RHEOLOGICAL CHARACTERIZATION OF COFFEE- FLAVORED YOGURT WITH DIFFERENT TYPES OF THICKENER*

ISSN 13-4235 ISSN 2179-4448 o lie Alim. Nutr., Araraquara v. 22,. 4, p. 521-529, out./dez. 211 RHEOLOGICAL CHARACTERIZATION OF COFFEE- FLAVORED YOGURT WITH DIFFERENT TYPES OF THICKENER* Thiago Rocha dos Satos MATHIAS** Itamar Cabral de CARVALHO JUNIOR*** Carlos Waderlei Piler de CARVALHO**** Eliaa Flávia Camporese SÉRVULO***** ABSTRACT: Yogurt is a fuctioal food that has great demad due to the cosumer s search for a healthier diet. I order to expad the cosumer market of this product, may flavors are available, satisfyig the most varied prefereces. Besides the taste attribute, cosistecy ad viscosity of yogurt are some of the mai factors ivolved i product quality ad acceptace. Therefore, this work is a study of the ifluece of cocetratio of thickeer i coffee-flavored yogurt. The thickeer aget used was gelati. The rheological behavior (flow ad viscosity curves) of yogurts with ad without additio of gelati was compared with commercial yogurt, which cotais aother type of thickeer (locust bea gum) i its formulatio. The flow ad viscosity curves were obtaied from rotatioal rheometer Thermo Haake Mars, with a rage of shear rate from.2 to 1 s -1 (risig curve) ad 1 to.2 s -1 (descedet curve) at a total time of 2 miutes. Hysteresis was determied as the area betwee the curves ad adjusted to the models of Bigham, Casso, Herschel-Bulkley ad Ostwald-de-Waele. Were also carried out tests of thixotropy, by measurig the viscosity as a fuctio of time at a costat rate of 1 s -1 for 1 miutes. These curves were adjusted by the Weltma model. All samples showed pseudoplastic ad thixotropic behavior. The Herschel-Bulkley model was the best fit to the three samples tested. The Weltma s model well described the thixotropy tests, except for the sample of commercial yogurt. The use of gelati as a thickeer showed protective character, reducig the structural break of the gel. KEYWORDS: Rheological models; pseudoplastic behavior; gel stability; viscosity. INTRODUCTION The search for a healthier diet is becomig icreasigly prevalet throughout the world. People cocered about their health ad well-beig have esured a growig demad for healthy products. I this cotext, emerge the called fuctioal foods, which besides their basic utritioal fuctios, provide may beefits to huma health. 3, 32 There are a wide variety of products with this appeal, ad the dairy idustry has a importat role i this market. 13 Yogurt ca be oted betwee fuctioal foods. It is a product obtaied from the fermetatio of milk by the symbiotic actio of traditioal lactic microorgaisms, Streptococcus thermophilus ad Lactobacillus bulgaricus. 4 Rich i protei, folic acid, vitamis A, B ad mierals, its regular cosumptio brigs may health beefits, such as gastroitestial regulatio, stimulatio of the immue system, etc. 6 Coffee is a product cosumed daily i the world by all social classes. 24 Brazil is the largest producer ad secod cosumer market i the world. 1 The coffee has about 1 to 2.5% caffeie ad other substaces i greater quatity. The coffee beas (gree coffee) feature a large variety of mierals, amio acids, lipids ad sugars. Additioally, the coffee also has a vitami B, iaci (vitami B3 or vitami PP), ad chlorogeic acids, which, after roastig, form 2, 5, 11, 23 several compouds with pharmacological effects. Some effects of coffee o health are: reductio of cholesterol, aid agaist heart disease, atidepressat effects, reduced risk of Parkiso s disease, protectio agaist type 2 diabetes, atioxidat, aidig i weight loss procedures ad prevetio of some types of cacer (colo 7, 2, 21, 26, 3 ad rectum). The cosumptio of yogurt has experieced sigificat icreases ad there are various types to achieve the broad cosumer market. These products may vary accordig to the igrediets, compositio, flavor, cosistecy, texture, caloric value, developmet process ad ature of the process of post-hatchig. 29 The fial product quality has great importace i its acceptace, ad is iflueced maily by its cosistecy ad viscosity. * Fiacial support of Natioal Coucil for Scietific ad Techological Developmet CNPq Brazil. (Process Number 131378/21-4). ** Federal Istitute of Educatio, Sciece ad Techology of Rio de Jaeiro 227-21 Rio de Jaeiro RJ Brazil. E-mail: thiago.mathias@ifrj.edu.br. *** Cosultat i Food ad Beverage Techology 21941-99 Rio de Jaeiro RJ Brazil. **** Brazilia Agricultural Research Compay EMBRAPA 232-47 Rio de Jaeiro RJ Brazil. ***** School of Chemistry Federal Uiversity of Rio de Jaeiro 21941-99 Rio de Jaeiro RJ - Brazil. 521

