Abstract:Seventy-four strains of lactic acid bacteria were screened from traditional fermented foods and healthy human intestines through isolation and purification, morphological observation, and 16S rDNA identification. Five strains of these bacteria (Lactiplantibacillus plantarum Q2.3, L. fermentum LF3.2, L. pentosus Q1.4, L. plantarum G1.4, L. plantarum G1.3) with optimal gastrointestinal fluid tolerance, acid production capacity, and proliferation capacity were identified. Effectiveness of the five bacterial strains in the fermentation of soy milk, peanut milk, and chickpea milk, was examined. L. fermentum LF3.2 produced the most acid in the three kinds of bean milk after 24 h of fermentation, with minimum pH values lower than 4.5 for the fermented soy milk and peanut milk. At this point, the viable bacteria count in all three fermented bean milks exceeded 8 log CFU/mL. L. fermentum LF3.2 and L. plantarum G1.3 proliferated most in soy milk and peanut milk, while L. fermentum LF3.2 and L. plantarum G1.4 proliferated most in chickpea milk. The antioxidant activities of all three bean milks were significantly increased after 24 h of fermentation by L. fermentum LF3.2 and L. plantarum G1.3. Scavenging of α, α-Diphenyl-β-Picrylhydrazyl free radicals (DPPH.) and hydrogen radicals (OH.) were 23.34% and 23.64% higher, respectively, in fermented soy milk than in unfermented soy milk. L. fermentum LF3.2 increased the DPPH. clearance rate and L. plantarum G1.3 increased the OH. clearance rate of all three bean milks. These findings serve as guidance for the development of functional fermented bean milk, and lay a theoretical foundation for the application of lactic acid bacteria in plant-based fermented foods.
