33A-25 |
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Y.-C. TSENG, Department of Animal Sciences, University of Kentucky, 103 W.P. Garrigus Building, Lexington, KY 40546 and Y. L. Xiong, Dept. of Animal Sciences, University of Kentucky, Lexington, KY 40546. Inulin, a fructan containing mostly beta(2-1) linkages with a degree of polymerization between 2-60, has been used as a prebiotic. As a soluble dietary fiber, inulin can also be used as a fat replacer or texture modifier. Little is known about the role of inulin in the texture of soy-based products. The objective of this study was to examine the effect of inulin on the viscoelastic properties of silken tofu using glucono-delta-lactone as a coagulant. Whole soybeans were rinsed and soaked in tap water overnight. Fully hydrated soybeans (250 g) were ground in tap water (500 mL). After removing the okara, homogeneous raw soymilk was boiled for 6 minutes and then cooled to room temperature. Inulin was added to the preheated soymilk at 0, 1, 2, 3 and 4% (w/w) levels along with 0.4% (w/w) glucono-delta-lactone. Samples were subjected to oscillatory shear analysis using a Bohlin VOR rheometer. Gelation was induced by heating the samples from 20°C to 90°C at a constant rate (1°C /min). Storage modulus (G’), loss modulus (G”), pH, and temperature were constantly recorded. The rheological changes in soymilk were related to both the pH decline (release of hydrogen ions) and the specific temperature of heating. Both the G’ and G” values of all samples increased upon heating to 35°C, indicating formation of a viscoelastic tofu gel network. The addition of inulin improved (P < 0.05), in a dose-dependent manner, the gelling ability of the acidulated soymilk. For example, compared to control sample (inulin-free), the sample treated with 4% inulin had 46% and 34% improvements (P < 0.05) in G’ and G” respectively, at the end temperature (90°C). Results indicated that inulin is capable of enhancing the elasticity of silken tofu gel using glucono-delta-lactone as a coagulant, which is an added benefit to its current application mainly as a prebiotic health ingredient in food.
Session 33A, Carbohydrate: General
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