The texture of the product ad propesity to syeresis (serum separatio) are the mai characteristics that will defie the quality of yogurt. 19 Geerally, to icrease the viscosity, the practice used i idustries is to icrease the solids cotet by addig milk or whey powder. 37 However, thickeers ca be added for this purpose, leavig a firmer texture, reducig syeresis ad icreasig the acceptability of the yogurt. Various polymeric materials ca be used as thickeers ad its origis ca be vegetable or microbial. Amog the polysaccharides, are promiet: starch, pecti, carrageea, algiates, xatha gum, gella gum ad arabic gum. Betwee the proteiaceous materials, are the caseiate ad gelati. 39 Accordig Walstra et al., 4 ad Tamime & Robiso, 37 three of the most commoly used thickeers are starch, pecti ad gelati. May factors ca affect the rheology of yogurt, as solids, protei ad fat cotet, temperatures of heat treatmet 8, 28 of milk ad fermetatio, homogeizatio pressure, etc. So the aim of rheological studies is to verify the structural stability of the food ahead of possible processes, allowig the correct sizig of pumps, pipig, heat exchagers, stirrig ad bottlig operatios, etc., without affectig the quality of the fial product. 27 Besides these, other applicatios of rheological studies are the quality cotrol, sesory aalysis ad shelf life testig. 1 Rheological studies usually ivolve relatioships betwee shear rate ad shear stress. Whe the relatioship is liear, the fluid is referred ewtoia ad its viscosity is costat, idepedet of the rate ad shear stress applied. However, i may cases, this relatioship is oliear ad the fluid is classified as o-newtoia. These fluids ca be pseudoplastic fluids, which have lower viscosity with icreasig shear rate applied. 31 Besides the depedece of the rate, the pseudoplastic fluids ca be thixotropic, also depedet o the time of shearig. I this case, eve for costat shear rates, viscosity is reduced to a fuctio of time. Flow curves of thixotropic fluids preset distictio betwee the curves of icreasig rate ad decreasig rate, ad this pheomeo is kow as hysteresis. Models such as the Ostwald-de-Waele, Hershel- Bulkley ad Casso, while ot takig ito cosideratio the depedece over time, have bee well applied to describe 25, 27, 39 the rheological behavior of these fluids. Thus, this study aimed to assess the rheological behavior of coffee- flavored yogurt as a fuctio of differet cocetratios of thickeer (gelati) ad its compariso with commercial yogurt that use other thickeers i its formulatio. It was verified the ifluece of thickeers o the viscosity as a fuctio of time ad shear rate, ad adjusted the models of Bigham, Casso, Herschel-Bulkley ad Ostwald-de-Waele to the flow curves ad the Weltma s model to thixotropy test. MATERIALS AND METHODS The yogurt was developed ad produced at Laboratory of Idustrial Microbiology, at the Departmet of Biochemical Egieerig, School of Chemistry / Federal Uiversity of Rio de Jaeiro. The followig materials were used to prepare the samples of the yogurt: 18, 37 itegral UHT milk (Elegê, BRF Brasil Foods S.A, Chapecó, SC, Brazil) (1L), powered itegral milk (Niho/Nestlé, São Paulo, SP, Brazil) (6g L -1 ), refied sugar (Uião, Copersucar, São Paulo, SP, Brazil) (1g L -1 ) ad commercial lyophilized starter cultures (1g L -1 ) of trademark Rich (Chr Hase Valihos, SP) cotaiig a supercocetrated of the two strais of lactic acid bacteria Lactobacillus bulgaricus ad Streptococcus thermophilus. It was used istat coffee as flavorig aget (Nescafé/Nestlé, São Paulo, SP, Brazil) (3g L -1 ). The samples were prepared with two differet cocetratios of thickeer (uflavored gelati colorless - Dr. Oetker ), ad 6g L -1, coded as