33A-4 |
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L. L. NIBA, Dept. of Human Nutrition, Foods & Exercise, Virginia Polytechnic Institute & State Univ., 319 Wallace Hall, Mail Code 0430, Blacksburg, VA 24061-0430 and Z. Yan, Human Nutrition, Foods & Exercise, Virginia Tech, 337 Wallace Hall, Blacksburg, VA 24061. Consumption of whole grains is recommended due to their high levels of beneficial components such as soluble fibers and antioxidants. Quality of grain flours is however impacted by their functional characteristics. Whole wheat flour viscosity, for instance, influences intestinal transit and colonic fermentation. Hydrocolloids are typically used to improve functionality. The objective of this study was to compare the effects of varying levels of hydrocolloids on pasting, shear-thinning and syneresis properties of whole wheat flour suspensions. Guar gum, gum arabic, inulin, konjac or xanthan gum was added to whole wheat flour (concentrations: 0.75 %, 1.5 %, 3 % or 5 %). Pasting and shear-thinning properties of whole wheat flour or flour-hydrocolloid mixtures were determined by holding at 95 °C for 30 minutes after the onset of gelatinization in a Brabender Microviscoamylograph (adaptation of Subrahmanyam and Hoseney, 1995). Syneresis tendency was determined by the procedure of Tovar and others (2002). Increasing guar, konjac or xanthan gum levels increased the mean maximum viscosity of whole wheat flour (149 BU to 724 BU with 5 % konjac gum). Increasing gum arabic or inulin levels decreased maximum viscosity. Gelatinization temperature was lowest with xanthan gum. Shear-thinning percentage was modified by addition of hydrocolloid. Degree of syneresis in stored wheat flour gels (3.73 %) was modified by guar gum, gum arabic or xanthan gum. Xanthan gum greatly reduced degree of syneresis. It is apparent therefore, that addition of these hydrocolloids influences pasting characteristics of whole wheat flour, possibly as a result of physical and chemical interactions. However, other than with xanthan gum, up to 5 % levels of the other gums tested do not inhibit syneresis in stored whole wheat flour gels. This is relevant in determining suitable processing and storage conditions for whole wheat flour in food products.
Session 33A, Carbohydrate: General
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