Structural and functional characteristics of Japonica rice starches with different amylose contents.

Fully understanding the structures and properties of starches with different amylose contents is important to agriculture and food industries. Structural and functional characteristics of three Japonica rice starches differing in amylose content (<0.5%, 18.8%, and 33.3% for waxy, normal, and high-amylose varieties, respectively) were investigated using a range of characterization methods. As amylose content increased, the weight-average molecular weight, short-range order, relative crystallinity, and lamellar peak intensity of starch decreased. High-amylose starch contained a lower proportion of A chains than waxy and normal starches. High-amylose starch displayed a C-type crystalline structure, different from the A-type crystalline structure of waxy and normal starches. Compared with waxy and normal starches, high-amylose starch exhibited higher granule size (volume-average diameter), pasting temperature and higher resistant starch content, but lower peak viscosity, breakdown viscosity, swelling power, and rapidly digestible starch content. These results can provide reference for the exploitation of Japonica rice starches. [ABSTRACT FROM AUTHOR]