follows: CYNT (coffee-flavoured yogurt without thickeer) ad CYT (coffee-flavored yogurt with thickeer) respectively. The yogurt maufacture was performed as idicated by Chada et al., 6 Walstra et al., 4 Tamime, 36 ad Rasic & Kurma: 29 UHT milk was heated to about 43 C for additio of igrediets (milk powder, istat coffee, gelati, sugar) ad the mixture was homogeized. The, it was ioculated ad icubated at 43 C for fermetatio. Durig the fermetatios, at itervals of 3 miutes, the moitorig of the ph was made by direct measuremet i a digital brad PHTEK (model PHS-3B). Whe the ph value reached 4.6, the process was iterrupted, ad soo after, the yogurt was cooled to 4 C, ad stored at this temperature. The commercial yogurt was purchased from the local market (Rio de Jaeiro, Brazil) ad coded as follows, with their thickeer: CY (locust bea gum). The yogurt samples were submitted to aalytical determiatios of ph values (by direct measuremet o phmeter) ad water cotet (by dryig at 15ºC). 17 Rheometry aalysis was performed i triplicate at Thermo Haake MARS rotatioal rheometer (Karlsruhe, Germay), equipped with geometry plate / plate, with 35mm of diameter, available at Brazilia Agricultural Research Compay (EMBRAPA/Rio de Jaeiro, Brazil). The rheometer has a Haake Mars Cotroller Peltier type to temperature, whose value was adjusted to 8ºC for all 14, 33 aalyses. Before performig the aalysis, all samples of yogurt were also subjected to agitatio i mixer for 1 (oe) miute, uder rotatio speed of 15rpm ad the remaied 28, 33 at rest uder refrigeratio (1ºC) for 1 miutes. To obtai the flow ad viscosity curves, aalyzig the variatio of tesio ad viscosity as a fuctio of shear rate, respectively, the rate raged from.2 to 1s -1 (risig curve) ad betwee 1 ad.2s -1 (descedig curve) eablig the determiatio of the hysteresis as the area betwee the curves. The total aalysis time was 2 mi. ad collected 8 poits i total. Thixotropy tests were performed by applyig a costat shear rate of 1s -1 ad the determiatio of 522

viscosity as a fuctio of time of 1 mi., collectig 4 poits. For all the aalyses, it was used the software Haake RheoWi 3 to obtai the curves, adjustig the models ad calculatio of hysteresis. The results were fitted to the models of Bigham, Casso, Herschel-Bulkley ad Ostwald-de- Waele. 33 The model of Weltma, time-depedet, was also tested. 14 Statistical aalysis of results by ANOVA was carried out usig the software Microsoft Excel 23, to compare the differet models adjusted. Table 1 shows the rheological models adjusted. RESULTS AND DISCUSSION Idepedet of the cocetratio or type of thickeer used, all samples of yogurt showed behavior of o-newtoia ad pseudoplastic fluid, with viscosity decreasig, with icreasig shear rate applied. 31 Accordig to Hore 16 ad Lucey, 22 this ca occur due to physical destructio of weak bods betwee the molecules of the product ad due to decreased eergy of iteractio betwee them. Several reviewed studies cofirm the yogurt as a 12, 14, 28, 38, 4 pseudoplastic fluid. Figures 1 ad 2 shows the flow ad viscosity curves, respectively, for the differet samples of yogurt. The sample of coffee-flavored yogurt with gelati as a thickeer showed the highest viscosity values (average viscosity about 381.1mPas) over the etire rage of shear rates examied. The, the highest values were obtaied for the sample of coffee-flavored yogurt without gelati (average viscosity about 37.3mPas) ad fially the sample of commercial yogurt (average viscosity about 286.3mPas). Supavititpataa et al., 35 evaluatig the effect of cocetratio of gelati i cor milk yogurt, also observed that icreasig the cocetratio promoted the formatio of a more cosistet product. The additio of thickeers was also assessed by Teles & Flores, 38 who observed a icrease i the viscosity of yogurt about 4 times due to icreased cocetratio of gelati from 4 to 8 g L -1. The results for aalytical determiatios are expressed i Table 2. Accordig to Tamime, 36 low ph values ca promote syeresis of yogurt, due to excessive repulsio charges, chagig its rheological properties, as observed for the CY sample that showed lower ph ad viscosity