Pkistn Jurnl f Nutritin 9 (11): 1088-1093, 2010 ISSN 1680-5194 Asin Ntwrk fr Sintifi Infrmtin, 2010 Qulity Attriuts f Sy-yghurt During Strg Pri Mnhl Mhmm Dfll Osmn n Kml Aw Al Rzig Dprtmnt f F Sin n Thnlgy, Fulty f Agriultur, Al-Zim Al-Azhri Univrsity, P.O. Bx 1432, Khrtum Nrth 13311, Sun Astrt: Th utiliztin f syn milk in mnufturing yghurt in Sun ws invstigt. Syn milk ws prpr frm grin syn ss. Fur smpls f sy yghurt prut wr us, nmly smpl A) 100% symilk (smpl B) 1:1 symilk: w milk), smpl C (2:1 symilk: w milk) n smpl D (1:2 symilk: w milk). Th prpr sy yghurt smpls wr str t rfrigrtr tmprtur (10±2 C) fllw y nlyss t 0, 5, 10, 15 n 20 ys intrvls. Th hmil mpsitins f syn milk us wr th ttl slis (13.15%), prtin (7.64%), ft (2.75%), ph-vlu (6.70) n titrtl iity (0.20%).Th typ f milk signifintly (p<0.05) fft th ph-vlu f th sy yghurt. Smpl A ws th highst (4.50), smpl D th lwst (3.30) whil smpl B n smpl C wr t n intrmit psitin (3.50 n 3.70 rsptivly). Strg pri signifintly (p<0.05) fft th ph-vlu f sy yghurt, th highst vlu (4.30) ws tin t th ginning f th strg pri, whil th lwst vlu (3.00) t th n. Th typ f milk signifintly (p<0.05) fft th titrtl iity f th sy yghurt. Smpl A ws th lwst (1.12%), Smpl D ws th highst (2.50%), whil smpls B n C wr in n intrmit psitin. Strg pri signifintly (p<0.05) fft th titrtl iity f sy yghurt. Th lwst titrtl iity (1.21%) ws tin t th ginning f strg pri n th highst (2.60%) t th n. Th typ f milk signifintly (p<0.05) fft th whying ff f th sy yghurt. Smpl A ws th highst (2.70 ml), smpl D ws th lwst (1.70 ml), whil smpls B n C wr t n intrmit psitin. Strg pri signifintly (p<0.05) fft th whying ff f sy yghurt. Th lwst whying ff (0.00 ml) ws tin t th ginning f strg pri n th highst (4.00 ml) t th n. Th hmil nlyss f sy yghurt smpls t zr tim prssing, smpl A) 100% symilk (ws th highst (31.20%) fr ttl slis n prtin ntnt (16.70%),whil smpl D (1:2 symilk: w milk) ws th lwst (15.70%) fr ttl slis n prtin ntnt) 11.25). Smpl B n C wr t n intrmit psitin. Smpl A ws th lwst (2.20%) fr ft ntnt, smpl D ws th highst (3.25%),whil smpls Bn C upy n intrmit psitin. Th snsry vlutin signifintly (p<0.05) fft y Th typ f milk n strg pri rvl tht, th st sr (p<0.05) in pprn (4.38), flvur (4.10), txtur (4.22) n vrll ptility (4.28) in smpl D(1:2 symilk: w milk), th wrst ws rr y smpl A (Symilk 100%) fr pprn (2.68), flvur (3.48), txtur (3.36) n vrll ptility (3.44). Th thr smpls wr t n intrmit psitin. It ws fun tht 10 ys strg pri t rfrigrtr tmprtur (10±2 C) ws quit stisftry t ttin g qulity sy yghurt. Ky wrs: Sy milk, yghurt, strg, w milk INTRODUCTION Vgtl milk is prpr frm f grins suh s sy n, ssm n grunnut. Syn (Glyin mx), plnt prtin