Physicochemical Characteristics of Gelatin Extracted from Catfish (Clarias gariepinus) and Carp (Cyprinus carpio) Skins

Transcription

1 Middle Est Journl of Agriculture Reserch ISSN Volume : 4 Issue : 2 April-June 215 Pges: Physicochemicl Chrcteristics of Geltin Extrcted from Ctfish (Clris griepinus) nd Crp (Cyprinus crpio) Skins 1 Ali G. M. Mostf, 1 Shltout, O. E., 1 Adllh, A. E., nd 2 Oshe, A. S. ¹ Food Science Dept., Fc. of Agric., S Bsh, Alex. Univ., Alexndri, Egypt. ² Food Tech. Inst., Agric. Res. Center, Giz, Egypt. ABSTRACT Geltins from the skin of two different species of fresh wter fish, nmely Africn ctfish (Clris griepinus) nd Common crp (Cyprinus crpio) hve een successfully extrcted y different concentrtions of sodium hydroxide for vrile times (6,8,1hrs) followed y different concentrtions of sulphuric cid. The mximum yield of geltin ws oserved in crp smples (15.73%) compred to ctfish geltin smples (9.9%). Crp skin geltin exhiited the est clrity (1.68%) nd fom stility (2.4%) compred to ctfish skin geltin (1.9%) wheres, Africn ctfish geltin possed the highest ft inding cpcity. No significnt differences were oserved in the gel strength of ctfish geltin nd ovine geltin (235.73g nd 252.g, respectively.) Similrly, no significnt differences were oserved concerning WHC nd fom formtion mong ll tested geltins. Ornge jelly ws prepred from ovine nd extrcted fish geltins. Results indicted no significnt differences concerning the tste, texture nd color etween ovine nd common crp geltin jelly except for overll cceptnce where ovine geltin recorded the highest score(4.83) followed y commn crp geltin(4.16). None of the orgnoleptic properties of the tested jellies reched the limit of rejection. The fresh wter fishes investigted in the present study my e potentil lterntive sources of geltin. Key words: Fish geltin, Fresh wter fish, Extrction nd chrcteriztion, Alterntive resource of geltin. Introduction Geltin is n importnt functionl iopolymer widely used in foods to improve elsticity, consistency, nd stility. It cn e otined not only from the skin nd ones of lnd nimls, ut lso from fish nd insects. In recent yers geltins from fish nd edile insects provide n lterntive source tht is cceptle for hll (Muslim) nd kosher (Jewish) products. Geltin from mrine sources (wrm-nd cold-wter fish skin, ones nd fins) is possile lterntive to ovine geltin (Wssw et l., 27). Geltin is otined through hydrolysis of collgen, which is the principl protein found in skin nd ones. It is n ingredient widely used in food industry, phrmceuticl, medicl, cosmetic nd photogrphic industries due to its unique functionl nd technologicl properties (Krim nd Bht, 29). Recent reports indicte tht the nnul world output of geltin is incresing, especilly in Asi, nd it is mostly otined from pig nd cow skins nd ones (Gomez-Guillen nd Montero, 21; GME, 28). However, the use of geltin from those resources is restricted due to the outreks of ovine spongiform encephlopthy (BSE) or md cow disese nd religious resons. Therefore, there is n incresing interest in the production of fish geltin s n lterntive for mmmlin counterprt (Gudmundsson et l., 22). In recent yers, extrction nd chrcteristic of geltin properties hs een reported from vrious sources such s the skins of lck tilpi (Oreochromis mossmicus) nd red tilpi (Oreochromis nilotic), nile pech (Ltes niloticus) skin nd one geltin (Muyong et l., 24), sin croker nd shortfin scd (Cheow et l., 27), kerpu (Epinephelus sexfscitus), jenhk (Lutjinus rgentimcultus), kemung (Rstrelliger kngurt), nd kerisi (Pristipomodes typus) (Irwndi et l., 29), crp (Cyprinus crpio ) (Dun et l., 211), ctfish (Liu et l., 28) nd red tilpi (Oreochromis nilotic), wlking ctfish (Clris trchus) nd striped ctfish (Pngsius sutchi fowler) (Jmilh et l., 211). The mjor physicl properties of geltin re gel strength nd melting point, which re governed minly y the mino cid composition (proline + hydroxyl proline content), moleculr weight distriution nd lso the rtio of α/β chins in the geltin (Krim nd Bht, 29). The mino cid content in geltin is dependent on the origin of the rw mterils. Mny studies hve indicted tht collgen extrcted from wrm wter fish species contins more mino cids thn tht of cold wter fish (Gudmundsson, 22). However, the lter hs weker gelling properties due to the low content of proline nd hydroxy proline compred to the ovine nd porcine derived geltins. There is very limited informtion of collgen derived from fresh wter fish s n lterntive geltin source. The im of the present reserch is to identify the est extrction condition nd determine some Corresponding Author: Ali Gml Mhmod Mostf, Food Science Dep., Fc. of Agric., S Bsh, Alex. Univ., Alexndri, Egypt.) E-mil: ligml22@hotmil.com 359

