Studies on the Heat Expansion of Dried Starch Paste . Part 3.

Relations between the Physical and Chemical Properties and the Expansion Rate of Potato Starch

Abstract

The mechanism of heat expansion of the dried starch paste, the intermediate product of ' Ebi-senbei' (shrimp cracker), was investigated and the following results were obtained . 1. The heat expansion rate of the dried paste was proportional to each of the maximum viscosity in amylogram, the swelling power and the intrinsic viscosity, but was reciprocally proportional to the elastic modulus of starch gel. 2. The ratio of the combined phosphorus to total phosphorus was proportional to the expansion rate of the dried paste, while the smaller the total content of calcium and magnesium was, the larger the heat expansion rate became. 3. The stereoscopic microscopical observation of the internal fine structure of the baked products, (Ebi -senbei) supported the above results . 4. From these results, two basic factors were assumed for the mechanism of the heat expansion phenomenon of the dried starch paste. One was the extensibility of amylopectin which was dependent upon the physical and chemical properties of potato starch as well as upon the gelatinizing conditions in the preparation of the intermediate dried starch paste . The second was the positive internal pressure produced by water and air contained in the intermediate dried pasteupon heating. The related industrial problems were also discussed.