whih is hpr ul srv s n ltrntiv t w milk. Syn milk is rihr in prtin thn mst niml milk. It ntins up t 40% prtin mpr with 1.0% t 5.6% prtin ntnt f mst niml milk (Burtn, 1985). Symilk is prss frm syn. Intk f frmnt symilk imprvs th systm in th intstinl trt y inrsing th munt f pritis (Chng t l., 2005). Syn n its rivts rprsnt n xllnt sur f high qulity prtin, with lw ntnt f sturt ft n grt munt f itry fir n itiv mpnnts lik th isflvns. Symilk n its frmnt pruts nstitut n ltrntiv fr lts intlrnt ppl. In this wy, sy yghurt ul suitl vhil fr irn frtifitin, sin it hs high nutritinl vlu n lwst. Hwvr, lium ntnt f symilk is lwr tht fun in w s milk, ing nssry th itin f this minrl t imprv its nutritinl prprtis. Th jtiv f this wrk is t prpr th milk frm syn ss n t stuy thir ffts n qulity f Suns sy yghurt uring strg pri. Crrspning Authr: Mnhl Mhmm Dfll Osmn, Dprtmnt f F Sin n Thnlgy, Fulty f Agriultur, Al-Zim Al-Azhri Univrsity, P.O. Bx 1432, Khrtum Nrth 13311, Sun 1088
Pk. J. Nutr., 9 (11): 1088-1093, 2010 MATERIALS AND METHODS Th ss wr tin frm th ll mrkt. Th strtr ultur Ltillus ulgrius n Strptus thrmphilus wr tin frm Khrtum Diry Pruts Cmpny Lt. Plsti ups (250 ml vlum) wr purhs frm rtilrs in th ll mrkt. Frsh w milk ws tin frm th Univrsity f Sun Diry Frm (Shmt). Prprtin f symilk: Syn milk ws prpr y sking krnls in 0.5% sium irnt slutin fr 16-18 h, rin, wsh with tp wtr, grin, stp fr 4-5 h in tp wtr (100 g syn mix with 100 ml tp wtr) n filtrt thrugh hs lth t tin th symilk. Prprtin f sy-yghurt: Fur smpls (A, B, C n D) wr slt in whih symilk ws kpt in qul vlums ftr ing filtr frm impuritis. Smpl (A) 100% symilk, smpl (B)1:1 symilk: w milk, smpl 2:1 symilk: w milk n smpl (D) 1:2 symilk: w milk. Th vlums wr psturiz t 85 C fr 10 min n thn l t 45 C. Strtr ultur 3% f th milk vlum ws in th frm f (Strptus thrmphilus n Ltillus ulgrius). Th milk mixtur ws pl in 250 ml ups n kpt in n inutr t 45 C fr 3-6 h. Th ups wr trnsfrr t rfrigrtr n str in tmprtur f 10±2 C fr 0, 5, 10, 15 n 20 ys intrvls. Th Anlyss wr rri fr physihmil, rhlgil n snsry vlutin. Chmil nlyss: Th ph-vlus f smpls wr trmin ring t Nwlnr n Athrtn (1964), whil th titrtl iity, ttl slis, prtin n ft ntnt wr trmin ring t AOAC (1995). Rhlgil prprtis: Whying-ff ws msur y suking ff th wtr frm th surf f th ur n pur in grut ylinr. Snsry vlutin: Th snsry vlutin ws prfrm y 10 untrin pnlists using prur ring t Ihkrny n Ngy (1985). Sttistil nlyss: Dt ws sujt t sttistil nlyss using Sttistil Anlysis Systm prgrm (SAS, 1988). RESULTS AND DISCUSSION Syn milk: Th rsults f hmil prprtis f sy milk wr f ttl slis (13.15%), ph-vlu (6.70), titrtl iity (0.20%), prtin ntnt (7.64%) n ft ntnt (2.75%). Tuitmwng