A Comparative Study on Retrogradation of Rice Starch Gels by DSC, X‐Ray and α‐Amylase Methods

Abstract

Abstract The degree of retrogradation (DR) of 10 and 50% rice starch gels, which were stored at refrigerator, room temperature and freezer for 1, 3 and 6 days, were investigated by DSC, X‐ray diffractometry and α‐amylase‐iodine methods. Besides being affected by moisture content and storage conditions applied, the nonwaxy rice starch gels were retrograded faster and higher than the waxy ones. DR of 50% starch gels was higher than that of 10% starch gels. In case of 50% starch gels DR increased in the following order: refrigerated < room temperature < frozen. For 10% starch gels, no typical X‐ray pattern of the retrograded starch was shown, while DSC and α‐amylase‐iodine method gave information on DR of starch gels. Due to interpretative sensitivity of the data obtained, α‐amylase‐iodine method was suggested as an adequate mens for the DR of starch gels.