Phenolic antioxidants and antioxidant activity in pearling fractions of oat groats

To test the feasibility of dry milling oats (Avena sativa L.) to concentrate antioxidant activity and phenolic antioxidants, greats were pearled for 5 to 180 a. These treatments removed <1 to 15% of the weight. The material obtained from short pearling times was mostly bran. Longer pearling times increased the amount of starchy endosperm in the pearlings. Antioxidant activity of 80% ethanol extracts, measured by <beta>-carotene bleaching and by reduction of the free radical, 2,2-diphenyl-1-picrylhydrazyl, was highest in the short-pearling-time fractions and decreased as more endosperm tissue was 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 greats.-In contrast, concentrations of avenanthramides were not correlated with pearling time, indicating that they were more uniformly distributed in the greats. (C) 2001 Academic Press.