| Wheat bran is a by-product of wheat processing, which is a representative and combine the health benefits of dietary fiber resource compounds. However, low soluble dietary fiber (SDF) content-limited the application of wheat bran in food processing. Degradation treatment on wheat bran not only can increase its SDF content, it also can improve the physical and chemical properties, as a healthful and safety additive for food.This paper selects Rhizopus oryzae as an inoculant, optimization of the incubation conditions of liquid and solid state fermentation respectively.Taking the soluble dietary fiber yield as the index, Box-Bchnken optimization design was conducted to the further research based on the results of single factor experiments of liquid state fermentation,namely, inoculum and the fermentation time and solid-liquid ratio. When the inoculums size was 10.33%, solid-liquid ratio was 1:21.06 and fermentation time was 103.82 h, the SDF yield could reach 9.71%. At the same optimization incubation conditions of solid-state fermentation, namely, water content and inoculum and the fermentation time, the water content was 51.74%, inoculum size was 9.73% fermentation time was 123.85 h, the SDF yield could reach 8.48%. It was no significant difference in two fermentation processes from the extraction yield of the SDF. Solid state fermentation technology is simple and low energy consumption, it’s the best choice for fermentation is solid-state fermentation.The physical and chemical indicators changing of wheat bran in the process of solid-state fermentation was studied. The content of total sugar showed a trend of decrease in general, while the soluble protein and total protein were on the contray. Free amino nitrogen and reducing sugar content had a trend of lower after rising.The paper compared the physical and chemical properties of SDF in the wheat bran through solid-state fermentation and unfermented SDF, SEM observation showed that SDF were closely aggregated, laser light scattering observed particle size becomes smaller. Increased solubility in water, the solution transparency, thermal stability, water holding capacity, the expansion force also increases.Rheometer and GC determined the fluid properties and srtucture of SDF. Results showed that SDF of pseudoplastic fluid, belongs to the non-newtonian fluid, the results showed that monosaccharide composition was composed of Ara, Xyl, Man, Gal, Glu, the molar ratio is 6.87:8.93:1:1.1:4.70.Texture analyzer determined the effect of different proportions of soluble dietary fiber on the texture of the noodles, the results showed that with the increase in the proportion of soluble dietary fiber, compared with the control noodles elasticity decreased, other indicators chewiness, gumminess resistance, resilience were no significant changes. When the SDF content was 8%, the cohesiveness decreased, it is showed that dietary fiber added to noodles will not affect the quality and it also has the effect on health. |
