Whey protein concentrate gels with different sucrose content: instrumental texture measurements and sensory perception

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1 Ymul, Digo K. ; Glmrini, Mr V. ; Lupno, Cili E. ; Zmor, Mrí C. Why protin onntrt gls with diffrnt suros ontnt: instrumntl txtur msurmnts nd snsory prption L vrsión dfinitiv d st rtíulo stá publid n Intrntionl Diry Journl, Vol. 28, 2013 Est doumnto stá disponibl n l Bibliot Digitl d l Univrsidd Ctóli Argntin, rpositorio instituionl dsrrolldo por l Bibliot Cntrl Sn Bnito Abd. Su objtivo s difundir y prsrvr l produión intltul d l Instituión. L Bibliot pos l utorizión dl utor pr su divulgión n lín. Cómo itr l doumnto: Ymul, D. K., Glmrini, M. V., Lupno, C. E. y M. C. Zmor Why protin onntrt gls with diffrnt suros ontnt : instrumntl txtur msurmnts nd snsory prption [n lín]. Posprint dl rtíulo publido n Intrntionl Diry Journl 28(1). Disponibl n: (S romind indir fh d onsult l finl d l it. Ej: [Fh d onsult: 19 d gosto d 2010]).

2 Aptd Mnusript Why protin onntrt gls with diffrnt suros ontnt: instrumntl txtur msurmnts nd snsory prption Digo K. Ymul, Mr V. Glmrini, Cili E. Lupno, Mri C. Zmor PII: S (12)00163-X DOI: /j.idiryj Rfrn: INDA 3404 To ppr in: Intrntionl Diry Journl Rivd Dt: 6 Fbrury 2012 Rvisd Dt: 9 August 2012 Aptd Dt: 10 August 2012 Pls it this rtil s: Ymul, D.K., Glmrini, M.V., Lupno, C.E., Zmor, M.C., Why protin onntrt gls with diffrnt suros ontnt: instrumntl txtur msurmnts nd snsory prption, Intrntionl Diry Journl (2012), doi: /j.idiryj This is PDF fil of n unditd mnusript tht hs bn ptd for publition. As srvi to our ustomrs w r providing this rly vrsion of th mnusript. Th mnusript will undrgo opyditing, typstting, nd rviw of th rsulting proof bfor it is publishd in its finl form. Pls not tht during th prodution pross rrors my b disovrd whih ould fft th ontnt, nd ll lgl dislimrs tht pply to th journl prtin.

3 Why protin onntrt gls with diffrnt suros ontnt: instrumntl txtur msurmnts nd snsory prption Digo K. Ymul *, Mr V. Glmrini b,, Cili E. Lupno, Mri C. Zmor b, Cntro d Invstigión y Dsrrollo n Criotnologí d Alimntos (CIDCA), Fultd d Cinis Exts, UNLP - CCT L Plt - CONICET, 47 y 116, 1900 L Plt, Argntin. b Consjo Nionl d Invstigions Cintífis y Ténis (CONICET) Av. Rivdvi 1917 (C1033AAJ) Bunos Airs, Argntin. Fultd d Cinis Agrris Pontifii Univrsidd Ctóli Argntin (UCA) Cp. Grl. Rmón Frir 183 (C1426AVC) Bunos Airs, Argntin. *Corrsponding uthor: Tl.: E-mil ddrss: [email protected] (D. K. Ymul) 24 25

4 Abstrt Corrltions btwn instrumntl txtur, snsory txtur nd swtnss prption wr studid in why protin onntrt (WPC) gls t diffrnt ph (4 nd 7), suros (0-40%, w/w) nd why protin (10-20%, w/w) ontnt. Th prsn of suros modifid th strutur of WPC gls, minly t ph 4, mking th gl strutur mor homognous nd with smllr pors. Suros lso inrsd th solid bhviour of gls, thir wtr holding pity, hrdnss nd dhsivnss. Swtnss prption drsd s protin onntrtion inrsd, nd ws highr in gls t ph 4 thn in gls t ph 7. A good orrltion ws obtind btwn th instrumntl nd snsory ttributs hrdnss, ohsivnss nd lstiity.

5 Introdution Food txtur is mjor ritrion of food qulity, sin it influns onsumr ptn of foodstuffs (Szzsnik & Khn, 1971). In mny produts, fts nd sugrs hv long plyd n importnt rol in txtur. Howvr, nw hlth trnds mong onsumrs dmnd foods rdud in ths omponnts, but, ndlss to sy, not rdud in tst or txtur. Thus, th dvlopmnt of foodstuffs with low sugr nd ft ontnt, but with th sm, or vn bttr, snsory qulity, hs bom hllng for th food industry. Why protin onntrts (WPCs) ontribut to nhn ttributs suh s rminss, txtur or wtr binding in diffrnt food systms (Johnson, 2000; Ohms, Mrshll, & Hymnn, 1998).Whn why protin (WP) gltion tks pl undr onditions of ltrostti rpulsion btwn protin moluls, fin-strndd struturs r obtind. On th othr hnd, t ph los to th isoltri point, gls r opqu with ors prtiult strutur (Clrk, Judg, Rihrds, Stubbs, & Suggt, 1981; Stding, Lngton, & Hrmnsson, 1993). Morovr, th bhviour of WP is vry diffrnt undr id onditions or t nutrl ph. Non-ovlnt intrtions (vn dr Wls ttrtiv fors, hydrogn bonds nd ltrostti nd hydrophobi intrtions) will dtrmin th strutur of gls t id ph, whil t nutrl ph intrmolulr sulphydryl-disulphid intrhng rtions r fvourd (Lupno, Dumy, & Chftl, 1992; Shimd & Chftl, 1988; Ymul & Lupno, 2003). Protin onntrtion lso plys ky rol in gl formtion. Diffrnt txturs r obtind within th onntrtion rng of 7% to 20% (w/w). At lowr onntrtions (<7%, w/w) th gl is not formd (Huffmn, 1996, Tng, MCrthy, & Munro, 1995), nd t onntrtions bov 20% (w/w) it is diffiult to obtin homognous disprsion suitbl for gltion.

