Abstract:Wheat bran was modified by yeast fermentation.The changes of soluble dietary fiber and other substances in wheat bran after yeast fermentation were studied，and the technology of wheat bran fermentation was optimized to increase the content of soluble dietary fiber in wheat bran.The single-factor experiment showed that the soluble dietary fiber content in bran was the highest when the solid-liquid ratio was 1 ∶10（g/mL），fermentation temperature was 30 ℃and fermentation time was 24 h.Based on the results of single-factor experiments，the interaction of fermentation，fermentation time and solid-liquid ratio and their effects on soluble dietary fiber content in bran were studied by response surface methodology.The results showed that the effects of three factors on the content of soluble dietary fiber in bran had obvious interaction.The optimum conditions for wheat bran fermentation were that fermentation temperature 29 ℃，fermentation time 25 h，solidliquid ratio 1 ∶12 （g/mL）.Under these conditions，the yield of soluble dietary fiber was 20.21 %.The composition of the wheat bran before and after fermentation was compared.It was found that the content of protein and ash in the wheat bran after fermentation increased，and the content of starch and oil decreased.The water holding capacity and swelling property of wheat bran were significantly increased after fermentation.