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J. N. BEMILLER, Whistler Center for Carbohydrate Research, Purdue Univ., Dept. of Food Science, 1160 Food Science Bldg., West Lafayette, IN 47907-1160 Pasting curves of starches in gum/hydrocolloid solutions at low concentrations revealed that gums produced a variety of effects, i.e., increased or decreased greatly or slightly or no effect on viscosity. A viscosity increase before the normal starch pasting temperature was detected for normal maize starch in the presence of CMC, gellan, xanthan, guar gum, and sodium alginate. Waxy maize, waxy rice, normal rice, tapioca, potato, and wheat starches gave mixed responses. The peak viscosity of potato starch was greatly decreased by negatively charged gums, viz., CMC, carrageenans, alginates, and xanthan. (Work done by Xiaohong Shi.) Waxy maize and potato starches were dispersed in pH 6.0 and pH 8.0 aqueous solutions of an anionic gum (alginate, CMC, and/or xanthan). The mixture was dried , then heated 2 hr in an oven. Heating with sodium alginate or sodium CMC increased the paste viscosity of waxy maize starch, but reduced that of potato starch. In both starches, xanthan effected greater viscogram changes than did sodium alginate or CMC. The pH of the starch-gum mixtures affected the thermally-induced viscosity changes. By using gum mixtures, such as xanthan/alginate and xanthan/CMC, both viscosity increase and good shear stability were achieved. (Work done in collaboration with Seung-Taik Lim by Hyesook Lim and Jung-Ah Han.)
Session 4, Impact of starch-hydrocolloid interactions in food systems
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