6 Th mirostrutur of gl, whthr it is strndd or prtiult, will dirtly influn its snsory prption. Strndd gls r springy nd brkdown into lrg prtils with miniml rls of fluid during mstition. On th othr hnd, prtiult gls rls dttbl mount of fluid nd brk down into smll prtils tht dhr to th tth during hwing (Gwrtny, Lrik, & Fogding, 2004). In ddition, txturl hrtristis of food mtris influn th prption pross by filitting (or not) th rls of tstnts, thir mixing with sliv nd thir intrtion with gusttory rptors. In fluid mtrix, tstnts r immditly mixd with sliv nd rh th gusttory rptors quikly (Byrri, Rivs, Izquirdo, & Costll, 2007). In ontrst, in smi-solid foods, suh s WP gls, thy r rlsd t diffrnt rts dpnding on th intrtions with th gl nd th hwing pross, i.., th brkdown rt. It is for this rson tht svrl uthors hv ttmptd to orrlt swtnss with txtur in liquid nd solid foods. Lthuut, Brossrd, Roussu, Boussu, nd Gnot (2003) studid th fft of suros on th swtnss-txtur intrtions in rrgnn gls. DMrs nd Ziglr (2001) nd Moritk nd Ntio (2002) found tht swtnss in gltin gls drsd s gltin ontnt inrsd. Holm, Wndin, nd Hrmnsson (2009) invstigtd th hrdnss of ptin gls on th swtnss prption. Byrri t l. (2007) studid th swtnss prption in rrgnn nd gur gum gls. All ths studis gr tht th hrdr th gls, th lowr th swtnss prption. In ddition, numrous uthors hv studid th ombintion of suros WP gl (Boy, Klb, Alli, & M, 2000; Dirkx & Huyghbrt, 2002; Kulmyrzv, Brynt, & MClmnts, 2000); howvr, th or of thir rsrh ws fousd on th physiohmil proprtis without onsidring th snsory txtur prption. Th im of this work ws to study th orrltions btwn instrumntl nd snsory txtur in WPC gls t diffrnt ph lvls, suros nd WP ontnt. Rsults ould b usful in dtrmining

7 th bst ondition to rt low sugr ontnt produt with n ttrtiv txtur hving th dvntg of th nutritionl nd funtionl proprtis of WP Mtrils nd mthods 2.1. Gl prprtion WPC ws gift from Arl Foods Ingrdints S.A. (Mrtinz, Bunos Airs, Argntin). WPC ontind 77.71% (w/w) protin (N 6.38), 5.74% (w/w) moistur, 2.77% (w/w) sh, 3.83% (w/w) lipids nd 9.95% (w/w) ltos (stimtd by diffrn). Commril suros (Ldsm, Ingnio Ldsm SA, Jujuy, Argntin) ws lso usd. All hmils mployd wr of nlytil grd. Gls wr prprd ording to th thniqu dsribd in prvious rports (Cssini, Ymul, Conforti, Pérz, & Lupno, 2011; Ymul & Lupno, 2003, 2005). A ompltly rndomisd ftoril dsign ws obtind using th Sttgrphis plus 5.1 softwr (SttPoint In., USA). Th thr ftors wr: ph, WP onntrtion nd suros onntrtion. Th lvls of th ftors wr inorportd into th dsign nd wr nlysd in 30 ombintions. For gl omposition nd ph s Tbl Instrumntl vlution Confol lsr snning mirosopy ws rrid out s dsribd by Cssini t l. (2011). Th following smpls wr ssyd: suros ontnt, 0%, 20% nd 40% (w/w); ph of gls, ph 4 nd ph 7; protin ontnt of ll gls, 10% (w/w) Lrg dformtion msurmnts wr rrid out s dsribd in prvious works (Cssini t l., 2011; Ymul, & Lupno, 2003, 2005), xpt for th hrdnss nd Young s

