Author
 |
Emmons, Cheryld |
|
Peterson, David |
|
Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 7/22/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Researchers are striving to improve the nutritional value of foodstuffs. Many foods contain substances called antioxidants, which help protect cells from damage caused by stress, ageing, and toxic substances. We measured the contents of one class of antioxidants called phenolics in oats to determine how oats contribute to the antioxidant content of our diet. We also wanted to find where antioxidants were located in the oat kernel and to find out how much variability existed among different samples of oats. Among four samples analyzed, there were significant differences in the concentration of total phenolics and in concentrations of ten individual phenolics identified by chromatography. There were differences in the relative amounts of phenolics between the hulls and groats (edible portion). The results suggest that a wider survey of oat varieties will reveal those best suited to contribute dietary antioxidants or to serve as parents in a project to breed higher antioxidants into oats. We need to determine which phenolic compounds contribute most to the antioxidant activity in oats, so that we will know which ones we should attempt to maximize. This research will ultimately benefit the consumer, who will find more healthful oat products in the supermarket. Technical Abstract: Research was initiated to measure antioxidant activity of extracts from oat (Avena sativa L.) groats and hulls and the concentrations of phenolic substances that may contribute to antioxidant activity. Antioxidant activity of ethanolic extracts of four cultivars was evaluated by an in vitro assay that measures the inhibition of coupled autoxidation of linoleic acid and beta-carotene. Total phenolic content was determined using the Folin and Ciocalteau's phenol reagent and was expressed as gallic acid equivalents. Phenolic compounds were separated by reversed- phase high-performance liquid chromatography and detected at 290 nm. Peaks were identified by comparing retention times and spectra with known standards. Groats had significantly higher antioxidant activity than hulls. For two cultivars, total phenolic content was similar in groats and hulls, whereas one cultivar had higher and another lower total phenolic content in groats than hulls. Ten phenolic compounds were separated and identified in extracts, and one flavan-3-ol and three avenanthramides were tentatively identified. The concentrations of many of these compounds differed between cultivars and between fractions. In general, caffeic acid and the avenanthramides were predominantly found in groats, whereas many of the other phenolics were present in greater concentrations in hulls. |