2 Middle Est J. Agric. Res., 4(2): , 215 physicochemicl chrcteristics of geltin extrcted from the skin of some fresh wter fish (ctfish nd common crp) s rw mterils compred with commercil ovine geltin found in locl mrket in Alexndri- Egypt. Mterils nd Methods Mterils: The rw mterils used in the present study re the skins of two cultured freshwter fishes Common crp (Cyprinus crpio) nd Africn ctfish (Clris griepinus). Smples were rought from Berciq freshwter frm locted in Kfr El-Dwr, El-Beher, Egypt in Octoer 213. Pretretment of fish skins prior to min extrction The geltin extrction procedure followed ws essentilly s descried y Grossmn nd Bergmn (1992) with slight modifictions. The clened nd drined fish skins were given pretretment with n lkline solution followed y n cid solution. Clened skins were tken in conicl flsk nd treted with different concentrtions of sodium hydroxide (1:6 w/v) for vrile times. The smples were then rinsed with tp wter nd drined using cheesecloth. The ove tretment ws repeted for 2 times. The smples were treted with different concentrtions of sulphuric cid (1:6 w/v) for vrile times. The smples were then rinsed with tp wter nd drined using cheesecloth. The cid tretment ws lso repeted two times. The treted smples were squeezed mnully using cheesecloth to remove excess wter prior to the extrction. The conditions followed for the pretretment re given in Tle(1). Tle1: Process vriles dopted for the pretretment of fish skins. Process vriles Conc.( mol/l) NOH concentrtion H2SO4 concentrtion Pretretment time (minutes) Geltin extrction The pretreted fish skins were tken in flsks for geltin extrction with vrying volumes of deionized wter, extrction time nd temperture (Tle 2). The flsks were covered with prfilm nd the extrction ws crried out in wter th. Finlly, the geltin solutions were filtered through 4 lyers of cheesecloth, nd dried prior to further work. Tle 2: Process vriles dopted for the extrction of geltin. Process vriles Rnge Skin/wter rtio 1:4 1:5 1:6 Extrction time 6h 8h 1h Extrction temperture 4 C 5 C 6 C Physicochemicl nlysis Yield: Yield of geltin extrcts produced from ech fish ws determined ccording to the following eqution: % yield = weight of geltin/weight of skin x 1% (AOAC, 2). Proximte nlysis: proximte nlysis (moisture, sh, protein nd ft contens) were crried out ccording to AOAC (2). Geltin color: Color of geltin gels were mesured sed on the method descried y Jmilh et l. (211) using HunterL MiniScn XE Plus Spectrocolorimeter (Hunter Assocites Lortory Inc., Reston, VA, USA). Smples were red three times nd reported s L*, * nd * prmeters indicting lightness, redness/greenness nd yellowness/ lueness. Determintion of mino cid composition Amino cids were determined ccording to the methods descried y Moore (1958). Smple of 2-25mg ws plced in glss hydrolysis tue contining 1 ml of 6N HCL with.1% mercptoethnol. The tue ws seled nd heted in n oven t 11ᵒC for 24 hrs. The hydrolyzed smple ws then cooled to room temperture nd filtered through Whtmn No 1 filter pper. The tue nd precipitte on the pper ws wshed with distilled wter nd the filtrtes were then completed to 25 ml in volumetric flsk. Five ml of the filtrte were trnsferred to 25 ml eker nd plced under vcuum in desicctors over potssium hydroxide. The resulted dried residue ws dissolved in one ml of sodium citrte uffer of PH 2.2 nd stored t 4ᵒC until nlyzed y Beckmn Amino Acid Anlyzer Model 119 CL. 36

3 Middle Est J. Agric. Res., 4(2): , 215 Determintion of gel strength Geltin t rte of 7.5 ±.1 g ws weighed into the Bloom ottle nd 15 ±.2 ml deionized wter ws dded nd stirred (BS 757:1975). For determining the gel strength, the plunger of the Texture Anlyzer ws set to move distnce 4 mm into the gel with speed of.5 mm/sec. The vlue given y the Texture Anlyzer ws the gel strength (BS 757:1975). Determintion of Viscosity Geltin solutions t concentrtion of 6.67%(w/v) were prepred y dissolving the dry powder in distilled wter nd heting t 6 C. Viscosity (cp) of 1 ml of the solution ws determined using Brookfield Digitl Viscometer( Model DV E Brookfield Engineering, USA) equipped with No.1 spindle t 3±.5 C (Cho et l., 26). Determintion of geltin ph The ph vlues of rw fish skins nd geltin solutions were mesured using 1% (w/v ) solution of geltin prepred in distilled wter t 6 C, cooled to room temperture nd the ph ws mesured using (Adw AD13 PH/ MV & Temperture Meter. Mde in Romni, Europe) s descried y Vreltzis et l. (1997). Determintion of setting point nd setting time The method used for the determintion of setting point (SP) nd setting time (ST) of geltin ws tht descried y Muyong et l., (24). Determintion of foming properties Fom formtion ility (FA) nd fom stility (FS) of geltin were determined y the procedure of Cho et l., (24). The fom stility ws clculted s the rtio of the initil volume of fom to the finl volume of fom fter 3 min. Determintion of ft inding cpcity nd wter holding cpcity Ft inding cpcity (FBC) nd wter holding cpcity (WHC) were mesured s follows : One g of geltin powder ws plced in centrifuge tue nd weighed. Then, ten ml sunflower oil ws dded, nd held t room temperture for 1 h. During this period, the geltin solutions were mixed with Vortex mixer (CM-11 Plus, REMI Instruments, Mhrshtr, Indi) for 5 s every 15 min. The geltin solutions were then centrifuged t 45 g for 2 min with cylinder ottom centrifuge of 2 ml cpcity (Model CPR 24, Indi). The upper phse ws removed y tilting the centrifuge tue to 45 ngle nd drining on to filter pper for 3 min. The FBC ws clculted s the weight of the contents of the tue fter drining divided y the weight of the dried geltin, nd expressed s the weight % of dried geltin (Cho et. l., 24). For mesuring WHC, one g of geltin powder ws plced in centrifuge tue nd weighed (tue with geltin). Distilled wter (5 ml) ws dded, nd held t room temperture for 1 h. During this period, the geltin solutions were mixed with Vortex mixer (CM-11 Plus, REMI Instruments, Mhrshtr, Indi) for 5 s every 15 min. The geltin solutions were then centrifuged t 45 g for 2 min (Hereus Multifuge 3SR Plus, Thermo Scientific, MK, Buckinghmshire, Englnd). The upper phse ws removed nd the centrifuge tue ws drined for 3 min on filter pper fter tilting to 45 ngle. WHC ws clculted s the weight of the contents of the tue fter drining divided y the weight of the dried geltin, nd expressed s the weight % of dried geltin (Cho et. l., 24). Clrity Geltin t rte of 7.5 g (±.1) ws weighed into 15 ml ottle nd 15 ml (±.2) wter ws dded. The sornce t 62 nm ws mesured t room temperture ginst deionized wter (ISO 727:1999). Determintion of geltin odor Oder evlution ws conducted using seven memer expert pnel ccording to the method of Muyong et l., (24). The smples were prepred in test tues with screw cps, y dissolving.5 g of geltin in 7 ml of distilled wter, thus otining solution contining pproximtely 6.67% geltin. The tues were then held in wter th t 5 C for dissolving, with the screw cps closed. Pnelists were instructed to remove the screw cps, sniff the contents nd identify the odour they perceived s well s to indicte the odour intensity, using five point scle. i.e., = no odour, 1 =very mild nd only perceivle on creful ssessment, 2 = mild ut esily perceivle, 3 = strong ut not offensive, 4 = strong nd offensive, 5 = very strong nd very offensive. 361

