Phenolic composition and antioxidant activity of colored oats

Phenolic composition and antioxidant capacity of 20 oat genotypes differing in hull color were investigated. Phenolic aldehydes, phenolic acids, avenanthramides and mono-, and diglycerides were identified in the soluble phenolic fraction of the genotypes. The bound phenolic fraction proved to be less diverse with phenolic aldehydes, phenolic acids and a ferulic acid dehydrodimer detected. Investigating the scavenging capacity of the hull and groat toward 2,2-diphenyl-1-picrylhydrazyl (DPPH), an increased antioxidant activity (AOA) of hull compared to groats and a color dependence of the hull AOA could be observed. Principal component analysis on the determined variables revealed that the black-hulled samples were different from the white ones due to their increased phenolic content detected in the hull. However, reddish-hulled varieties were grouping with the accessions of the other colored groups. In addition, a distinction between spring and winter cultivars was also observed.