8 modulus tht wr obtind by omprssing th smpl down to 20% of th originl hight. Smpl hrdnss ws dfind s th hight of th pk of th for vrsus tim/dformtion urv nd th Young s modulus ws lultd from th initil slop (linr rgion) of th sm urv. Th vrg (± stndrd dvition) of t lst thr dtrmintions ws lultd for h typ of smpl. Wtr holding pity (WHC) ws prformd s dsribd in prvious works (Cssini t l., 2011; Ymul & Lupno, 2003, 2005). WHC ws xprssd s prntg of th initil wtr rmining in th gl ftr ntrifugtion. Vlus r th vrg (± stndrd dvition) of t lst two dtrmintions Snsory vlution Sorting tsk A pnl of 16 ssssors, nmly fml studnts from Fultd d Cinis Agrris, Pontifii Univrsidd Ctóli, Argntin; yrs old, nlysd th smpls in duplit in two sssions by pplying sorting tsk with dsription (Llivr, Chollt, Abdi, & Vlntin, 2008). Assssors wr highly fmilir with disrimintion tsting nd wr trind in dsriptiv mthods in th vlutd smpls. Tsting took pl in individul booths kpt t 22 ± 2 C, undr dylight (6,500 K). Tn grms of smpl wr pld in thr digit odd ups nd prsntd in rndom ordr. Minrl wtr ws providd for orl rinsing btwn smpls. Assssors wr llowd to tst s mny smpls s thy wishd nd in ny ordr; thy wr fr to mk s mny groups s thy wntd. Finlly, thy wr skd to dsrib h group of smpls by using th ttribut dfinitions shown in Tbl nd/or ny othr onpt thy wntd. 138

9 Swtnss intnsity quntifition A pnl of 14 ssssors, who prtiiptd in suh sorting tsk, ws trind to quntify th swtnss intnsity of th smpls in duplit. First, thy ordrd th smpls for swtnss intnsity hving two suros solutions (5 nd 15%, w/w) s stndrds. On th smpls wr ordrd, ssssors msurd swtnss lvls on 15 m lin sl Txtur profil Th sm pnl of 14 ssssors nlysd th txtur of th sltd smpls by following Quntittiv Dsriptiv Anlysis (QDA) mthod (Ston & Sidl, 1993). Thy rivd thr trining sssions (on-hour long h), during whih, with th id of stndrds, thy lrnt how to msur th ttributs listd in Tbl 2. Th QDA ws don in duplit during two othr sssions, undr th sm onditions s usd in th sorting tsk (bov) Dt nlysis Sttistil nlysis ws rrid out using PASW Sttistis 18 softwr (SPSS In. Chigo, IL, USA). To stimt th influn of th ftors ph, suros nd protin onntrtion on th gl instrumntl txtur, n nlysis of vrin (ANOVA) of th dt ws prformd. Mns omprison ws rrid out with th lst signifint diffrns (LSD) lultd with th Fishr tst t lvl of 95%. Sorting tsk dt wr nlysd by pplying multidimnsionl sling mthod. Anlysis of vrin (ANOVA) ws rrid out to ssss snsory ttributs signifintly diffrnt mong smpls. Th vribility of h dsriptor ws studid using modl whr th ssssor ws onsidrd rndom ftor nd smpl nd rplition fixd ftors. Multipl mns omprisons wr rrid out by

10 Studnt Nwmn-Kuls (SNK) tst t P < Prinipl Componnt Anlysis (PCA) ws ondutd to xmin th rltionship mong snsory ttributs nd smpls, orrltion mtrix ws usd nd th minimum ignvlu ws st t 1. Clustrs wr prformd by K Mns ommnd. Prson s Corrltion ws usd to xplor rltionships btwn snsory nd instrumntl dt. 3. Rsults nd disussion 3.1. Mirostrutur of th gls. Th onfol mirosopy imgs of gls n b sn in Fig. 1. Th lr rs orrspond to th fluorsn of rhodmin B, rvling th prsn of ntwork of WP. Th drk rs orrspond to wtr zons. Th gls prprd t ph 7 (Fig. 1d,,f) prsntd homognous distribution of fluorsn dots, whrs th gls prprd t ph 4 (Fig. 1,b,) xhibitd strutur of WP ggrgts with big pors. Ymul nd Lupno (2003) obsrvd tht whn gltion took pl t ph los to th isoltri point of WP ors prtiult strutur ws obtind du to th drs of th ltrostti rpulsion. Th isoltri ph of β-ltoglobulin (th min WP) is 4.6, xplining th diffrns in th strutur btwn ph 7 nd ph 4 gls (Fig. 1). Morovr, Boy t l. (2000) found tht, in gnrl, th siz of th protin lustrs nd th void sps within th gl mtrix tndd to drs s th ph hngd from id to bsi. At lklin ph protins r gnrlly mor unfoldd, xposing mor rtiv sits for rosslinking, nd thrfor nhns gl ntwork formtion (Boy t l., 2000). Th onntrtion of suros modifid th strutur minly of id gls (Fig. 1). Th gl strutur bm mor homognous nd pors bm smllr s suros ontnt

11 inrsd. Similr rsults wr obtind in othr systms, suh s millr sin gls (Shorsh, Jons, & Norton, 2002) nd WPC gls with hony (Ymul & Lupno, 2003). This ould b xplind by tking into ount tht suros inrsd th ttrtion btwn WP moluls through hydrophobi intrtions (Bir & MClmnts, 2001; Kim, Dkr, & MClmnts, 2003; Kulmyrzv t l., 2000; Kulmyrzv, Cnllir, & MClmnts, 2000b). Nutrl gls lrdy prsntd n homognous strutur bfor th ddition of suros; thus, only slight hng in th gl mirostrutur ws obsrvd (Fig. 1) Txturl proprtis. Fig. 2 shows th txtur proprtis of WPC gls with diffrnt ontnt of suros nd WP prprd t ph 4 nd ph 7. As WP ontnt inrsd, n inrs in th hrdnss, Young modulus, lstiity nd ohsivnss of th gls ws obsrvd. Th inrs in ths prmtrs n b xplind by n inrs in th lvl of ross-linking btwn th moluls s WP ontnt inrss. Aid gls wr mor dhsiv nd lss ohsiv thn ph 7 gls, spilly t high suros ontnt nd t 10% (w/w) WP. Cohsivnss is funtion of th nrgy tht holds moluls togthr in th gl strutur. Sulphydryl-disulphid intrhng rtions r fvourd in nutrl gls, whih ould xplin thir highr ohsivnss. Suros slightly drsd th lstiity of gls t ny onditions ssyd (Fig. 2) but inrsd hrdnss, Young s modulus, ohsivnss nd dhsivnss of WPC gls. On th othr hnd, suros inrsd th dhsivnss of gls du to its bility to form hydrogn bonds, spilly in id gls. Nutrl gls wr mor ohsiv nd, thus, would hv lss 212 bility to dhr to th mtl of th prob. 213