4 Middle Est J. Agric. Res., 4(2): , 215 Sensory Evlution:- Geltin Jelly Preprtion: Geltin jelly were prepred s descried y Zhou & Regenstein, (27) y dissolving geltins in flvored ornge juice (prepred from ornge flvor instnt drink mix, Bity Foods Ltd., Egypt.) heted to 45 5 C. Sensory evlution of the jelly from ovine nd prepred fish skin geltin were sujected to pnelist. Smples were served long with wter nd unslted crckers to 5 trined memers from the Dept. of Food science. Pnelists were instructed to rinse with wter nd consume crckers fter tsting the next smples. Empty cups were provided for expectortion of the smples (Krmer nd Twigg, 197). The pnelists received 5 smples t ech testing period. Sensory scores for colour, tste, odour, texture nd overll cceptnce were determined using five-point hedonic scle s follow: 5 = nondetectle off flvour nd 1 = extreme off flvor, 5 = typicl fresh colour nd 1 = fint colourtion nd 5 = firm nd juicy nd 1 = soft nd firous for texture. (IFT/ SED, 1981). The geltin jelly prepred hd geltin concentrtion of (3%w/w) ccording to Zhou & Regenstein (27). The finl composition of the jelly is shown in tle (3). Tle 3: Composition nd ph of Geltin jelly* BG TG CG Geltin (g) Wter (g)* Sugr (g)* Others (g)* <1. <1. <1. Finl ph *BG=Bovine Skin Geltin W(225B); TG= Ctfish Skin Geltin; CG = Common crp Skin Geltin; The mount of wter nd sugr re clculted sed on the ingredient lel of the flvored ornge juice. Sttisticl nlysis: The otined dt were sujected to nlysis of vrince (ANOVA) n Duncn's multiple rnge tests to differentite etween tretments mens (P<.5) using SAS progrm (SAS,1995). Results nd Discussions Yield of geltin The yield of geltin from the different species of fresh wter fish re shown on Tle (4).The highest yield ws otined from common crp( B2, B3 nd B1) eing %, 15.3% nd %, respectively. The yield of geltin from Africn ctfish were (A2, A3 nd A1) were 9.9%, 8.59% nd 7.576%, respectively. The forementioned result were higher thn tht reported y Jmilh nd Hrvinder (22), where the yield of extrcted geltin of red tilpi nd lck tilpi were 7.81% nd 5.39%, respectively; higher thn tht of sin crocker (14.3%) s reported y Cheow et l., (27), s well s tht of squid (7.5%) s reported y Urirte et l., (211). Similrly, it ws lso higher thn those reported y Gomez-guillen et l., (22) for Sole (7.3%), megrim (7.4%), cod (7.2%) nd megrim (6.5%); Muyong et l., (24) for young nile perch (12.5%) nd slmon 11.3%; nd lso for cod (1.1%) s reported y Arnesen nd Gilderg (27). Those results my e explined s the different kind of skin, cid concentrtion, ph condition, the rte of collgen rek down were mong the possile resons for the high geltin yield from the two species of fresh wter fish. Gomez-Guillen et l., (21) noted tht the different mrine species hs different structurl nd physicl properties of geltin. While Jmilh nd Hrvinder (22), Songchotikunpn et l. (28), nd Trestni et l., (21) suggested tht the wide diversity mong the fish species present intrinsic differences in the collgen molecules present in their skin. Moreover, the higher susceptiility of the collgenous mteril from fish skin to degrdtion is due to the lower content in intr- nd interchin non-reducile crosslinks. While Krim nd Bht (29) noted tht the yield nd qulity of geltin re influenced y the species nd ge of the fish, extrction process nd pretretment temperture. Tle 4: Yield* of Clris griepinus nd Cyprinus crpio geltins ** SAMPLE A1 A2 A3 B1 B2 B3 YEILD 7.576±.21e 9.9±.29 c 8.59±.2 d ± ± ±.17 * Mens of triplictes ± S.D. **A1 Clris griepinus geltin extrcted t(4 C, 6 hrs, skin/wter rtio 1:4), A2 Clris griepinus geltin extrcted t(5 C, 8 hrs, skin/wter rtio 1:5), A3 Clris griepinus geltin extrcted t(6 C, 1 hrs, skin/wter rtio 1:6), B1 Cyprinus crpio geltin extrcted t(4 C, 6 hrs, skin/wter rtio 1:4), B2 Cyprinus crpio geltin extrcted t(5 C, 8 hrs, skin/wter rtio 1:5), B3 Cyprinus crpio geltin extrcted t(6 C, 1 hrs, skin/wter rtio 1:6). Color mesurement of geltin y Hunter l The geltin otined from the different species of fresh wter fish nd its ppernce re shown in Tle (5). The lightness (L*) vlue of geltin extrcted from Africn ctfish skin (91.77) nd common crp (9.44) were higher compred to the commercil geltin (61.73). However, * (redness) nd * (yellowness) vlue of 362

