Physicochemical properties and digestibility of endosperm starches in four indica rice mutants

Structural, physicochemical characteristics and digestibility of endosperm starches from four mutants (GM01, 03-05) and their parent Guangluai 4 (GLA4) were characterized. GM05 had a little higher apparent amylose content (AAC) and showed little difference in starch and digestion properties from GLA4. However, GM03 and GM04 with increased amount of chalkiness and partial translucent region in the endosperm displayed a distinct starch and digestion properties, which had the RS of 7.9 and 8.4%, respectively. GM03 and GM04 had higher AAC (33-35%), lower degree of crystallinity, lower gelatinization temperature and pasting viscosities, and more amount of B1 (DP 12-24) and B2 (DP 25-36) chains and less amount of B3 chains (DP >= 37) in amylopectin. AAC and the amount of B1 chains had positive correlation with RS, but the amount of B3 chains had negative correlation with RS. The results of this study may be applied to design RS by selecting rice germplasm with high AAC and high amount of B1 chains (DP 12-24) of amylopectin.