12 Wtr holding pity Fig. 3 dpits th WHC of WPC gls s funtion of suros nd WP ontnt Signifint diffrns (P <0.001, Tbl 3) wr obsrvd in WHC t diffrnt suros ontnt t both ph vlus studid, rhing similr vlus t high suros onntrtion. On th othr hnd, protin ontnt did not modify signifintly th WHC of gls (P > 0.05; Tbl 3). Aid gls xhibitd n ggrgtd strutur with big pors (Fig. 1,b,); thus, th flux of wtr in id gls would b sir thn in nutrl gls, xplining thir lowr WHC. Similr rsults wr obtind by Vrhul nd Rofs (1998) with WP gls prprd with diffrnt ontnts of NCl. On th othr hnd, t ph 7, gls xhibit high WHC; thus, it is xptd tht th nrgy dissiption in th visous modulus du to th flow of liquid through mtrix will b low, nd gls would bhv primrily lsti. Hydrogn bonds btwn smll moluls signifintly inrs th visosity of liquid, nd th bonds r wk nough to b tmporrily xtndd, xhngd or brokn (Pomrnz, 1978). Suros hs th possibility to form hydrogn bonds with wtr moluls nd, thus, inrsd th visosity of th solution trppd within th gls pors. As suros ontnt inrss th visosity of th solution lso inrsd nd th liquid flux through th mtrix drsd, xplining th high wtr-holding pity of gls ontining suros (Fig. 3) Snsory nlysis Smpl sltion Smpls for snsory nlysis wr sltd bsd on th rsults of th instrumntl nlysis, kping only smpls with suros onntrtion of 10, 20 nd 40% (w/w).

13 Smpls without suros (0%, w/w) wr not onsidrd bus thy wr not signifintly diffrnt (P > 0.05) from thos with 10% (w/w) of suros in mny of th onditions ssyd, nd lso du to th potntil off-flvour of th WPC gls without suros tht n driv from th vribl mounts of rsidul ltos nd 3 7% (w/w) lipid mtrils tht r susptibl to hmil rtions (Morr & H, 1991). All smpls with 30% (w/w) suros nd 15% (w/w) protin wr lso disrdd bus thy wr not signifintly diffrnt (P > 0.05) from th nxt orrsponding onntrtions in lmost ll onditions ssyd Sorting tsk Sorting tsk rsults r prsntd in Fig. 4. Aording to this nlysis, two mjor groups of smpls wr formd, bsd minly on protin onntrtion. On th on hnd, smpls ontining 10% (w/w) protin (smpls 2, 3, 5, 17, 18 nd 20) ould b hrtrisd by th ttributs rmy, wt surf, smooth, bright, humidity, soft nd ohsiv. On th othr sid, smpls ontining 20% (w/w) protin (smpls 12, 13, 15, 27, 28 nd 30 wr dsribd s dry, frturbl, hrd nd rough. Within h group rtin smpls wr too los or vn suprimposd, showing tht no diffrns wr found (Fig. 4). This ws th s for smpls 2, 3 nd 5 (ph 4, 10% protin, 10, 20 nd 40% suros rsptivly) nd smpl 17 nd 18 (ph 7, 10% protin, 10 nd 20% suros rsptivly) in th first group nd smpls 13 nd 15 (ph 4, 20% protin, 20 nd 40% suros rsptivly) nd smpls 27 nd 28 (ph 7, 20% protin, 10 nd 20% suros, rsptivly) in th sond group. Thrfor, to nlys by QDA only thos smpls privd s diffrnt, smpls 3, 18, 13 nd 28, whih lso hd n intrmdit sugr 262 onntrtion (20%, w/w), wr disrdd. 263