5 Middle Est J. Agric. Res., 4(2): , 215 commercil geltin ws higher thn those of lter fresh wter fish geltin. Ockermn nd Hnsen (1999) noted tht the ppernce of geltin from striped snkehed visully re close to tht of commercil one wheres pngs ctfish nd Asin redtil ctfish geltin re similr to pig geltin. The color of the geltin depends on the rw mteril. However, it does not influence other functionl properties. The lighter color of geltin my hve more commercil stisfction. Tle 5: Color of extrcted Geltin s mesured y Hunter L from the skin of Ctfish nd Common crp* Fish skin geltin L* * * Ctfish 91.77± ± ±.5 Common crp 9.44± ± ±.4 * Results re mens ± stndrd devition (n = 3). L*= The lightness *= Redness *= Yellowness Proximte composition of geltin Tle (6) nd (7) shows the proximte composition of geltin extrcted from two different fresh wter fish. Protein content of Africn ctfish A1,A2,A3 nd common crp B1, B2 nd B3 were 88.7%; 87.31% nd 87.69% nd 87.25%; 87.2% nd 87.48%, respectively. All were significntly different thn tht of commercil geltin (78.9%). Ash content of geltin from the two different fresh wter fishes studied were lower to tht suggested y Jones (1997) which reched mximum of 2.6%; for instnce rown stripe red snpper is 1.9% (Jongjreonrk et l., 26), sin croker nd shortfin scd 1.49% nd 1.15%, respectively (Cheow et l., 27) nd nile perch.4% (Songchoticupn et l., 28). Benjkul et l. (29) noted tht high qulity of geltin should contin no more thn.5% sh. Jongjreonrk et l., (26) suggest tht the high protein content nd the less moisture, sh nd ft contents re determined y rw mteril or my e contriuted y the residul of chemicls fter processing, or lso the possiility of mixing with other ingredients. Tle 6: Proximte chemicl composition* of Clris griepinus geltin** on wet ses (%) Tretments Moisture Lipid Protein Ash A1 8.55±.4.59± ± ±.2 A2 8.3±.12 c.52±.4 c 87.31± ±.2 A3 8.22±.5 c.5±.2 c 87.69± ±.2 * Mens of triplictes ± S.D. **A1 Clris griepinus geltin extrcted t(4 C, 6 hrs, skin/wter rtio 1:4), A2 Clris griepinus geltin extrcted t(5 C, 8 hrs, skin/wter rtio 1:5), A3 Clris griepinus geltin extrcted t(6 C, 1 hrs, skin/wter rtio 1:6). Tle 7: Proximte chemicl composition* of Cyprinus crpio geltin** on wet sis (%) Tretments Moisture Lipid Protein Ash B1 8.41±.14.65± ± ±.2 B2 8.18±.9 c.63± ± ±.3 B3 8.16±.16 c.59± ±.6 1.1±.3 * Mens of triplictes ± S.D. **B1 Cyprinus crpio geltin extrcted t(4 C, 6 hrs, skin/wter rtio 1:4), B2 Cyprinus crpio geltin extrcted t(5 C, 8 hrs, skin/wter rtio 1:5), B3 Cyprinus crpio geltin extrcted t(6 C, 1 hrs, skin/wter rtio 1:6). Amino cid composition Amino cid composition of different species of fresh wter fish is presented in Tle (8). Since the hrdness of geltin gel ws in direct correltion with prolin (pro) nd hydroxyproline (hyp) (Holzer, 1996) content. As cn e seen, Glycine nd proline found in Africn ctfish geltin were 21.69g/1g nd 11.65g/1g, respectively nd it ws higher compred to tht of common crp which were 19.2g/1g nd 2.94g/1g, respectively. Gόmez-Guillèn et l., (22) report tht the mino cids composition of geltin extrcted from the skin of sole, megrim, cod, hke nd squid hd more thn 3% Gly nd ~17% imino cids.in the present study the glycine content of geltin in oth species rnged etween g/1g wheres proline & hydroxyproline rnged etween g/1g. However, Jmilh nd Hrvinder (22) report tht the proline contents of the geltins extrcted from red nd lck tilpi is very low nd lmost undetectle. Glutmic cid is the third order from mino cid fter glycine nd proline. In the present study, the glutmic cid of Africn ctfish 13.15g/1g nd common crp ws 12.96g/1g. On the other hnd, lnine in common crp geltin (3.16 g/1g) ws higher compred to tht of Africn ctfish (1.81 g/1g). On the contrry, rginine of Africn ctfish geltin (7.19 g/1g) ws higher compred to tht of common crp geltin (5.24 g/1g). The mino cid composition ply min role in the physicl properties of geltin. The mino cid nlysis of geltin is vrile, prticulrly for the minor constituents, depending on rw mteril nd process used, ut proximte vlues y weight s descried y (Stevens, 1992) re:- glycine 21 %, proline 12 %, hydroxyproline 12 %, glutmic cid 1 %, lnine 9 %, rginine 8%, sprtic cid 6 %, lysine 4 %, serine 4 %, leucine 3 %, vline 2 %, phenyllnine 2 %, threonine 2 %, isoleucine 1 %,hydroxylysine 1 %, methionine nd histidine <1% with tyrosine <.5 %. 363

