Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2000
Publication Date: N/A
Interpretive Summary: Oats and other cereals contain phytonutrients that have health promoting and disease preventing properties. If the concentrations of these substances could be increased, their effects would be even better. This might be done by genetics and plant breeding, but another approach is by milling to produce fractions whose phytonutrient content is enhanced. This study looked at the effects of pearling (abrading successive layers from the surface) oat groats to produce fractions that are enriched in the tissues from the outer surface of the grains. By pearling for increasing times, more of the kernel mass was removed. These fractions were analyzed for the content of some antioxidant compounds and for a measure of total antioxidant activity. We found that the highest activity and greatest concentrations of most of the antioxidants were in the fractions produced with the least pearling time. However, one class of antioxidants called avenanthramides was more evenly distributed throughout all fractions. The impact of this study is to show the possibility of using a dry milling technique to produce oat fractions that contain more health promoting substances. These fractions could be used to produce marketable food products.
Technical Abstract: As an approach to determining the feasibility of dry milling to concentrate antioxidant activity and phenolic antioxidants from oats (Avena sativa L.), groats were pearled for various lengths of time, which removed quantities ranging from <1 to 15% of the weight. The pearling samples obtained from short pearling times contained predominantly surface layers, whereas those obtained from longer times, contained additional layers of tissue. Antioxidant activity of 80% ethanol extracts of the samples, measured by beta-carotene bleaching and by the reduction of the free radical, 2,2-diphenyl-1-picrylhydrazyl, was highest in the short-pearling-time fractions and decreased as greater amounts of groat tissue were included. Likewise, there was a decreasing concentration of total phenolics, determined colorimetrically, and of several simple phenolic acids, determined by high performance liquid chromatography, as more material was pearled from the groats. In contrast, concentrations of avenanthramides were not correlated with pearling time, indicating that they were more uniformly distributed.