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Title: STRUCTURE AND PHYSICOCHEMICAL PROPERTIES OF DEFATTED AND PIN-MILLED OAT BRAN CONCENTRATE FRACTIONS SEPARATED BY AIR CLASSIFICATION

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

Submitted to: International Journal of Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2007
Publication Date: 6/1/2008
Citation: Stevenson, D.G., Eller, F.J., Jane, J., Inglett, G.E. 2008. Structure and physicochemical properties of defatted and pin-milled oat bran concentrate fractions separated by air classification. International Journal of Food Science and Technology. 43:995-1003.

Interpretive Summary: Oat bran concentrate was defatted by supercritical carbon dioxide, pin-milled and then separated into five particle-size fractions by air classification. Beta-glucan content increased and starch content decreased in fractions with increasing particle size. Higher particle-size fractions required substantially higher paste viscosity and higher temperatures to melt starch than the lower particle size fractions. Air classification of oat bran concentrate will provide ingredients with a wider range of food applicaitons to help increase sales of the food industry.

Technical Abstract: Oat bran concentrate (OBC) was defatted by supercritical carbon dioxide, pin-milled and air classified into five fractions (less than 15 micrometer, 15-18 micrometer, 18-24 micrometer, 24-30 micrometer and greater than 30 micrometer). Beta-glucan content (% dry weight) of defatted OBC, its subsequent pin-milling, and the air classified fractions in ascending particle size was 14.3, 17.0, 4.3, 5.8, 12.6, 14.7, and 22.4, respectively. High-performance size-exclusion chromatography equipped with multi-angle laser-light scattering and refractive index detectors showed amylopectin was the predominant molecule present in all OBC powders, but was present in greater concentration in fractions collected that were less than 24 micrometer. Fractions greater than 24 micrometer, which had the highest beta-glucan contents had higher starch gelatinization temperatures (measured using a differential scanning calorimeter), and had substantially higher peak, breakdown, final and setback paste viscosity (measured using a Rapid Visco Analyzer) compared with the other lower-beta-glucan containing fractions. No differences in water retention of 25% (w/w) oat powders in water (measured using thermogravimetric analyzer) were observed among defatted OBC, its subsequent pin-milling, and the five fractions separated by air classification. In particular, differences in pasting properties shows that defatted, pin-milled OBC that is fractionated by air classification will have different food applications depending on particle size collected.