values. The water cotet was similar to the three samples tested, ad i this case, it was of irrelevat ifluece o rheological behavior. As observed i Figures 1 ad 2, all samples showed thixotropic characteristics, due to differeces of tesio ad viscosity betwee risig ad descedig curve. This Table 1 Rheological models. Model Viscosity Shear stress Bigham = η p + γ η / = + η p γ Casso η = / γ ) + ( ( η p ),5 =,5 + K(γ ),5 1 Ostwald-de-Weale η = K γ = K γ Where: Hersch-Bulkley 1 η = γ + K γ t = time / = + K γ Weltma - = A B. log( t) η = vis cosity( Pa. s) Κ = cosistecy. idex( Pa. s ) = behavior. idex(dim esioless) = shear. tesio( Pa) 1 γ = shear. rate( s ) η = plasticvis cosity p = yield. stregth A = rheo logical. parameter. like. B = rheo logical. parameter. tobreakage.. rate 523

FIGURE 1 Flow curves of the yogurt samples. FIGURE 2 Viscosity curves of yogurt samples. pheomeo is a result of breakage of the gel ad ca be quatified as the area betwee the flow curves. The larger the area betwee the curves, the higher the thixotropic effect. 17 Values are give i Table 3. As show i Table 3, the sample of CYNT, without additio of thickeer, preseted higher thixotropic characteristic, represeted by the largest calculated area of hysteresis. The remaiig samples, CYT ad CY showed slightly lower hysteresis values, i this sequece. This may idicate the protective effect of thicker agets o the gel of yogurt, reducig structural damage durig processig. Tables 4 ad 5 shows the values of the regressio coefficiet r for models adjusted for the upward flow curves ad viscosity of yogurt samples, respectively. 524

It is observed (Table 4) that oe of the four models tested adequately described (see low values of r) the rheological behavior of the upward flow curves for the sample CYNT, which preseted a very differet profile from the others, as oted i Figure 1. Performig aalysis of variace (ANOVA) at 5% sigificace level, it was obtaied P<.5 for the models which fit the flow curves, idicatig sigificat differeces betwee them. As for the viscosity curves, P>.5, showig that all models were well adjusted, with o sigificat differece. I virtually all cases, the best results were for the Herschel-Bulkley model (r>,99), whose calculated parameters for each sample are show i Table 6. I cotrast, the Bigham model preseted the worst fit to the curves of flow ad viscosity (is well oted for upward curves), which cofirms the oliear relatioship betwee stress ad shear rate, corroboratig the classificatio 31, 34 of yogurt aalyzed as o-newtoia fluids. The Ostwald-de-Waele model, as well as the Herschel-Bulkley model, cosiders the oliear relatioship betwee stress ad shear rate. However, the first model does ot take ito accout the yield stress ( ). 39 Because of the similarity betwee the models, except for a liear coefficiet i the mathematical equatio, both had fits with r values>.99. However, the model of Ostwaldde Waele leads to a loss of a importat iformatio for the processig of yogurt ( ), which measures the miimum tesio ecessary for there to be flow. 34 It ca be see i Table 5 that all values of flow idex () are smaller tha 1, i agreemet with literature data, Table 2 Aalytical determiatios of yogurt samples. Sample ph Water cotet (%) CY 4,11 78 CYT 4,6 77,5 CYNT 4,7 78.5 Table 3 Hysteresis of yogurt samples. Sample Hysteresis (Pa/s) CYT 232.4 CYNT 355.5 CY 112 Table 4 r values for the models adjusted to the flow curves. Model r CYT CYNT CY Bigham.9341.716.9263 Ostwald Weale.9935.8959.9962 Casso.9698.86.9937 Herschel-Bulkley.9979.9256.9993 Table 5 r values for the models adjusted to the viscosity curves. Model r CYT CYNT CY Bigham.9777.9745.9898 Ostwald Weale.9988.9965.9997 Casso.9921.9873.9988 Herschel-Bulkley.9988.999.9997 Table 6 Parameters of Herschel-Bulkley model for the yogurt samples. Flow Curve (risig curve) K (Pa.s (Pa) ) CYT 17.83 19.81.1322 CYNT 163.8 168.8.14 CY 16.58 19.58.78 525