t l. (1993) fun tht, th symilk hs sirl hrtristis s n ingrint fr mking sy yghurt us f its high sli ntnt (Mriguhi t l., 1961). Angls n Mrth (1971) fun titrtil iity f 0.23-0.25% r ph f 5.7. Wlf, (1978) nlu 60-70% f th ttl prtin in th syn is str in th prtin is. Dshpn t l. (2008) fun tht, th symilk ntins ttl slis (9.8%), ft (2.6%), prtin (5.8%), ph vlu (6.0) n sh (0.6%). L t l. (1990) stt th vritin in th rsults t th rigin f syn n t th prssing nitin. Chmil prprtis f sy yghurt ph-vlu: Th typ f milk ws signifintly (p<0.05) fft ph-vlus f th sy yghurt (Tl 1). Smpls D (1:2 symilk: w milk) ws th lwst (3.30) n smpl A) 100% symilk (th highst (4.50), whil smpls B (1:1 symilk: w milk) n C (2:1 symilk: w milk) wr t n intrmit psitin (3.50 n 3.70) rsptivly. Strg pri signifintly (p<0.05) fft th phvlus, whr thy rs grully till th n f strg (Tl 2 n Fig. 1). Th highst ph-vlu (4.30) ws tin t th ginning f th strg pri, whrs th lwst (3.00) t th n. Sugimt n Vn Burn (1970) n Bun (1988) fun tht, th ph-vlu f sy yghurt t 5.00. Mriguhi t l. (1961) stt high ptimum ph-vlus f sy yghurt vri frm 5.0-6.0. Tl 1: Efft f typ f milk n ph-vlu*, titrtl iity* n whying ff* f sy-yghurt Smpls ---------------------------------------------------------------------------------------- Prmtrs A B C D LSD0.05 SE± ph-vlu 4.50±0.08 3.50±0.04 3.70±0.06 3.30±0.02 0.8297 0.2633 Titrtl iity (% lti i) 1.12±0.01 1.70±0.04 1.41±0.03 2.50±0.05 0.1151 0.03651 Whying-ff (ml) 2.70±0.06 2.40±0.04 2.50±0.05 1.70±0.02 0.1819 0.05774 *Mns±SD. Vlus hving iffrnt suprsript lttr in rws r signifintly iffrnt (p<0.05). A = Symilk 100%; B = Symilk: w milk 1:1; C = Symilk: w milk 2:1; D = Symilk: w milk 1:2 Tl 2: Efft f strg pri n ph-vlu*, titrtl iity* n whying ff* f sy-yghurt Strg pri (ys) --------------------------------------------------------------------------------------------------- Prmtrs 0 5 10 15 20 LSD0.05 SE± ph-vlu 4.30±0.09 3.90±0.08 3.70±0.06 3.30±0.04 3.00±0.02 0.1819 0.05774 Titrtl iity (% lti i) 1.21±0.01 1.52±0.02 2.00±0.04 2.34±0.06 2.60±0.08 0.1151 0.03651 Whying-ff (ml) 0.00±0.00 1.80±0.01 2.40±0.03 3.00±0.05 4.00±0.07 1.156 0.3670 *Mns±SD. Vlus hving iffrnt suprsript lttr in rws r signifintly iffrnt (p<0.05) 1089
Pk. J. Nutr., 9 (11): 1088-1093, 2010 Fig. 3: Efft f strg pri n whying-ff f sy- yghurt Fig. 1: Efft f strg pri n ph-vlu f syyghurt strg. Th highst vlu (4.00 ml) ws tin t th n, whil th lwst (0.00 ml) t th ginning f th strg pri. Luy t l. (2000) fun tht, stilizrs r mmnly us in ultur pruts t ru why sprtin. Fig. 2: Efft f strg pri n titrtl iity (% lti i) f sy-yghurt Titrtl iity: Th typ f milk ws signifintly (p<0.05) fft titrtl iity (Tl 1). Smpl A (100% sy