14 Txtur profil nd swtnss quntifition An ANOVA of th mixd modl for ll snsory quntifid ttribut sors ws prformd to vlut snsory pnl prformn nd diffrns mong smpls (Tbl 3) It ws found tht th sours of vrition wr smpls (P <0.001), nd ssssors only for hrdnss nd moistnss (P <0.05), inditing tht th pnl hd good prformn for quntifying ttributs, rpliting rsponss nd disriminting mong smpls. Morovr, th fft of protin ontnt, ph nd suros ws studid on both snsory prption nd instrumntl msurmnts; this is lso shown in Tbl 3. ph nd protin wr th min ftors tht fftd snsory nd instrumntl txtur msurmnts (P <0.001), xpt for WHC, for whih it ws suros ontnt tht ws th ftor tht most inflund WHC of gls. Although suros hd strong fft (P <0.001) on instrumntl hrdnss, it ws not rfltd on snsory hrdnss; probbly, th msurd diffrns wr within th diffrntil thrshold so thy wr not privd by th ssssors. Mn vlus of ll vlutd ttributs for h smpl r prsntd in Tbl 4. In trms of swtnss no signifint diffrns wr privd btwn two oupls of smpls: smpls 15 nd 20 (both 40% suros; ph % protin nd ph 7+ 10% protin, rsptivly) nd 17 with 28 (both ph 7; 10% protin +10% suros nd 20% protin + 20% suros, rsptivly). In ll ss, s suros onntrtion inrsd, swtnss prption lso inrsd. Howvr, t sm suros onntrtion, swtnss prption ws smllr s protin onntrtion inrsd nd this rdution ws mor importnt t ph 7. This is probbly rltd to th ft tht gls with highr mount of protin prprd t nutrl ph hd 287 hrdr txtur (Fig. 2b), whih might drs mss trnsfr, rduing th suros ss to

15 tst rptors. Morovr, s sid bfor, suros fvours intrtions btwn protin moluls rduing th ontt with th surrounding solution. Litrtur shows tht in gls drivd from rrgnn, glln, ptin nd/or gltin (Byrri, Durn, & Costll, 2003; Bolnd, Dlhunty, & vn Ruth, 2006; Costll, Pyrolon, & Durn, 2000; Guihrd, Issnhou, Dsourvirs, & Etivnt, 1999; Lundgrn t l., 1986) prption of swtnss drsd with inrsing hrdnss. Morovr, s gnrl rul, it is known tht th highr th hydroolloid onntrtion, th lowr th privd swtnss intnsity (Byrri t l. 2007). To bttr intrprt th dt obtind from th txturl profil, PCA ws rrid out with th mn vlus obtind for h smpl; th biplot of Prinipl Componnt 1 (PC1) vrsus Prinipl Componnt 2 (PC2) is prsntd in Fig. 5. This nlysis xplind 94% of th vrin mong smpls with th first two omponnts. Th min ttributs omposing PC1 wr hrdnss, roughnss nd ohsivnss, togthr with moistnss nd rminss, whih wr opposit to th formntiond. PC2 ws positivly dfind by dhsivnss of mss, dhsivnss to tth nd thiknss. It n b sn tht smpls 27 nd 30 (both ph 7 nd 20 %, w/w, protin, 10 nd 40%, w/w, suros, rsptivly) wr groupd nd dsribd mostly by th ttributs hrdnss, roughnss, lstiity nd ohsivnss (Fig. 5); smpls 17 nd 20 (both ph 7 nd 10% protin, 10 nd 40% suros, rsptivly) wr minly hrtrisd ording to moistnss; smpls 12 nd 15 (both ph 4 nd 20% protin; 10 nd 40% suros, rsptivly) ording to dhsivnss of mss nd to tth togthr with thiknss nd finlly smpls 2 nd 5 (both ph 4 nd 10% protin; 10 nd 40% suros, rsptivly) wr th rmist. This onfirmd rsults showd in Tbl 3, tht suros ws th lst importnt 311 ftor influning privd txtur in omprison to ph nd protin onntrtion. 312

16 Instrumntl nd snsory orrltion To ompr instrumntl nd snsory informtion, Prson s Corrltion ws don; th rsults r shown in Tbl 5. A high positiv orrltion ws found btwn th instrumntl nd snsory ttributs hrdnss (P <0.01), ohsivnss (P <0.01) nd lstiity (P <0.001), showing tht th msurd proprty ws th sm by both thniqus. Instrumntl hrdnss lso orrltd with th snsory ttributs roughnss (P <0.01), ohsivnss (P <0.01) nd in lowr proportion with lstiity (P <0.05). Probbly, surf ttil informtion suh s roughnss (s Tbl 2 for dfinition) ould lso ontribut to hrdnss prption. Evn if snsory dhsivnss (dhsivnss of mss nd dhsivnss to tth) did not signifintly orrlt with th instrumntl msurmnt of dhsivnss, th instrumntl msurmnt of dhsivnss orrltd with privd rminss nd swtnss (P <0.05). It must b tkn into ount tht suros inrsd th dhsivnss nd th swtnss of smpls; thus, th orrltion btwn th instrumntl msurmnt of dhsivnss nd th privd swtnss ould b du to th ft tht ll ths ttributs inrsd with suros ontnt. Crminss n b ssoitd with th low lstiity of th smpls, whih drsd whn suros ontnt inrsd. 4. Conlusions Th prsn of suros modifid th strutur of WPC gls minly t id ph, mking th gl strutur mor homognous nd with smllr pors. Suros lso inrsd th solid bhviour of gls, thir WHC, hrdnss nd dhsivnss. An inrs in th suros ontnt highr thn 10 % (w/w) ws ndd to priv hngs in swtnss in WPC gls t nutrl or idi ph. Swtnss prption drsd s protin onntrtion inrss. Also, swtnss of gls prprd t ph 4 ws highr thn swtnss of gls

17 prprd t nutrl ph, inditing tht txtur is mor importnt thn th id tst usd by ph in th prption of th swtnss of ths gls. Th instrumntl nd snsory ttributs hrdnss, ohsivnss nd lstiity showd good orrltion, inditing tht th msurd proprty ws th sm by both thniqus. This informtion ould b usful for th food industry sin snsory vlution by trind pnl is ost nd tim dmnding. Aknowldgmnts Th uthors would lik to thnk th finnil support from CONICET (PIP 1643) nd th snsory pnl for thir ooprtion.

