Effect of environmental temperature at the milky stage on amylose content and fine structure of amylopectin of waxy and nonwaxy endosperm starches of rice (Oryza sativa L.)

Starch granules were isolated from polished grains of rice plants (Oryza sativa L.), waxy and nonwaxy near-isogenic lines of a Japonica rice cultivar, Taichung 65, grown under controlled temperature conditions. Amylose contents and distributions of β-1,4 chains of amylopectin, and further details of the fine structure of waxy amylopectin were determined by enzymatic and chromatographic methods. The higher environmental temperature decreased amylose contents in endosperm starches of nonwaxy rice plants. Moreover, the higher environmental temperature increased the amount of long B chains of amylopectin and decreased mainly that of short B chains and slightly that of a chains as compared with the lower environmental temperature.