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Title: STRUCTURE AND PHYSICOCHEMICAL PROPERTIES OF STARCHES FROM SIEVE-FRACTIONS OF OAT FLOUR COMPARED TO WHOLE AND PIN-MILLED FLOUR

Author
item Stevenson, David
item JANE, JAY-LIN - IOWA STATE UNIVERSITY
item Inglett, George

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2006
Publication Date: 11/1/2007
Citation: Stevenson, D.G., Jane, J., Inglett, G.E. 2007. Structure and physicochemical properties of starches from sieve-fractions of oat flour compared to whole and pin-milled flour. Cereal Chemistry. 84(6):533-539.

Interpretive Summary: Oats grown in Idaho had starch characteristics compared without and with pin-milling, and subsequent separation into three sieve sizes, to determine if starch separated from large sieve size containing the nutritionally beneficial beta-glucans has different properties to starch from remaining sieve sizes. Majority of starch characteristics were not different among sieve sizes but starch paste viscosity was lower in medium size sieve fraction compared with larger and smaller size sieve fractions. Pin-milling was also found to lower apparent amylose content and shorten amylopectin branch chain-lengths compared with starch from kernels without pin-milling. This study found potential new applications for starch separated during beta-glucan enrichment that improves the overall economics of producing the nutritionally beneficial beta-glucan ingredients.

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