18 1 348 Rfrns Bir, S., & MClmnts, D. (2001). Impt of prfrntil intrtions on thrml stbility nd gltion of BSA in quous suros solutions. Journl of Agriulturl nd Food Chmistry, 49, Byrri, S., Durn, L., & Costll, E. (2003). Comprssion rsistn, swtnrs diffusion nd swtnss of hydroolloid gls. Intrntionl Diry Journl, 13, Byrri, S., Rivs, I., Izquirdo, L., & Costll, E. (2007). Influn of txtur on th tmporl prption of swtnss of glld systms. Food Rsrh Intrntionl, 40, Bolnd, A. B., Dlhunty, C. M., & vn Ruth, S. M. (2006). Influn of th txtur of gltin gls nd ptin gls on strwbrry flvour rls nd prption. Food Chmistry, 96, Boy, J. I., Klb, M., Alli, I., & M, C. Y. (2000). Mirostruturl proprtis of ht-st why protin gls: Efft of ph. Lbnsmittl-Wissnshft und Thnologi, 33, Cssini, D. M., Ymul, D. K., Conforti, P. A., Pérz, V. A., & Lupno, C. E. (2011). Strutur nd funtionlity of why protin onntrt-bsd produts with diffrnt wtr ontnts. Food nd Biopross Thnology. Artil in prss (07/08/2012). DOI: /s x

19 Clrk, A., Judg, F., Rihrds, J., Stubbs, J., & Suggt, A. (1981). Titl Intrntionl Journl of Pptid Protin Rsrh, 17, Costll, E., Pyrolon, M., & Durn, L. (2000). Not. Influn of txtur nd typ of hydroolloid in prption of bsi tsts in rrgnn nd glln gls. Food Sin nd Thnology Intrntionl, 6, DMrs, L. L., & Ziglr, G. R. (2001). Txtur nd strutur of gltin/ptin-bsd gummy onftions. Food Hydroolloids, 15, Dirkx, S., & Huyghbrt, A. (2002).Effts of suros nd sorbitol on th gl formtion of why protin isolt. Food Hydroolloids, 16, Guihrd, E., Issnhou, S., Dsourvirs, A., & Etivnt, P. (1999). Ptin onntrtion, molulr wight nd dgr of strifition: influn on voltil omposition nd snsory hrtristis of strwbrry jm. Journl of Food Sin, 55, Gwrtny, E., Lrik, D., & Fogding, E. A. (2004). Snsory txtur nd mhnil proprtis of strndd nd prtiult why protin mulsion gls. Journl of Food Sin, 69, Holm, K., Wndin, K., & Hrmnsson, A. M. (2009). Swtnss nd txtur prption in mixd ptin gls with 30% sugr nd dsignd rhology. Lbnsmittl-Wissnshft und Thnologi, 42,

20 Huffmn, L. M. (1996). Prossing why protin for us s food ingrdint. Food Thnology, Johnson, B. R. (2000). Why protin onntrts in low-ft pplitions. Applitions Monogrph. OK, USA: FS&T Consulting. Kim, H., Dkr, E., & MClmnts, D. (2003). Influn of suros on droplt floultion in hxdn oil wtr mulsion stbilizd by β-ltoglobulin. Journl of Agriulturl nd Food Chmistry, 51, Kulmyrzv, A., Brynt, C., & MClmnts, D. (2000). Influn of suros on th thrml dnturtion, gltion nd mulsion stbiliztion of why protins. Journl of Agriulturl nd Food Chmistry, 48, Kulmyrzv, A; Cnllir, C., & MClmnts, D. (2000b). Influn of suros on old gltion of ht-dnturd why protin isolt. Journl of th Sin nd Food Agriultur, 80, Llivr,?? Chollt,?? Abdi,?? & Vlntin??. (2008). Wht is th vlidity of th sorting tsk for dsribing brs? A study using trind nd untrind ssssors. Food Qulity nd Prfrn, 19,

21 Lthuut, L., Brossrd, C., Roussu, F., Boussu, B., & Gnot, C. (2003). Swtnss txtur intrtions in modl diry dssrts: fft of suros onntrtion nd th rrgnn typ. Intrntionl Diry Journl, 13, Lundgrn, B., Pngborn, R. M., Dgt, N., Yoshid, M., Ling, D. G., & MBrid, R. L. (1986). An intrlbortory study of firmnss, rom nd tst of ptin gls. Lbnsmittl-Wissnshft und Thnologi, 19, Lupno, C. E., Dumy, E., & Chftl, J. C. (1992). Glling proprtis of why protin isolt: influn of lium rmovl by dilysis or difiltrtion t id or nutrl ph. Intrntionl Journl of Food Sin nd Thnology, 27, Moritk, H., & Ntio, S. (2002). Agr nd gltin gl flvor rls. Journl of Txtur Studis, 33, Morr, C., & H, E. (1991). Off-flvours of why protin onntrts: A litrtur rviw. Intrntionl Diry Journl, 1, Ohms, R. L., Mrshll, R. T., & Hymnn, H. (1998). Snsory nd physil proprtis of i rms ontining milk ft or ft rplrs. Journl of Diry Sin, 81, Pomrnz, Y. (1978). Composition nd funtionlity of wht-flour omponnts. In Y. Pomrnz (Ed.), Wht. Chmistry nd thnology (pp ). St. Pul, MN, USA: Am. Asso. Crl Chm., In.