milk) ws th lwst (1.12%), Smpls D (1:2 symilk: w milk) th highst (2.50), whil smpl B n C wr t n intrmit psitin (1.70% n 1.41, rsptivly). Strg pri signifintly (p<0.05) fft titrtl iity f Suns sy yghurt smpls (Tl 2 n Fig. 2). Titrtl iity inrs grully till th n f strg. Th highst vlu (2.60%) ws tin t th n, whil th lwst (1.21%) t th ginning f th strg. Mths fr th rutin f th fltulnt sugrs, rffins n sthys in symilk n syn pruts hv n xtnsivly invstigt (Mitl t l., 1973; Pinthng t l., 1980,; Bun, 1988; Bun t l., 1990,). Mitl t l. (1973) stt th tivity f th nzym lph-gltsis (EC 3.2.1.22) in sm lti i tri. Th sy yghurt ntins ligshris suh s rffins, sthys pru uring th frmnttin prss. Whying ff: Th typ f milk ws signifintly (p<0.05) fft th whying ff (Tl 1). Smpl A ws th highst (2.70 ml), smpl D th lwst (1.70%), whil smpl B n C wr t n intrmit psitin (2.40 ml n 2.50 ml rsptivly). Strg pri signifintly (p<0.05) fft whying ff f Suns sy yghurt smpls (Tl 2 n Fig. 3). Th whying ff inrs grully till th n f Chmil mpsitin f sy yghurt smpls Ttl slis: Th typ f milk signifintly (p<0.05) fft th ttl slis f th sy yghurt. Smpl A) 100% symilk (rr th highst ntnt f ttl slis (31.20%) mpr with smpl D (1:2 symilk: w milk), tht gv th lwst (15.70%). Smpls B (21.80%) n C (29.40%) shw n intrmit psitin (Tl 3). Tuitmwng t l. (1993) fun high ttl sli ntnt f prss sy yghurt rng frm 56.02-61.12%. Th symilk hs sirl hrtristis s n ingrint fr mking sy yghurt us f its high sli ntnt. Tmim n Rinsn (1999) fun th ttl slis f prss sy yghurt rng frm 34.2-44.4%. Prtin ntnt: Th typ f milk ws signifintly (p<0.05) fft th prtin ntnt f sy yghurt (Tl 3). Smpl A ws th highst (16.70%), Smpl D th lwst (11.25%), whil smpl B n Smpl C, upi n intrmit psitin (13.00% n 14.80%, rsptivly). Burringtn (2000) nti tht, sy prtins r high in th min is glyin n rginin. Ft ntnt: Th typ f milk ws signifintly (p<0.05) fft ft ntnt f sy yghurt. Smpl D (Symilk: w milk 1:2) ws th highst (3.25%) whrs smpl A (Symilk 100%) ws th lwst (2.20%). Whil smpl B n C shw n intrmit psitin (3.00% n 3.20, rsptivly). Tmim n Rinsn (1999) rprt tht, th ft ntnt f prss sy yghurt vri frm 1.2-2.2%. Frimn n Brnn (2001) fun tht, sy r sy prut ntining sy prtin tht mts rquirmnts inluing lw sturt ft n lw hlstrl with minimum f 4.25% f sy prtin. Burringtn (2000) nti tht, sy prtins r high in th min is glyin n rginin, whih rs hlstrl n lwr ft lvls. Dshill t l. (1990) stt lw hlstrl sy milk yghurt. 1090