6 Middle Est J. Agric. Res., 4(2): , 215 ph The ph of the extrcted fish geltins is given in Tle (9). The ph vries etween 3.99 nd 4.7. Africn ctfish geltin shows significntly higher vlues (p<.5) thn tht of common crp geltin. The vlues of ph for geltin smples in the present study re outside the rnge prescried for ctfish A geltin (ph ) nd common crp B geltin (ph ). This my e due to the pretretment method employed during the extrction process which involves oth lkli nd cid tretments. Functionl properties of geltins viz., gel strength nd melting point re dependent on ph. Choi nd Regenstein (2) oserved tht the gel strength of the fish nd pork geltins decresed mrkedly elow ph 4 nd slightly ove ph 8. For the melting point lso similr dependencies were oserved in reltion to ph. The ph reported for geltin extrcted from the skin of red nd lck tilpi ws 3.5 nd 3.91 respectively (Jmilh & Hrvinder, 22). Tle 8: Amino cid composition of geltin from Ctfish nd Crp skin* Amino cid Ctfish geltin Crp geltin FAO provisionl pttern Leucine 3.28±.2 2.7±.2 9. Isoleocine.17±.9.73±.5 Threonine 4.9± ± Vline 3.15± ± Methionine 2.43± ± Essentil mino cids phenyllnine 1.92±.1.67± Lysine 3.31± ± Histidine.69±.1.39±.11 Arginine 7.19± ±.9 Asprtic cid 2.3±.3 2.6±.1 Serine 6.66± ±.3 Glutmic cid 13.15± ±.5 Glycine 21.69± ±.2 Alnine 1.81± ±.2 Proline 11.65± ±.3 Ammoni.18±. 1.4±.7 Cystine 1.12±.4.86±.6 Tyrosine 4.2±.2 3.7±.4 Hydroxyl proline 8.1± ± Totl 96.11± ±6.28 Proline+ Hydroxyl proline 19.66± ±.45 *Results otined re mens of duplicte redings ± SD. Non essentil mino cids Tle 9: PH* of Clris griepinus nd Cyprinus crpio geltin** Smple A1 A2 A3 B1 B2 B3 PH 4.7±.1 4.4±.2 4.3±.2 4.3±.3 4.3± ±.2 * Mens of triplictes ± S.D. **A1 Clris griepinus geltin extrcted t(4 C, 6 hrs, skin/wter rtio 1:4), A2 Clris griepinus geltin extrcted t(5 C, 8 hrs, skin/wter rtio 1:5), A3 Clris griepinus geltin extrcted t(6 C, 1 hrs, skin/wter rtio 1:6), B1 Cyprinus crpio geltin extrcted t(4 C, 6 hrs, skin/wter rtio 1:4), B2 Cyprinus crpio geltin extrcted t(5 C, 8 hrs, skin/wter rtio 1:5), B3 Cyprinus crpio geltin extrcted t(6 C, 1 hrs, skin/wter rtio 1:6). Physicochemicl Properties of Geltin Gel strength The gel strength of Africn ctfish geltin s shown in Fig. (1) exhiited significnt higher gel strength vlue (235.73g) thn common crp (185.32g). No significnt differences were oserved etween the gel strength of oth AG nd CG. The gel strength of Africn ctfish nd common crp in the present study were considerly high when compred to those reported in other studies, such s geltins from red tilpi (128.1 g), Blck tilpi skin 18.7g (Jmilh nd Hrvinder, 22), Slmon 18g (Zhou et l., 26). Gudmonsson nd Hfsteinsson (1997) noted tht the gel strength proly depend on the isoelectric point nd control of ph. The gel strength of commercil geltin hs rnge vlue of 2-3 g nd melting point is >3ᵒC. The gel strength of cold mrine species is 1 g or less nd melting temperture is <17ᵒC, wheres wrm wter species is higher thn 2 g nd melting temperture 24-29ᵒC. Viscosity Viscosity is the second most importnt commercil physicl property of geltin. Fig (2) shows the different viscosities of the two fish species of fresh wter fish compred to commercil ovine geltin. The viscosity otined from Africn ctfish nd common crp were 6.2 cp nd 5.96 cp, respectively with no significnt differences etween them. These results were significntly less thn tht of commercil geltin 364

7 Middle Est J. Agric. Res., 4(2): , 215 (6.77cP). The viscosity increses with incresing gelling temperture, melting temperture, melting point nd gel strength (Schrieer nd Gries, 27). Grossmn nd Bergmn (1992) report tht the viscosity of tilpi geltin, wlking ctfish nd striped ctfish re 7.7 cp, 6.28 cp nd 8.21cp, respectively. However, Yng et l., (27) report less viscosity (<3. cp) for chnnel ctfish geltin. Gel strength Gel strength 1 5 Tretments Fig.1: Gel strength of Africn ctfish geltin, common crp geltin nd mmmlin Gelti (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) Viscosity CP/1ML 7 Viscosity CP/1ML Tretments Fig.2: Viscosity of Africn ctfish geltin, common crp geltin nd mmmlin Geltin (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine). Clrity Crp skin geltins in the present study BG exhiited etter clrity thn AG. As mtter of fct, no significnt differences were oserved etween geltin clrity of common crp nd ovine geltin (Fig.3.). High temperture extrction cn result in higher moleculr weight ggregtes which will increse the turidity of the gel nd ffect the clrity (Montero et. l., 22). Clrity is importnt in commercil pplictions nd this property is frequently ssessed for determining the qulity of gels. Setting Temperture nd Setting Time. Results of setting temperture (Fig 4) indicted tht ovine geltin exhiited significntly higher setting tempertures (32.94 C) thn Africn ctfish geltin(19.ᵒc) nd common crp skin geltin(17.9ᵒc).setting temperture of geltin hs lso een found to correlte with the imino cid content which is ~24% for mmmls nd 16-18% for most fish species (Choi & Regenstein, 2; Gilsenn & Ross-Murphy, 2; Gudmundsson, 365

