Hysteretic Effect of Step by Step Heating on the Restriction of Gelatinization of Legume Starch

Abstract

AbstractThe restriction of gelatinization of the legume starches, which were isolated from Phaseolus vulgaris species, was studied in terms of enzymatic digestion, light microscopic observation, measurements of X‐ray diffraction, viscosity, swelling power and solubility, when the legume starch slurries were heated in step by step manner at a given rate from moderate temperature up to 90°C. Three legume starches tested showed a remarkable restriction of gelatinization, although these phenomena were not always observed in the legume starch slurry alone. Such restriction of gelatinization, however, was not observed in the waxy starch or starches which contain few amylose fractions. The formation of starch‐lipid complex was ruled out as a cause because the defat treatment did not reduce the restricted gelatinization of legume starch and high amylose corn starch. From the data presented, it was suggested that physical modification of starch slurry containing amylose fraction induced the hysteretic, mutual alteration of the starch macromolecules.