Pk. J. Nutr., 9 (11): 1088-1093, 2010 Tl 3: Chmil mpsitin* (%) f sy-yghurt Smpls ---------------------------------------------------------------------------------------------------- Prmtrs A B C D LSD0.05 SE± Ttl slis ntnt 31.20±0.09 21.80±0.02 29.40±0.06 15.70±0.04 0.1819 0.05774 Ft ntnt 2.20±0.01 3.00±0.01 3.20±0.46 3.25±0.01 0.3728 0.1183 Prtin ntnt 16.70±0.48 13.00±0.26 14.80±0.39 11.25±0.15 0.1409 0.04472 *Mns±SD. Vlus hving iffrnt suprsript lttr in rws r signifintly iffrnt (p<0.05). A = Symilk 100%; B = Symilk: w milk 1:1; C = Symilk: w milk 2:1; D = Symilk: w milk 1:2 Tl 4: Efft f typ f milk n qulity ttriuts* f sy-yghurt Smpls -------------------------------------------------------------------------------------------------- Qulity ttriut A B C D LSD0.05 SE± Apprn 2.68±0.01 3.37±0.04 2.86±0.02 4.38±0.05 0.3728 0.1183 flvur 3.48±0.02 3.58±0.05 3.36±0.04 4.10±0.06 0.0814 0.0258 Txtur 3.36±0.01 3.56±0.03 3.46±0.02 4.22±0.04 0.0006 0.0002 Ovrll ptility 3.44±0.03 3.88±0.05 3.68±0.04 4.28±0.07 0.0006 0.0002 *Mns±SD. Vlus hving iffrnt suprsript lttr in rws r signifintly iffrnt (p<0.05). A = Symilk 100%; B = Symilk: w milk 1:1; C = Symilk: w milk 2:1; D = Symilk: w milk 1:2 Tl 5: Efft f strg pri n qulity ttriuts* f sy-yghurt Strg pri (ys) ------------------------------------------------------------------------------------------------------------ Qulity ttriut 0 5 10 15 20 LSD0.05 SE± Apprn 3.26±0.01 3.52±0.03 3.86±0.05 3.62±0.04 2.28±0.02 0.0006 0.0002 Flvur 3.58±0.03 4.04±0.05 4.30±0.06 4.10±0.05 3.68±0.02 0.0006 0.0002 Txtur 3.64±0.02 3.88±0.03 4.07±0.04 3.86±0.03 3.62±0.02 0.0006 0.0002 Ovrll ptility 3.76±0.03 4.10±0.04 4.30±0.06 4.10±0.04 3.68±0.02 0.1409 0.0447 *Mns±SD. Vlus hving iffrnt suprsript lttr in rws r signifintly iffrnt (p<0.05) th frmnt syn milk ws mr ptl thn thrs n ws prfrr in trms f lur. Cun t l. (2005) fun tht, th sy yghurt frmnt with strtr ultur imprv lur n frtifi with spilly nturl fruit juis t mt th rquirmnt f nsumrs. Fig. 4: Efft f strg pri n pprn f syyghurt Orgnlpti qulity f Suns sy yghurt smpls Apprn: Th typ f milk ws signifintly (p<0.05) fft th pprn f yghurt. Tl 4 shws th pprn sr f Suns sy yghurt. Smpl D (symilk: w milk 1:2) signifintly (p<0.05) sur th st pprn (4.38). Smpl B n C in n intrmit psitin (3.37 n 2.86, rsptivly). Th wrst (2.68) rr y smpl A (symilk 100%). Strg pri signifintly (p<0.05) fft th pprn f th sy yghurt smpls (Tl 5 n Fig. 4). Th st srs (3.86) wr tin t y 10 n th wrst (2.28) t th n f th strg pri. Pinthng t l. (1980); Nilsn (1985) rprt tht, Flvur: Tl 5 illustrt th flvur sr f th Suns sy yghurt. Smpl D m with (Symilk: w milk 1:2) signifintly (p<0.05) sur th st flvur (4.10), fllw y smpl B n C. Th wrst flvur (3.48) ws rr y smpl A (Symilk 100%). Strg pri signifintly (p<0.05) fft th flvur f th sy yghurt smpls (Fig. 5). Th st sr (4.30) ws tin t y 10 n th wrst (3.58) t th ginning f th strg pri. Lti i frmnttin ru ny flvurs in syn pruts (Pinthng t l., 1980,; Bun, 1988; Bun t l., 1990). Liu (1997) fun tht, frmnttin f symilk ffrs nt nly mns f prsrving symilk ut ls pssiility fr mifying r imprving flvur. Cun t l. (2005) mntin tht, th sy yghurt frmnt with strtr ultur imprv tst n frtifi with spilly nturl fruit juis t mt th rquirmnt f nsumrs. 1091
