Comparison of six modification methods on the chemical composition, functional properties and antioxidant capacity of wheat bran

The effects of six modification methods (microwaving, steam, extrusion, superheated steam, fermentation and enzymatic treatments) on the chemical composition, processing quality characteristics and antioxidant capacity of wheat bran were determined. Compared with unmodified control bran, all six modification methods had a significant impact on the physical and chemical properties and antioxidant capacity. Microwaving, steam, extrusion, superheated steam and enzymatic treatments could significantly increase the content of folic acid, but decreased the content of vitamin B2. Fermentation increased the proportion of soluble dietary fiber and changed the ratio of insoluble/soluble dietary fiber from 13.65:1 to 8.74:1. The content of water extractable arabinoxylan after microwaving, extrusion and fermentation increased by 12.3%, 33.6% and 46.4%, respectively. Extrusion increased the swelling force of the bran. All modifications increased the total phenolic and ferulic acid contents and the bound ferulic acid content was highest after the steam and extrusion treatments. Enzymatic treatment reduced the DPPH radical scavenging capacity by 16.9%, microwaving increased the ABTS radical scavenging capacity by 12.53% and extrusion increased the ORAC(oxygen radical absorbance capacity) by 4.15%. Overall, extrusion resulted in the greatest improvements in the nutritional and processing qualities of bran, and the greatest increases in its phenolic content and antioxidant capacity.