360 Differences in characteristics of starches isolated from non-waxy, partial waxy and waxy wheat.

B.-K. BAIK, Z. Czuchajowska, and B. Paszczynska. Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6376.

Prime starches isolated from non-waxy, partial waxy with one or two null waxy alleles, and waxy wheat genotypes were analyzed for their compositions, physical characteristics, thermal behavior and retrogradation properties. Isolated starches were highly pure with less than 0.4% protein and lower than 0.2% ash. Amylose content of prime starches ranged from 0.45 to 2.28% in waxy, 17.2 to 24.6% in partial waxy and 24.4 to 25.6% in non-waxy wheat. Pasting properties of starches were determined using a viscoamylograph and showed large differences between wheat genotypes. Peak temperatures of waxy starches were lower than 71 C, while those of partial waxy and non-waxy starches were higher than 92 C. Peak viscosity of prime starches was below 440 BU in non-waxy, ranged from 660 to 1040 BU in partial waxy and were over 1520 BU in waxy starches. Waxy starches formed the weakest gels, with lower than 0.7 N firmness, while firmness of gels prepared from partial waxy starches ranged from 2.0 to 6.6 N. Gels prepared from non-waxy starches had higher than 4.7 N firmness. Firmness of gels increased during 96 hr of storage by less than 0.3 N in waxy starches, 1.3 to 2.5 N in partial waxy and more than 1.9 N in non- waxy starches.