Abstract: High quality wheat bran dietary fiber (DF) has been reportedly by microbial fermentation to decompose, convert and utilize celluloses, proteins and starches in wheat bran. The effects of fermentation with individual and mixed strains of R. oryzae, T. reesei and A. niger on the contents of soluble and insoluble dietary fiber (SDF and IDF) was examined. An orthogonal array design was employed to optimize process parameters for mixed strain fermentation. The results indicated that mixed strain fermentation was better than single strain fermentation. The SDF content was increased from 11.74% to 86.94% by fermentation with a 10% inoculum (T. reesei:A. niger = 1:1) at a material-to-liquid ratio of 1:10 and 32 ℃. The obtained product showed a water-holding capacity of 9.34 g/g and a swelling property of 12.46 mL/g and met the requirements of high quality dietary fiber.

Key words: fermentation, wheat bran, dietary fiber