Pk. J. Nutr., 9 (11): 1088-1093, 2010 Fig. 5: Efft f strg pri n flvur f sy-yghurt Fig. 6: Efft f strg pri n txtur f sy-yghurt Fig. 7: Efft f strg pri n vr ll ptility f sy-yghurt Txtur: Th typ f sy milk ws signifintly (p<0.05) fft th txtur f yghurt. Smpl D signifintly sur th st txtur (4.22). Smpls B n C rnk in n intrmit psitin (3.56 n 3.46, rsptivly). Th wrst txtur (3.36) rr y smpl A (Tl 5). Strg pri signifintly (p<0.05) fft th txtur f th sy yghurt smpls (Fig. 6). Th st srs (4.07) wr tin t y 10 n th wrst (3.62) wr tin t th n f th strg. Liu (1997) stt tht, frmnttin f symilk ffrs nt nly mns f prsrving symilk ut ls pssiility fr mifying r imprving txtur. Luy t l. (2000) fun tht, stilizrs r mmnly us in ultur pruts t ntrl txtur sy yghurt. Ovrll ptility: Th vrll ptility f Suns sy yghurt smpls prpr frm syn milk wr fft y th typ f milk (Tl 5). Smpl D m with (symilk:w milk 1:2) signifintly sur th st ptility (4.28), fllw y smpl B (3.88) n C (3.68). Th wrst (3.44) ws rr in smpl A m with 100% symilk. Strg pri signifintly (p<0.05) fft th vrll ptility f th sy yghurt smpls (Fig. 7). Th st sr (4.30) ws tin t y 10 n th wrst (3.68) t th n f th strg pri. Orgnlpti qulity f frmnt pruts is irtly rlt t lvls f n-pntnl n n-hxnl, th frm ing pru y S. thrmphilus n th lttr ing nturlly prsnt in sy milk (Pinthng t l., 1980). Pinthng t l. (1980) fun tht, frmnt sy milk ntin lss n-hxnl thn th unfrmnt symilk. Bny flvurs, hlkinss n stringnt hrtristis hv n rprt s th mjr snsry ttriuts fun y snsry vlutin f sy yghurt smpls y trin pnls (Tuitmwng t l., 1993). REFERENCES Angls, A.G. n E.H. Mrth, 1971. Grwth n tivity f lti i tri in symilk. I. Grwth n i prutin. J. Milk F Thnl., 34: 30. th AOAC, 1995. Offiil Mths f Anlysis. 14 En., Assitin f ffiil nlytil hmists, Wshingtn, DC. Bun, M.A., 1988. An nginring mirilgy n snsry stuy f yghurt frm sy milk. Ph.D. Dissrttin. Knss Stt Univrsity, Mnhttn. Bun, M.A., L.E. Eriksn n D.Y.C. Fung, 1990. Crhyrt utiliztin n grwth kintis in th prutin f yghurt frm symilk. Prt II: Exprimntl n prmtr stimtin rsults. J. F Pr. Prsrv., 14: 179-204. Bun, M.A., L.E. Eriksn, D.Y. Fung n I. Jn, 1990. Crhyrt utiliztin n grwth kintis in th prutin f yghurt frm symilk. Prt I: Exprimntl mths. J. F. Pr. Prsrv., 14: 135-153. Burringtn, K., 2000. Nutritinl n nfiil ingrints. F Prut Dsing, pp: 