Starch Properties and Structure of A Wheat Mutant High in Resistant Starch

Abstract

Starch properties and structure of a wheat mutant (WRS-1) high in resistant starch (RS) was compared to that of the wild type (Sumai No.6). In cooked hot flour and retrograded flour, the amounts of RS in mutant WRS-1 were 7.8 and 9.4 times of wild type (0.5 in hot flour and 0.6 in retrograded flour), respectively, and correspondingly the slower and incomplete starch hydrolysis was also in both types of samples. WRS-1 had a higher λmax of absorbance, blue value (BV), apparent amylose content (AAC), and contained the increased intermediate and long chains with 18≤ degree of polymerization (DP) and decreased short chains with DP≤17. Two types of starch granules, large A in lenticular shape and small B in spherical shape, were observed in both mutant and wild types. However, the starch granules in WRS-1 were relatively larger and some were irregularly-shaped. High content of total starch (TS), decreased contents of lipid (LC) and protein (PC), lower onset temperature (To), peak temperature (Tp), final temperature (Tc), and the enthalpy of gelatinization (ΔHgel) were observed in WRS-1.