8 Middle Est J. Agric. Res., 4(2): , ; Leuenerger, 1991). Collgens derived from fish species living in cold environments hve lower contents of hydroxyproline nd they exhiit lower therml stility thn those from fish living in wrm environments. This is ecuse hydroxyproline is involved in inter-chin hydrogen onding, which stilizes the triple helicl structure of collgen (Dry & Creighton, 1993). The gel setting time ws significntly fster in ovine geltin (63.96 seconds) compred to common crp nd ctfish skin geltins with no significnt differences etween them (Fig 5). Common crp skin gel nd Africn ctfish hd setting time of (13.19) nd (16.9) seconds, respectively. Clrity % Clrity % 1.5 Tretments Fig.3: Clrity of Africn ctfish geltin, common crp geltin nd mmmlin geltin Clrity (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) Setting temperture C Setting temperture C Tretments Fig.4: Setting temperture of Africn ctfish geltin, common crp geltin nd mmmlin Geltin (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) Foming Formtion nd Fom Stility The foming formtion (ility) nd fom stility of Africn ctfish, common crp nd ovine geltins re given in Fig. (6). Results show tht there is no significnt differences etween oth fish geltins in respect to fom formtion. The hydrophoic res on the peptide chin re responsile for giving geltin its emulsifying nd foming properties (Cole, 2 nd Glzk, et l., 1999). Fom formtion of oth geltins of fish species 2.68% & 2.45%, under study showed no significnt differences compred to ovine geltin (2.75%). Fom stility (Fig7) ws significntly higher for common crp (2.4%) thn for mmmlin nd Africn ctfish geltins eing 1.7 nd 1.9, respectively. The reduced fom formtion nd stility my e due to ggregtion of proteins which interfere with interctions etween the protein nd wter needed for fom formtion (Kinsell, 1977). 366

9 Middle Est J. Agric. Res., 4(2): , 215 Setting time SEC Setting time (SEC) Tretments Fig.5: Setting temperture of Africn ctfish geltin, common crp geltin nd mmmlin Geltin (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) Fom formtion Fom formtion Tretments Fig.6:Fom formtion of Africn ctfish geltin, common crp geltin nd mmmlin geltin(*ag=africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) Fom stility Fom stility 1.5 Tretments Fig7:Fom stility of Africn ctfish geltin, common crp geltin nd mmmlin geltin(*ag=africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) 367

10 Middle Est J. Agric. Res., 4(2): , 215 Ft inding cpcity nd Wter holding cpcity Ft inding cpcity of Common crp, Africn ctfish nd mmmlin geltins re given in Figure (8). It cn e oserved tht ctfish geltin exhiited the highest ft inding cpcity nd ws significntly different from oth crp nd ovine geltins. Ft inding cpcity depends on the degree of exposure of the hydrophoic residues inside the geltin. The high vlue of ft inding cpcity of Africn ctfish skin geltin my e due to the highest percentge of hydrophoic residue tyrosine (Cho, et. l., (24). Wter holding cpcity of Common crp, Africn ctfish nd mmmlin geltins re given in Figure (9). As mtter of fct no significnt differences were oserved in the wter holding cpcity, mong Africn ctfish, common crp nd ovine geltins.wter-holding cpcity is ffected y the mount of hydrophilic mino cids like hydroxyproline. In the present study the highest wter holding cpcity ( %) ws oserved for ovine geltins, this my e due to significntly higher percentge of hydroxyproline of ovine geltin s compred to oth fish species ( nd 177), respectively. Wter-holding nd ft-inding cpcities re functionl properties tht re closely relted to texture y the interction etween wter, oil nd other components. Ft inding cpcity c 2 Ft inding cpcity 1 AG CG BG Tretments Fig. 8: FBC of Africn ctfish geltin, common crp geltin nd mmmlin Geltin (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine) 25 WHC 2 15 WHC 1 5 AG CG BG Tretments Fig.9: WHC of Africn ctfish geltin, common crp geltin nd mmmlin Geltin (*AG=Africn ctfish geltin, BG=Common crp geltin nd CG= Commercil geltin(bovine). 368

