关键词: 杂粮, 抗氧化活性, 多酚, 黄酮

Abstract: Purpose: To compare the contents and existence form of polyphenols and flavonoids as well as antioxidant activities of edible parts between minor cereals (common buckwheat, tartary buckwheat, oat, coix, millet, corn and proso millet) and staple food grains (rice and wheat), and to explore the correlations between antioxidant properties and total phenolics or flavonoid contents. Methods: Total phenolic content was measured by Folin-Ciocalteu assay, and the content of total flavonoids was investigated by NaNO2-Al(NO)3 assay. Antioxidant properties were evaluated by DPPH free radical and ABTS+ · scavenging assay, reducing power and β-carotene-linoleic acid emulsion assay. Results: The content of total phenolics revealed a decreasing order as tartary buckwheat ＞ common buckwheat＞ at＞coix ＞ corn＞millet＞ proso millet＞ wheat ＞ rice. Except for millet and proso millet, the major existence form of polyphenols was free phenolics (64.18%－98.70%). Additionally, the content of total flavonoids was the highest in coix, followed by oat, and existed mostly in a free form in both of them. The DPPH free radical and ABTS+ · scavenging capacity and reducing power of tartary buckwheat were higher than those of other cereals, while millet had the highest AAC value as determined by β-carotene-linoleic acid assay. In the present study, a significant correlation was observed between total phenolics and antioxidant activity. Conclusion: The antioxidant properties of minor cereals were higher than those of staple food grains, with the best antioxidant capacity in tartary buckwheat. Therefore, it can be suggested that minor cereals should be eaten more to improve the intake of dietary polyphenols, which are present in staple food grains in excessively small amounts.

Key words: minor cereal, antioxidant activity, phenolics, flavonoids