Studies on the Heat Expansion of Dried Starch Paste. Part 4

On the Heat Expansion of Various Starches

Abstract

The mechanism of heat expansion of the dried starch paste was investigated, and the following results were obtained. 1. The bulkiness of the expanded products of wheat and maize starch were increased by increasing the amount of water added to starch and extending the heating time . For any of the tested various starches, the higher the heating temperature, the larger the bulkiness of products. 2. The heat expansion rates of the dried starch paste as measured by the methods reported previously were 3.0-3.5 for wheat and maize, 4.7-5.0 for rice and waxy maize, and 5.8-7.0 for sweet potato, sago, tapioca and potato starches . The minimum hardness of the products was shown by the waxy maize starch (3 .0 kg/cm2), and the hardness of cereal starches were slightly higher than those of the others. 3. The optical and the scanning electron microscopical observations on the swelling and dispersion of granules, and of the internal structures of the baked products supported the above results. 4. It was recognized that the heat expansion rates of various starches were closely related to the physical properties (viscosity by amylograph, swelling power and elastic modulus of starch gels). The reason for the preferred use of potato starch in production of‘Ebi-Senbei’ (Shrimp cracker) was also discussed.