22 Shorsh, C., Jons, M. G., & Norton, I. T. (2002). Millr sin gltion t high suros ontnt. Journl of Diry Sin, 85, Shimd, K., & Chftl, J. C. (1988). Txtur hrtristis, protin solubility, nd sulphydryl group/disulfid bond ontnts of ht-indud gls of why protin isolt. Journl of Agriulturl nd Food Chmistry, 36, Stding, M., Lngton, M., & Hrmnsson, A. (1993). Mirostrutr nd rhologil bhvior of β-ltoglobulin gl struturs. Food Hydroolloids, 7, Ston, H., & Sidl, J. L. (1993). Snsory vlution prtis. (2nd dn.). Sn Digo, CA, USA: Elsvir Admi Prss. Szzsnik, A. S., & Khn, E. L., (1971). Consumr wrnss of nd ttituds to food txtur. Journl of Txtur Studis, 2, Tng, Q., MCrthy, O., & Munro, P. (1995). Osilltory rhologil study of th gltion mhnism of why protin onntrt solutions: fft of physiohmil vribls on gl formtion. Journl of Diry Rsrh, 60, Vrhul, M., & Rofs, S. (1998). Strutur of why protin gls, studid by prmbility, 468 snning ltron mirosopy nd rhology. Food Hydroolloids, 12,

23 Ymul, D. K., & Lupno, C. E. (2003). Proprtis of gls from why protin onntrt nd hony t diffrnt phs. Food Rsrh Intrntionl, 36, Ymul, D. K., & Lupno, C. E. (2005). Why protin onntrt gls with hony nd wht flour. Food Rsrh Intrntionl, 38, Ymul, D. K., & Lupno, C. E. (2009). Visolsti proprtis of why protin onntrt gls with hony nd wht flour t diffrnt ph. Journl of Txtur Studis, 40,

24 2 479

25 Tbl 1 Composition of id nd nutrl WPC gls s funtion of protin nd suros ontnt. ph Smpls Protin Suros (%, w/w) (%, w/w) 1, 2, 3, 4, , 10, 20, 30, , 7, 8, 9, , 10, 20, 30, , 12, 13, 14, , 10, 20, 30, , 17, 18, 19, , 10, 20, 30, , 22, 23, 24, , 10, 20, 30, , 27, 28, 29, , 10, 20, 30, 40 7 Vlus r rsptiv to th smpl numbr.

26 Tbl 2 Snsory ttribut dfinitions, smpl mnipultion produrs nd rfrns hosn. Attribut Dfinition Rfrns Swtnss Hrdnss Roughnss Moistnss Elstiity-springinss Cohsivnss Firmnss Adhsivnss of mss Adhsivnss to tth Crminss Tst ssoitd to suros solution. For rquird to ut ompltly through th smpl whn pld btwn inisiv tth Dgr of brsion givn by th surf of th produt privd on th lips nd tongu. Prption of wtr ontnt rlsd by th surf of th produt. It ws msurd with th smpl in th mouth, ovr th tongu nd lips Dgr or rt t whih th smpl rturns to its originl siz-shp ftr prtil omprssion btwn th tongu nd plt. Dgr to whih smpl holds togthr s mss. Rsistn of th smpl to movmnt or flow. It ws msurd s th for rquird to mov th smpl long th plt using th tongu. Dgr to whih mss stiks to th plt or tth (not stiky vry stiky). Amount of produt whih stiks to th tth ftr mstition. Soft txtur, vlvty, smooth fling whih dispprs whn th mouth is rinsd Suros solutions t 5 nd 15% (-) xtrm: rm hs Middl sl: olivs, hotdogs (+) xtrm: hrd ndy (-) xtrm: gltin (+) xtrm: rl br. (+) xtrm: mrshmllow (+) hwing gum

27 Tbl 3 Anlysis of vrin rsults showing snsory pnl prformn, diffrns mong smpls nd fft of protin, ph nd suros on vlutd snsory nd instrumntl ttributs. Attribut F-vlus Smpl Assssor Rplition ph Protin Suros Snsory Swtnss 1072 *** *** 1264 *** 9577 *** Hrdnss 794 *** 2.2 * *** 5377 *** 0.4 ns Roughnss 1137 *** *** 5085 *** 232 *** Moistnss 2031 *** 2.5 * *** *** 10.3 ** Elstiity 502 *** *** 1203 *** 4.8 * Cohsivnss 1389 *** *** 1897 *** 8.0 * Firmnss 302 *** *** 2113 *** 23.9 *** Adhsivnss mss 890 *** *** 162 ** 356 *** Adhsivnss tth 354 *** *** 2135 *** 185 *** Crminss 790 *** *** 2572 *** 41.7 *** Instrumntl Hrdnss 65 *** 187 *** 122 *** Elstiity 143 *** 22 *** 2.5 ns Young s modulus (E) 1228 *** 414 *** 304 *** Adhsivnss 46 *** 134 *** 46 *** Cohsivnss 138 *** 35 *** 8.3 * WHC 3.5 ns 1 ns 57.4 *** Signifin vlus r: * P < 0.05, ** P < 0.01, *** P < 0.001; ns, not signifint.