11 Middle Est J. Agric. Res., 4(2): , 215 Odor of different fish geltins:- Odor scores s judged y pnelists of oth fish geltins re given in Fig(1). The odor scores were significntly higher for Africn ctfish nd common crp skin geltins (3.8 nd 2.), respectively, indicting tht they hd distinguishle fishy odor nd hence cn e considered s inferior to ovine geltin in orgnoleptic qulities. On the other hnd, Choi & Regenstein (2) oserved tht fish geltins hd less off odor nd etter rom thn pork geltins on sensory evlution. odor odor Tretments c Fig.1: Odor of Africn ctfish geltin, common crp geltin nd mmmlin geltin (*AG=Africn ctfish geltin, BG=Common crp geltin n CG= Commercil geltin(bovine) Sensory Evlution of fish skin geltin jelly compred to ovine geltin jelly Tle (1) nd Fig (11) show the ornge jelly prepred from oth fish nd ovine geltins. Results indicted tht pnelists could not differentite etween color of different ornge jellies prepred with fish skin geltin nd ovine geltin s there were no significnt differences etween them.as mtter of fct, odor of the jelly prepred y ovine geltin ws significntly different (4.5) from tht prepred from the fish geltins, ut still the lter were modertely ccepted ( Tple1). As for the tste, fortuntely no significnt different were oserved etween the three types of jellies. Tste is the most importnt sensory ttriute. Regrding this spect, there were no significnt difference etween ll smples, ut still the ovine jelly exhiit numericl higher scores (3.83) compred to fish geltin jellies. Concerning the texture, there were no significnt differences etween ll smples. Both fish geltin jellies exhiited higher numericl scores compred to ovine jelly eing (4.25 nd 4.16), respectively. As for the overll cceptnce, the ovine geltin jelly (GAC) nd common crp geltin jelly (GA2), were the most cceptle nd the most highly scored, s compred to ctfish geltin jelly (GA1). However, Choi & Regenstein (2) noted tht flvored fish geltin dessert gel product hd less undesirle off-flvors nd off-odors, with more desirle relese of flvor nd rom thn the sme product produced with pork geltin possessing equl Bloom vlues, ut higher melting point. As mtter of fct, none of the sensory prmeters reched the level of rejection, this my lso ssure the fct tht fish geltins cn e used successfully in prepring jelly products. Also, the texture of the prepred jellies with different geltins in the present study showed no significnt differences thus emphsizing the fct tht fish geltin in the present study could e used successfully in mnufcturing jelly-type products. Tle 1: Sensory ssessment* of ornge jelly processed from different fish skin geltins nd ovine geltin Tretments Color odor tste texture cceptnce GAC 4.83±.4 4.5± ± ± ±.25 GA2 2.83± ±.51 3.± ± ±.4 GA1 3.66± ± ± ± ±.54 c * Mens with different superscripts in rw or column re significntly different t (p<.1) GA1 = Africn ct fish skin geltin. GA2 = Common crp skin geltin. GAC = ovine geltin. 369

12 Middle Est J. Agric. Res., 4(2): , 215 Fig.11 : Geltin jelly smple ( GA1 = Africn ct fish skin geltin. GA2 = Common crp skin geltin. GAC = ovine geltin). References A.O.A.C., 2. Officil Methods of Anlysis of the Assocition of Officil Agriculturl Chemist 2th Ed. Wshigton DC. USA. Arnesen, J.A. nd A. Gilderg, 27. Extrction nd chrcteriztion of geltine from Atlntic slmon (Slmo slr) skin. Bioresource Technology 98 (1): Benjkul, S., K. Oungho, W. Visessngun, Y. Thinsilkul nd S. Roytrkul, 29.Chrcteristic of geltin from the skins of igeye snpper, Pricnthus tyenus nd Prichnthus mcrcntus. Food Chemistry 116: BSI (British Stndrd Institution), Methods for Smpling nd Testing Geltin (Physicl nd Chemicl Methods) London, BSI, BS 757. Cheow, C.S., M.S. Norizh, Z.Y. Kyw nd N.K. Howell, 27. Preprtion nd chrcteriztion of geltins from the skins of skins of sin croker (Johnius dussumieri) nd shortfin scd (Decpterus mcrosom). Food Chemistry. 11: Choi, S.S. nd J.M. Regenstein, 2. Physichochemicl nd sensory chrcteristics of fish geltin. Journl Food Science 65 : Cho, SH., M.L. Jhncke, K.B. Chin, nd J. B. Eun, 26. The effect of processing conditions on the properties of geltin from skte (Rj kenojei) skins. Food Hydrocoll.2, Cho, S.M., K.S. Kwk, D.C. Prk, Y.S. Gu, C.L. Ji, D.H. Jng, Y.B. Lee nd S.B. Kim, 24.Processing optimiztion nd functionl properties of geltin from shrk (Lsurus oxyrinchus) crtilge Food Hydrocoll.18, Cole, C. G. B., 2. Geltin. in F. J. Frncis (Ed.), Encyclopedi of food science nd technology (2nd Ed.). New York: John Wiley & Sons, 4 Vols-JJD Dry, J. N., nd T. E. C. Creighton, Protein structure. Oxford University Press, Oxford, 455p. Dun, R., J. Zhng, F. Xing, K. Konno nd B. Xu, 211. Study on the properties of geltins from skin of crp (Cyprinus crpio) cught in winter nd summer seson. Food Hydrocolloids 25: Glzk, V. B., E. Dickinson nd D. A. Ledwrd, Emulsifying ehvior of gloulin Vici f in mixtures with sulphted polyscchrides: Comprison of therml nd high-pressure tretments. Food Hydrocoll,13, pp Gilsenn, P.M. nd S.B. Ross-Murphy, 2. Rheologicl chrcteriztion of geltins from mmmlin nd mrine sources. Food Hydrocolloids 14: GME: Internet: Geltin Mnufctures of Europe. 28. Officil wesite of GME. Downloded from on 8/3/211. Gomez-Guillen, M.C. nd P. Montero, 21. Extrction of geltin from megrim (Lepidorhomus oscii) with severl orgnic cids. Journl of Food Science 66 (2): Gomez-Guillen, M.C., A.L. Sri, M. T. Sols, nd P. Montero, 21. Effect of microil trnsglutminse on the functionl properties of megrim (Lepidorhomus oscii) skin geltin. Journl of the Science Food nd Agriculture 81:

