Effect of Microbial Fermentation on Content,Composition and Antioxidant Activity of Water-soluble Polyphenols in Wheat Bran

This study analyzed the effects of different fermentation time,fermentation temperature and ratio of feed to liquid on the content of water-soluble polyphenols in wheat bran,and compared the composition and antioxidant activity of water-soluble polyphenols in wheat bran.The results showed that the mixed fermentation of Bacillus subtilis and Saccharomyces cerevisiae could increase the content of water-soluble bran polyphenols,and the content of water-soluble bran polyphenols reached(13.41±0.10) mg/g,294.41% higher than that before fermentation,when the ratio of liquid to material was 1:1,the fermentation temperature was 37℃,and the fermentation time was 84 h.Fermentation could increase the content of free and bound ferulic acid to 20.22 mg/kg and 1160.6 mg/kg respectively,and the water-soluble bran polyphenols mainly existed in the form of bound ferulic acid.Studies on antioxidant activity showed that after microbial fermentation,the reducing power and DPPH free rodical scavenging rate of bran polyphenols significantly increased,but the hydroxyl radical scavenging rate decreased.Therefore,microbial fermentation can improve the content of polyphenols in water-soluble bran,change its composition,enhance the antioxidant activity,and provide a basis for the effective use of polyphenols in wheat bran.