Screening and Application of Dominant Lactic Acid Bacteria and Yeasts in Rice Sour Soup from Miao

Objective: To obtain the starter culture suitable for rice sour soup fermentation, and realize the standard produc-tion of traditional rice sour soup. Methods: The excellent strains of lactic acid bacteria were screened by calcium-dissolving circle method combined with total acid yield and the tolerance experiments of acid and bile salt; The experiment of glycosidase activity was used to screen the excellent strains of yeast. The strains were identified by physiological and biochemical experiments, 16S rDNA and ITS sequence; The compounded two excellent fermentation strains were applied to rice sour soup, and their pH, total acid, total sugar, reducing sugar and sensory quality were analyzed. Results: The strain G1-3 with strong acid-producing ability was selected from 128 strains of lactic acid bacteria, which grew well in the environment of pH3.0 and 0.3% bovine bile salt. The strain G2-2 with strong glycosidase activity was screened from 20 yeasts. The strains G1-3 and G2-2 were identified as Lactobacillus paracasei and Torulaspora indica, respectively. Compared with natural fermentation, the total acid content of indica white sour soup fermented by two strains of bacteria increased by 5 times, while the total sugar and reducing sugar content decreased by 61.53% and 81.02%, respectively; The total acid content in glutinous rice sour soup increased by 18 times, while the content of total sugar and reducing sugar decreased by 68.86% and 86.99%, respectively. Also, the sensory quality of white sour soup fermented by two strains of bacteria was better than that of natural fermentation. Conclusion: The white sour soup fermented by compound starter of G1-3 and G2-2 has excellent quality, which is expected to be applied to the fermentation production of white sour soup.