28 Tbl 4 Mn vlus for snsory ttributs. Attribut Smpl numbr Swtnss 48.2± ± ± 4.0 d 114.6± 10.3 f 26.9± 2.2 g 117.5± 9.7 f 6.8± 0.4 i 59.6± 4.4 j Hrdnss 17.1± ± ± 5.0 b 66.9± ± 0.3 d 28.9± ± 15.8 f 115.9± 12.6 f Roughnss 17.8± ± 2.9 b 95.4± ± 11.9 d 21.9± 3.5 b 30.5± ± 8.3 f 144.4± 10.3 g Moistnss 114.8± ± 6.3 b 38.5± ± ± 4.4 d 109.7± ± 0.7 f 24.1± 2.4 g Elstiity 16.7± ± 3.0 b 50.0± ± 4.0 d 64.3± ± ± 10.6 f 86.9± 7.8 g Cohsivnss 9.4± ± ± 6.0 b 37.4± ± 6.3 d 57.1± 5.6 b 123.7± ± 10.9 f Firmnss 37.8 ± ± 8.0 b 118.8± ± 5.0 d 7.5± ± ± 5.1 f 78.6± 8.6 g Adhsivnss of mss 64.8 ± ± 6.0 b 116.1± ± 12.0 d 19.9± ± 6.8 f 7.1± 0.3 g 21.8± 2.6 Adhsivnss to tth 61.9± ± ± 8.4 b 120.4± ± 0.3 d 31.2± ± 6.9 f 92.3± 9.4 g Crminss 140.6± ± 12.1 b 74.1± ± ± 3.7 d 83.4± ± 0.3 f 19.6± 2.6 g S Tbl 1 for smpl omposition. Diffrnt suprsript lttrs within h row indit signifint diffrns mong smpls ording to Studnt Nwmn-Kuls (SNK).

29 Tbl 5 Prson s orrltion btwn instrumntl nd snsory prmtrs Instrumntl Snsory prmtr prmtr Hrdnss Roughnss Moistnss Elstiity Adhsivnss mss Adhsivnss tth Cohsivnss Firmnss Crminss Swtnss Elstiity *** * ** ** Adhsivnss * * * * Cohsivnss ** ** ** WHC Hrdnss ** ** * * ** * Young s ** ** ** modulus Swtnss Signifin vlus r: * P < 0.05, ** P < 0.01, *** P <

30 1 1 Figur ptions 2 3 Fig. 1. Mirostrutur of WPC gls with diffrnt mounts of suros obsrvd by onfol lsr snning mirosopy. Suros ontnt: pnls nd d, 0% (w/w); pnls b nd, 20% (w/w); pnls nd f, 40% (w/w). ph of gls: pnls, b, nd, ph 4; pnls d,, nd f, ph 7. Protin ontnt of ll gls ws 10%, w/w. Fig. 2. Hrdnss, Young s modulus, springinss, dhsivnss nd ohsivnss of WPC gls s funtion of suros ontnt. Protin ontnt of gls:, 10% (w/w);, 15% (w/w);, 20% (w/w). Pnls,,, g, nd i r ph 4; pnls b, d, f, h, nd j r ph 7; brs show stndrd dvition. Vlus in th sm grph with lttr in ommon r not signifintly diffrnt (P > 0.05). Fig. 3. Wtr holding pity of WPC gls s funtion of suros nd WP ontnt:, 10% (w/w/) WP; 15% (w/w/) WP;, 20% (w/w/) WP;. Pnl, ph 4; pnl b, ph 7. S Tbl 1 for smpl omposition; brs show stndrd dvition. Fig. 4. Sorting tsk rprsnttion of th vlutd smpls; s Tbl 1 for smpl omposition. Fig. 5. Prinipl omponnt nlysis of th snsory txtur profil; s Tbl 1 for smpl omposition

31 Figur 1 b d f 10 µm

32 Figur 2 Hrdnss (N) Adhsivnss (N/s) Elstiity Young modulus (kp) Cohsivnss ,36 0,30 0,24 0,18 0,12 0,06 0,5 0,4 0,3 0,2 0,1 0,0 1,2 1,1 1,0 0,9 0,8 0,7 0,6 () (b) (b) () b () d f (g) i (i) b f d b f f b b b f g g b d g d b g b d i f d g f j f k h k b d b d d d d f Suros (%, w/w) Suros (%, w/w) (d) (h) d (j) d f b d d d g d f d f b (j) g b f (f) b f (h) (d) b b f

33 Figur 3 WHC (%) WHC (%) () (b) 10% w/w WP 15% w/w WP 20% w/w WP 10% w/w WP 15% w/w WP 20% w/w WP Suros (%, w/w)

34 Figur Dimnsion thrshd_mss thrshd_mss roughnss 30 rough dry 12 hrd frturbl dhsiv_tth dhsiv ompt_m ompt_mss springy visosit thiknss rmy 2 wt_surf smooth 3 5 bright 17 humidity soft ohsivnss Dimnsion 1

35 Figur 5 PC 2 (31.6%) Crminss 2 Moistnss Adhsivnss mss Adhsivnss Adhsivnss tth tt Thiknss Elstiity Roughnss Hrdnss PC 1 (62.4%) 27 Cohsivnss 30