13 Middle Est J. Agric. Res., 4(2): , 215 Gomez-guillen, M.C., J. Turny, M.D. Fernndez-Diz, N. Ulmo, M. Lizre, nd P. Montero, 22. Structurl nd physicl properties of geltin extrcted from different mrine species. A comprtive study. Food Hydrocolloids, 16, Grossmn, S. nd M. Bergmn, Process for the production of geltin from fish skin. United Sttes Ptent. No. 5,93,474. Gudmundsson, M., nd H. Hfsteinsson, Geltin from cod skins s ffected y chemicl tretments. Journl of Food Science. 62: Gudmundsson, M. 22. Rheologicl properties of fish geltin. Journl of Food Science 67: Holzer, D., Geltin production. US. Ptent 5,484, 88. Internet: Geltin Mnufctures of Europe. 28. Officil wesite of GME. Downloded from on 8/3/211. IFT/SED,1981. Sensory evlution guideline for testing food nd everge products. Food Technol. 35: ISO: 727 (Interntionl Orgniztion for Stndrdistion,1999) Wte Qulity-Determintion of Turidity. Irwndi, J., S. Fridynti, E.S.M. Mohmed, M.S. Hmzh, H.H. Torl, nd Y.B. Che Mn, 29. Extrction nd chrcteriztion of geltin from different mrine fish species in Mlysi. Interntionl Food Reserch Journl 16: Jmilh, B. nd K.G. Hrvinder, 22. Properties of geltins from skins of fish-lck tilpi (Oreochromis mossmicus) nd red tilpi (Oreochromis nilotic). Food Chemistry 77: Jmilh, B., K.W. Tn, M.R.U. Hrtini, nd A. Azizh, 211. Geltins from three cultured freshwter fish skins otined y liming process. Food Hydrocolloids, 25: Jones, N.R., Uses of geltine in edile products. In A. Wrd nd A. Courts (Eds). The science nd technology of geltine London : Acdemic Press Inc. Jongjreonrk, A., S. Benjkul, W. Visessngun, nd M. Tnk, 26. Skin geltin from igeye snpper nd rownstripe red snpper: Chemicl compositions nd effect of microil trnsglutminse on gel properties. Food Hydrocolloids 2: Krim, A.A. nd R. Bht, 29. Fish geltin: Properties, chllenges, nd prospects s n lterntive to mmmlin geltins. Food Hydrocolloids 23: Kinsell, J. E.,1977. Functionl properties of protein: possile reltionships etween structure nd function in foms. J. Food Chem. 7, Krmer, A., B.A. Twigg, 197. Qulity control for the food industry. The Avi Pulishing Comp., Connecticut. Leuenerger, B. H., Investigtion of viscosity nd geltion Properties of different mmmlin nd fish geltins. Food Hydrocoll, 5(4), Liu, H., D. Li, nd S. Guo, 28. Rheologicl properties of chnnel ctfish (Ictlurus punctus) geltin from fish skins preserved y different methods. LWT-Food Science nd Technology 41: Montero, P., M. D. Fernndez-Dlz, nd M. C. Gomez-Guillen, 22. Chrcteriztion of geltin gels y high pressure. Food Hydrocoll, 16, Moore, S., Automtic recording pprtus use in the chromtogrphy of mino cid. Anl. Chem., 39: Muyong, J.H., C.G.B. Cole nd K.G. Doudu, 24. Extrction nd physico-chemicl chrcteriztion of Nile pech (Ltes niloticus) skin nd one geltin. Food Hydrocolloids, 18: Ockermn, H.W., nd C.L. Hnsen, Glue nd geltine. In. Animl y-product processing nd utiliztion (pp ) Bc Rton, FL: CRC Press. SAS Institute, SAS user s guide. Cry, NC: SAS Institute. Inc. Schrieer, R. nd H. Greis, 27. Geltin Hndook. Theory nd Industril prctice. P Weinheim: Wiley-VCH Verlg GmH nd Co. Kg A. Songchotikunpn, P., Tttiykul, J & Supphol, P. (28). Extrction nd electrospinning of geltin from fish skin. Inter. J. Biol. Mcromol. 42, pp Stevens P.V. (1992). Food Austrli. 44 (7), Trestni, H.S., Y. Mghsoudlou, A. Motmedzdegn, nd A.R. Sdeghi Mhoonk, 21. Optimiztion of physico-chemicl properties of geltin extrcted from fish skin of rinow trout (Onchorhynchus mykiss). Bioresource Technology 11: Urirte-Montoyo, H. M., H. Sntcruz-Orteg, F.J. Cinco-Moroyoqui, O. Rouzud-Sndez, M. Plscenci- Jtome nd J.M. Ezquerr- Bruer, 211. Gint squid skin geltin: chemicl composition nd iophysicl chrcteriztion. Food Reserch Interntionl. 44: Vreltzis, K., D. Koufidis, E. Gvrülidou, E. Ppvergou, nd S. Vsilidou, Effectiveness of nturl rosemry (Rosmrinus officinlis) extrct on the stility of filleted nd minced fish during frozen storge. Z. Leensm. Unters Forsch A., 25: Wssw, J., J. Tng nd X. Gu, 27. Utiliztion of Fish Processin Byproducts in the geltin Industry. Food Rev. Int. 23 (2),

14 Middle Est J. Agric. Res., 4(2): , 215 Yng, H., Y. Wng, M. Jing, J.H. Oh, J. Herring, nd P. Zhou, step optimiztion of the extrction nd susequent physicl properties of chnnel ctfish (Ictlurus puncttus) skin geltin. Journl of Food Science 72(4): Zhou, P. nd J. M. Regenstein, 27. Comprison of Wter Gel Desserts from Fish Skin nd Pork Geltins Using Instrumentl Mesurements. J. Food Sci. 72 (4), Zhou, P., J. M. Steven, nd J. M. Regenstein, 26. Properties of Alsk Pollock skin geltin: A comprison with Tilpi nd Pork skin geltins. J. Food Chem. 71(6),