr protins: formultion nd functionl proprtis Journl of food scinc 60: CUQ B, t l (006) Functionl proprtis of myofibrillr protin bsd biopckging s ffctd by film thicknss Journl of Food Scinc Cuq B, t l. (1997) Slctd functionl proprtis of fish myofibrillr protin-bsd films s ffctd by hydrophilic plsticizrs Journl of Agriculturl nd Food Chmistry D88 A (Stndrd Tst Mthod for Tnsil Proprtis of Thin Plstic Phildlphi: Amrcin Socity for Tsting nd Mtrils,) 001 do A Sobrl PJ, dos Sntos JS, Grcí FT (005) Effct of protin nd plsticizr Ekrmi M, Emm Djomh Z (014) Wtr Vpor Prmbility, Opticl nd Mchnicl Proprtis of Slp Bsd

14 Journl of Food nd Bioprocss Enginring (JFBE) 6 Edibl Film J Food Procss Prsrv 38: Fng Y, t l. (006) Tnsil nd brrir proprtis of dibl films md from why protins Journl of Food Scinc Frinult A, t l. (006) Prprtion of csin films by modifid wt spinning procss Journl of Food Scinc Gnndios A (00) Protin-bsd films nd cotings. CRC, Gontrd N, t l (1994) Edibl composit films of wht glutn nd lipids: wtr vpour prmbility nd othr physicl proprtis Intrntionl journl of food scinc & tchnology Hgnmir RDPES (199) Gs prmbility of fruit coting wxs Journl of th Amricn Socity for Horticulturl Scinc Husr PMADM (1948) Prmtion through nd sorption of wtr vpor by high polymrs. Industril & Enginring Chmistry Krocht JM (00) Protins s rw mtrils for films nd cotings: dfinitions, currnt sttus, nd opportunitis Protin-bsd films nd cotings:1-41 Limpn N, t l. (010) Proprtis of biodgrdbl blnd films bsd on fish myofibrillr protin nd polyvinyl lcohol s influncd by blnd composition nd ph lvl Journl of food nginring Mu C, t l (01) Prprtion nd proprtis of dildhyd crboxymthyl cllulos crosslinkd gltin dibl films Food Hydrocolloids Nolsø H, Undlnd I (009) Th cid nd lklin solubiliztion procss for th isoltion of muscl protins: stt of th rt Food nd Bioprocss Tchnology :1-7 Osw R, Wlsh TP (1993) Effcts of cidic nd lklin trtmnts on tnnic cid nd its binding proprty to protin Journl of griculturl nd food chmistry 41: Pscholick T, Grci F, Sobrl PJA, Hbitnt A (003) Chrctriztion of som functionl proprtis of dibl films bsd on muscl protins of Nil Tilpi Food Hydrocolloids 17: Schwrtzbrg H (1986) Modlling of gs nd vpor trnsport through hydrophilic films Elsvir Applid Scinc Publishrs, Nw York Sircus V, Rocculi P, Romni S, Ros MD (008) Biodgrdbl polymrs for food pckging: rviw Trnds in Food Scinc & Tchnology 19: Sobrl PJA, E. Montrry-Q, nd A.M.Q.B. Hbitnt (007) Glss trnsition study of nil tilpi myofibrillr protin films plsticizd by glycrin nd wtr Journl of Thrml Anlysis nd Clorimtry Thrgorbi R, Bmr SK, Mtk KE, Jczynski J (01) Isolctric solubiliztion/prcipittion s mns to rcovr protin isolt from stripd bss (Moron sxtilis) nd its physicochmicl proprtis in nutrcuticl sfood product Journl of griculturl nd food chmistry Thrnthn R (003) Biodgrdbl films nd composit cotings: pst, prsnt nd futur Trnds Food Sci Tchnol 14:71-78 Zhng YJH (006) Plsticiztion of p strch films with monoscchrids nd polyols Journl of Food Scinc