Abstract
The composition of rice endosperm starch is classified into several types, based on the proportion of amylopectin short chains (L-type and S-type) and the contents of amylose and amylopectin with super-long chain (SLC) (K-type, H-type and Y-type). We investigated the correlation of these starch compositions with rice flour characteristics and the shape of starch granules using 27 rice cultivars including three near-isogenic lines of Nipponbare (Nipponbare NILs) with different starch compositions. Rice endosperm starch was classified into 6 types; KS, KL, HS, HL, YS and YL based on the amylose and amylopectin composition. Mean granule (partial) diameter of rice flours was smaller in high SLC type (Y<K). The amount of damaged starch was smaller in the low proportion type of amylopectin short chains (YL<YS, HL<HS) and high SLC type (YL<HL, YS<HS). The water absorption had a negative correlation with amylose content. Unpolished rice whiteness of Nipponbare NILs was higher in the L-type. The size and shape of starch granules observed by scanning electron microscopy varied with the type of starch composition. We suggested that the structure of the starch granules affect unpolished rice whiteness and rice flour characteristics.
