Effects of Solid-state Fermentation of Lactic Acid Bacteria on the Physical, Structural and Functional Properties of Soluble Dietary Fiber from Highland Barley Bran

To investigate the improvement of the physical, structural and functional properties of soluble dietary fiber (SDF) from highland barley by lactic acid bacteria solid fermentation, this study used single bacteria (Bulgarian lactobacillus, Thermophilic streptococcus) and mixed bacterias (Bulgarian lactobacillus:Thermophilic streptococcus=4:2) to ferment highland barley bran. Then, the highland barley bran SDF was prepared by enzymolysis. Meanwhile, the effects of solid-state fermentation of lactic acid bacteria on the physical, structure and function of SDF in highland barley bran were studied. After fermentation, the yield of SDF in highland barley bran was improved. The highest yield of SDF was 12.24 g/100 g in the mixed bacteria treatment group, which was 27.4% higher than that in the non-fermentation treatment group. Compared with single bacteria fermentation, the mixed bacteria fermentation increased the water holding capacity, oil holding capacity and solubility of SDF from highland barley bran (6.38 mL/g, 0.81 g/g, 83.89%, respectively). The surface structure of highland barley bran SDF was loose and porous, the crystal structure and the groups were not changed, and the thermal stability was decreased. The results of functional analysis showed that SDF from highland barley bran after fermentation had strong lipid lowering activity, antioxidant ability and inhibition ability of sugar-digesting enzyme. The cholesterol adsorption capacity of SDF in the mixed bacteria fermentation group reached the maximum (0.27 mg/g) when pH=7, as well as the adsorption rates of sodium taurocholic acid (28.92%) and sodium glycyrcholic acid (36.24%) were the highest, indicating that SDF in the mixed bacteria fermentation group had the best lipid-lowering effect. In conclusion, the structure and function of SDF from highland barley bran could be significantly improved by lactic acid bacteria fermentation, and the physical, structure and function of SDF in the highland barley bran treated with the mixed bacteria fermentation are better. This study layed a certain foundation for the development and application of highland barley bran.