showig agai the classificatio of fluids aalyzed as o- 14, 38 Newtoia pseudoplastic. It should be oted that the results are cosistet for CYT ad CY samples, which were well fitted by the model (values of r ² =.9979 ad.9993, respectively). For these samples, the highest value of yield stress ( ), although quite close, was for the CYT sample, which showed higher viscosity values. Also cosistet with these results, the highest cosistecy idex (K) was obtaied for the CYT sample, compared with CY sample. The results for CYNT sample are ureliable because the value of r ² was the lowest, idicatig poor model fit to the curve (r ² =.9256). Several works have studied the rheological behavior of differet formulatios of yogurt, obtaiig as results for the yield stress ( ) values betwee 1.1 ad 1.1 Pa, depedig o the solids cotet, type of thickeer, type of starter culture (exopolysaccharide-producig or ot) ad presece of prebiotics. 14, 28, 33, 38 The results obtaied here idicate that the gelati acts as a thickeer with a strog impact by restrictig the flow of the fial product. The thixotropic characteristics are cofirmed by the aalysis of viscosity versus time at a costat shear rate. I accordace with the data preseted i the literature, all yogurt samples showed a reductio of viscosity versus time. 6, 9, 14, 25 The curves of viscosity over time are show i Figure 3, which represet thixotropy tests for the three samples of yogurt. Observig the curves it ca be cofirmed the highest values of viscosity for the CYT sample, followed by CYNT ad CY samples i this sequece, cofirmig the data obtaied i the viscosity curves. Also cofirmig the calculatios of hysteresis, there are greater reductios i the viscosity over time for CYNT, CYT ad CY samples, i that order. Table 7 presets the results of thixotropy test adjusted to Weltma model. The parameter A idicates the flow resistace, havig a close correlatio with the yield stress ( ), relatig with the shear stress at the time 1s. It ca be cofirmed that Herschel-Bulkley model was ot well adjusted to CYNT sample, because the value does ot match the value of the parameter obtaied by the model of Weltma. As for the CY ad CYT samples, the results are cosistet with each other, although the Weltma model has ot adequately described the thixotropy of the CY sample (r ² =.9226). The parameter B measures the speed of structural damage whe the fluid is subjected to ay shear rate. Negative values idicate a decrease i tesio due to the icrease of shear rate. It shows that the samples of coffee-flavored yogurt had the highest rates of structural breakdow. Thus, locust bea gum promotes a further decrease i the rate of breakdow of the gel. Goçalvez et al. 14 evaluated the rheological behavior of yogurt with differet cocetratios of starch ad gelati, as thickeers, as well as free yogurt thickeer. FIGURE 3 Curve of viscosity versus time of testig thixotropy of yogurt samples. Table 7 Parameters of Weltma model for the thixotropy test. A B r² CYT 16.61-5.24.9946 CYNT 15.13-5.9.987 CY 13.27-1.6.9226 526

The yogurts with gelati cocetratios of 3 ad 6 g L -1 showed discrepacies betwee ad A values. However, it is oteworthy that i their study, the r values were low for the Weltma model for both samples (r <.9). Also accordig to Goçalvez et al., 14 the values of parameters B calculated for the samples with gelati were seve times higher tha those obtaied i this work. This differece ca be explaied by the poor fit of the model of Weltma ad the results obtaied by them (r<.9). CONCLUSIONS All samples showed o-newtoia pseudoplastic ad thixotropic behavior. The three samples of yogurt with differet cocetratios ad types of thickeers showed differet rages of viscosity as a fuctio of shear rate. The CYT sample, which uses gelati as a thickeer, showed the highest viscosity values. The sample CYNT which did ot cotai a thickeer i the formulatio, showed the highest hysteresis value, idicatig greater structural damage uder processig. The Herschel-Bulkley model represets more accurately the flow curves of the three samples of yogurt. All values of flow idex () were less tha 1, cofirmig the pseudoplastic characteristic. Thickeers showed protective effect o the gel durig the flow, with lower hysteresis values for samples CYT ad CY. The Weltma model represeted well the thixotropy tests, except for sample CY (r² =.92). Thus, we ca coclude that the additio of gelati as thickeer aget promoted a icrease of viscosity ad cosistecy of the fial product, besides promotig major protective effect o the gel - factors that have great importace o the product acceptability. Whe compared with commercial yogurt, the coffee-flavored yogurt with gelati additio preseted satisfactory rheological properties. MATHIAS, T. R. S.; CARVALHO JUNIOR, I. C.; CARVALHO, C. W. P.; SÉRVULO, E. F. C. Caracterização reológica de iogurte sabor café com diferetes tipos de espessate. Alim. Nutr., Araraquara, v. 22,. 