Antioxidant activity, avenanthramide and phenolic acid contents of oat milling fractions

Avenanthramide (AV) 2a, 2p and 2f as well as five phenolic acids (vanillic, caffeic, p-coumaric, ferulic, and p-cinnamic) were quantified by LC–MS in six oat milling fractions (medium bran (MB), fine bran (FB), low bran (LB), whole oat groat flour (WF), 15% (15HG) and 20% high glucans). AVs content ranged from 323.7 to 775.5 μg/g while the free phenolic acids content was much lower 103.5–194.6 μg/g. The extraction procedure used greatly increased the concentration of identified molecules compared to previous data. FB had the highest content of both groups of phenols while WF contained the lowest. The peroxyl radical scavenging assay showed that granulation had no effect of on scavenging power as MB (31.8 ± 2.3 μM TE/g) and FB (27.7 ± 2.1 μM TE/g) had similar activities. Radical scavenging data correlated with AVs content but not with free phenolic acids, demonstrating that AVs were the main antioxidant compounds. The identity of quantified molecules was confirmed by mass spectrometry.