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Strawberry-flavored probiotic dairy beverages (2% vol/vol Lactobacillus acidophilus) were produced using 0, 20, 35, 50, 65, and 80% (vol/vol) whey in their formulations. Mathematical models (survival analysis, minimal significant difference, and mean global acceptance) were used to identify the optimal (sensorially) whey concentration in probiotic beverages. Fifty-five consumers evaluated acceptance of the beverages using hybrid 9-point hedonic scales. In addition, Lb. acidophilus were enumerated and pH was determined. Rheological behavior is an important characteristic for the processing and sensory acceptance of dairy beverages, varying with the presence of additives, fermentation process (time, bacterial strain), and whey concentrations used. All beverages presented minimal counts of 8 log cfu/mL of Lb. acidophilus, and pH ranged from 4.09 to 4.14. Increasing the whey content increased the fragility of the gel structure, probably because of the replacement of casein by whey proteins, once the concentrations of other ingredients in formulation were fixed. Whey content had a significant effect on acceptance of the probiotic dairy beverages; beverages with whey contents greater than 65% resulted in lower acceptance by consumers. The model of mean global acceptance presented 2 solutions with high sensory scores: beverages with 12 and 65% whey, the latter being of interest because it allows greater use of the whey by-product. The Weibull distribution presented a prediction of whey concentration of 49%, with higher sensory acceptance. The methodologies used in this research were shown to be useful in determining the constituents of food formulations, especially for whey-based probiotic beverages.

IntroduçãoProdutos elaborados, como molhos para salada, conservas, sobremesas, pratos prontos, dentre outros, passam por alguma etapa de bombeamento, esterilização, congelamento ou acidificação, durante o processamento. Um aditivo amplamente empregado nestes alimentos é o amido, utilizado na indústria de alimentos como agente espessante e gelificante (KUhN;SChLAUCh, 1994;MARqUES et al., 2006). Para resistir a estas condições estressantes, os amidos devem conservar suas propriedades funcionais como a textura inicial, não liberar água nem alterar cor, preservar aromas, resistir a ph baixo e a esterilização e ainda aumentar a vida de prateleira do produto. Em geral, o uso de amido nativo é limitado devido às perdas ou ao decréscimo de propriedades funcionais apresentando uma baixa resistência à tensão de cisalhamento, uma propensão à decomposição térmica e uma alta retrogradação e sinérese, que podem ocorrer durante ou após o processamento. Essas falhas podem ser superadas pela modificação do amido por métodos químicos, físicos ou enzimáticos. Os amidos são constituídos essencialmente por 2 α-poliglucanas, a amilose e a amilopectina. A amilose, que é uma molécula essencialmente linear de ligações (1→ 4) -α-D-glucose com um pequeno grau de ramificações (TAKEDA et al., 1987). A amilopectina é uma molécula altamente ramificada, na qual cadeias de (1→ 4)-α-Dglucanas são conectadas por ligações α(1→ 6) (ELLIS et al., 1998) com cadeias curtas como dupla hélice em clusters de caráter parcialmente cristalino (ZObEL, 1988, SINGh et al., 2003. O amido, quando aquecido em excesso de água, gelatiniza, passando por uma fase de transição de ordem-desordem, em que ocorrem a hidratação, a expansão e o rompimento granular e, ainda, a solubilização das moléculas de amido. Os géis de AbstractStarches are widely utilized in foodstuffs as salad dressing, sauce, and processed foods. however, the functional properties of native starches are affected by processes such as heat treatment, acidity, and high shear stress. Starches can be modified chemically in order to have characteristics required by industries, but not to attribute the food a "natural and safe" label. Another option is to obtain native starches resistant to food processing stress conditions. The objective of this paper is the evaluation of commercial native organic starches under food processing stress conditions such as heat treatment and acidity. Suspensions of native functional organic starches (9460 and 9560, National Starch, and Chemical Industry) were prepared at 5% concentration (w/v), acidified with 1M citric acid, or autoclaved at 121 °C for 30 minutes. The results were evaluated by optical microscopy, flow curve, and viscoelastic aspects which were obtained by steady and oscillatory rheology. The acidity and heat treatment increased the starch gels structure that resisted to the processing stress conditions. The starch gels exhibited non-newtonian (pseudoplastic) and thixotropic behavior. Flow data were fitted to the Power Law or herschel-bukley models. All sample...

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