4, p. 521-529, out./dez. 211. RESUMO: Iogurte é um alimeto fucioal que apreseta grade demada devido à busca por uma vida e alimetação mais saudáveis. De forma a ampliar o mercado cosumidor, diversos são os sabores existetes, satisfazedo as mais variadas preferêcias. Além do sabor, a cosistêcia e viscosidade do iogurte são us dos pricipais fatores evolvidos a qualidade e aceitação do produto. Este trabalho é um estudo da ifluêcia do tipo de espessate em iogurte sabor café. O espessate utilizado foi a gelatia. O comportameto reológico (curvas de fluxo e de viscosidade) dos iogurtes com e sem adição de gelatia foram comparados etre si e com iogurte comercial, o qual utiliza outro tipo de espessate (goma alfarroba) em suas formulações. As curvas de fluxo e de viscosidade foram obtidas em reômetro rotacioal Thermo Haake Mars com variação de taxa de cisalhameto etre,2 e 1 s -1 (curva ascedete) e 1 e,2 s -1 (curva descedete) em um tempo total de 2 miutos. Foi determiada a histerese como a área etre as curvas e ajustados os modelos de Bigham, Casso, Herschel-Bulkley e Ostwald-de-Waele. Foram realizados também testes de tixotropia, pela medição da viscosidade em fução do tempo à uma taxa costate de 1 s -1, por 1 miutos. Estas curvas foram ajustadas pelo modelo de Weltma. Todas as amostras apresetaram comportameto pseudoplástico e tixotrópico. O modelo de Herschel-Bulkley foi o que melhor se ajustou às três amostras testadas. O modelo de Weltma descreveu bem os testes de tixotropia, com exceção para a amostra de iogurte comercial. O uso da gelatia como espessate apresetou caráter protetor, reduzido a quebra estrutural. PALAVRAS-CHAVE: Modelos reológicos; comportameto pseudoplástico; gelatia; estabilidade do gel; viscosidade. REFERENCES 1. ASSOCIAÇÃO BRASILEIRA DA INDÚSTRIA DO CAFÉ. O café brasileiro a atualidade. Dispoível em: http://www.abic.com.br/gar_qcafe.html. Acesso em: 4 ju. 29. 2. BRAHAM, J. E.; BRESSANI, R. (Ed.) Coffee pulp: compositio, techology ad utilizatio. Ottawa: IDRC, 1979. 96p. 3. BRANDÃO, S. C. C. Novas gerações de produtos lácteos fucioais. Rev. Id. Laticíios, São Paulo, v. 6,. 37, p. 64-66, 22. 4. BRASIL. Miistério da Agricultura, Pecuária e Abastecimeto. Istrução ormativa.46 de 23 de outubro de 27. Regulameto técico de idetidade e qualidade de leites fermetados. Diário Oficial [da] Republica Federativa do Brasil, 24 out. 27. Seção 1, p. 4-7. 5. BRASIL. Miistério da Agricultura, Pecuária e Abastecimeto. Regulameto técico para o café torrado em grão e para o café torrado e moído. Aexo 2: Características sesoriais do café. Rev. Cafeicultura, Rio de Jaeiro. Dispoível em: http:// www.revistacafeicultura.com.br/. Acesso em: 12 ju. 29. 6. CHANDAN, R. C. et al. Maufacturig yogurt ad fermeted milks. UK: Blackwell Publ., 26. 364p. 7. CHOU, T.M.; BENOWITZ, N.L. Caffeie ad coffee: effects o health ad cardiovascular disease. Comp. Biochem. Physiol. Part C - Pharmacol. Toxicol. Edocriol., v. 19,. 2, p. 173-189, 1994. 527

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38. TELES, C. D.; FLÔRES, S. H. Ifluêcia da adição de espessates e leite em pó as características reológicas do iogurte desatado. B. CEPPA., v. 25,. 2, p. 247-256. 27. 39. TONELI, J. T. C. L.; MURR, F. E. X.; PARK, K. J. Review: estudo da reologia de polissacarídeos utilizados a idústria de alimetos. Rev. Bras. Prod. Agroid., Campia Grade, v. 7,. 2, p. 181-24, 25. 4. WALSTRA, P.; WOUTERS, J. T. M.; GEURTS, T. J. Dairy sciece techology. 2 d ed. Boca Rato: CRC; Lodo: Taylor &Fracis, 26. 782p. Recebido em: 3/3/211 Aprovado em: 15/8/211 529