Enhancement of polyphenol content and antioxidant capacity of oat (Avena nuda L.) bran by cellulase treatment

In this work, cellulase was used to treat with oat bran, and its effect on the total polyphenol content and phenolic profiles were investigated, with heating-only treatment as the control. Antioxidant capacity of the phenolic extracts from oat bran was assessed by scavenging of 2,2′-azinobis (3-ethylbenzothiazoline-6- sulphonic acid), 2, 2-diphenyl-1-picrylhydrazyl radical cation, the ferric reducing antioxidant power, and protein oxidative damage protection assays. As a result, cellulase treatment significantly increased the total phenolic content, total antioxidant capacity, and the ability on the protection of protein from oxidative damage of the oat bran compared with heating-only treatment. Furthermore, cellulase treatment significantly increased availability of most phenolic compounds, except of gallic acid, such as caffeic acid by 97 % (5.33 vs. 10.51 μg g⁻¹), vanillin by 28 % (3.32 vs. 4.24 μg g⁻¹), p-coumaric acid by 105 % (5.55 vs. 11.35 μg g⁻¹), and ferulic acid by 914 % (12.33 vs. 124.03 μg g⁻¹). However, heating-only treatment had no significant influence on the five detected phenolic compounds. Therefore, the study revealed that cellulase treatment would produce polyphenol-rich oat products with increased antioxidant activity.