Structure and physicochemical properties of starches from sieve fractions of oat flour compared with whole and pin-milled flour.

摘要

One oat cultivar grown in Idaho (three field sites) was pin-milled and separated by sieving to investigate whether starch from oat bran differs from the remainder of kernel. Ground oat particles were classified into three sieve fractions: 300-850 micro m, 150-300 micro m and <150 micro m. beta -Glucan content in sieve fractions was analyzed and starch was extracted from kernels without milling and from kernels of each sieve fraction. beta -Glucan contents of 300-850, 150-300, and <150 micro m sieve fractions were 4.2, 2.3, and 0.8%, respectively. Therefore, starch in bran (300-850 micro m sieve fraction) and endosperm (<150 micro m sieve fraction) were separated. Starch isolated from entire kernels had significantly higher apparent and absolute amylose content than starch from the 300-850 micro m sieve fraction. Starch from different sieve fractions was not significantly different in the apparent amylose, absolute amylose, amylopectin molecular weight, gyration radii, starch gelatinization, and amylose-lipid complex thermal transition temperatures. Starch from the 150-300 micro m sieve fraction had significantly lower peak, final, and setback viscosity compared with the starch isolated from the 300-850 micro m and <150 micro m sieve fractions. Starch removed from the oat bran fraction during beta -glucan enrichment may have different applications compared with starch obtained from other kernel compartments. Because pin-milling decreased apparent amylose content and shortened amylopectin branch chains, its potential to alter starch structure should be considered.