1-12. Burtn, J.W., 1985. Bring syn fr imprv prtin qulity n quntity. In: Pring f th 3r Wrl Syn Rsrh Cnfrn, (Shils R E.). Wst Viw Prss, wlr, Clr pp: 136-165. Chng, I.C., H.F. Shng, T. Lin, T.H. Wng n S.H. Lin, 2005. Efft f frmnt symilk in th intstinl tri systm. Wrl J. Gstrntrl., 11: 1225-1227. Cun, M., L. Ci, M. Hlguin n M. Quizn, 2005. Frmntin lti un mzl i sy lh v utilizn luls lirs inmvilizs. Mmris Sgun simpsi sr ifris. Cit frm PDF (2005). 1092
Pk. J. Nutr., 9 (11): 1088-1093, 2010 Dshill, K.E., S.R. Singh, O. Nkym, H.O. Ogunip n C.N. Akm, 1990. Syn rsrh t IITA. GLIP Rsrh Mngrph N. 1In. Dshpn, S., P. Brgl n K. Jh, 2008. Suitility f symilk fr vlpmnt f shrikhn. J. F Si. Thnl., 45: 284-286. Frimn, M. n D.L. Brnn, 2001. Nutritinl n hlth nfits f sy prtins. J. Agri. F Chm., 49: 1069-1086. Ihkrny, N.I. n P.O. Ngy, 1985. Intgrt f, Si. n Th. fr Trpis. Mmilln Pulishr. L, S.Y., V.C. Mrr n A. S, 1990. Cmprisn f milk s n sy milk yghurt. J. F Si., 55: 532-536. Liu, K., 1997. Chmistry n nutritinl vlu f syn mpnnts. In syns: Chmistry, thnlgy n utiliztin. Liu K. Chpmn n Hll: Nw Yrk, pp: 25-113. Liu, K., 1997. Syns: Chmistry, thnlgy n utiliztin. Intrntinl Thmpsn Pulishr. Luy, J.A., M. Tmhn, H. Singh n P.A. Munr, 2000. Rhlgil prprtis f milk gls frm y mintin f rnnt n glun-ltn. J. Diry Rs., 67: 415-427. Mitl, B.K., R.S. Shllnrgr n K.H. Stinkrus, 1973.Alph-gltsis tivity f ltilli. Appl. Miril., 26: 783-788. Mriguhi, S., H. Ishikw, R. U n M. Hyshi, 1961. Stuis n rgni is in syns n ftt syns. Hkk Kgku Zsshi, 39: 237-243. Nwlnr, J.A. n H.V. Athrtn, 1964. Th hmistry n tsting f iry pruts, 3r En., (rvis), Olsn-Pulishing C., Milwuk, Wisnsin. Nilsn, N.C., 1985. Strutur f sy prtins. Ch. II. In nw prtin fs, vl. 5, s strg prtins, A.M. Altshul n H.L. Wilk (Es.). Ami prss, In. Orln, FL. Pinthng, R., R. Mr n J. Rthwll, 1980. Th vlpmnt f sy-s yghurt: I. Ai prutin y lti i tri. J. F. Th., 15: 647-652. Pinthng, R., R. Mr n J. Rthwll, 1980. Th vlpmnt f sy- s yghurt. II. Snsry vlutin n nlysis f vltils. J. F Thnl., 15: 653-660. SAS, 1988. Sttistil Anlysis Systm Institut, In., Cry, NC. Sugimt, H. n J.P. Vn Burn, 1970. Rmvl f ligshris frm sy milk y n nzym frm Asprgillus siti. J. F Si., 35: 655-660. Tmim, A.K. n R.K. Rinsn, 1999. Yghurt Sin n Thnlgy. Wh pulishing Lt n CRC prss LLC. B Rtn, Flri, pp: 619. Tuitmwng, P., L.E. Eriksn, D.Y. Fung, C.S. Stsr n S.K. Prng, 1993. Snsry nlysis f sy yghurt n frzn sy yghurt pru frm rpi hyrtin hyrthrml k sy milk. J. F Qulity, 16: 223-239. Wlf, W.J., 1978. Purifitin n prprtis f th prtins. Ch. 4 in syns: hmistry n n thnlgy. Vl. 1 prtin, rvis 2 printing. A.K. Smith n S.J. Cirl. (Es.), AVI pulishing C., In., Wstprt, CN. 1093