Screening A Combination of Lactic Acid Bacteria and Yeast and Application in Traditional Pickle

In order to explore the fermentation performance of lactic acid bacteria and yeast with different species relationships in the process of pickle fermentation, a pair of lactic acid bacteria and yeast with mutual promoting relationship from 8 strains of lactic acid bacteria and 5 strains of yeast from different food sources, were screened through the cross-culture of metabolites and co-culture methods, namely Lactobacillus plantarum J05 and Saccharomyces cerevisiae Y21. The co-culture relationship of this group of bacteria was analyzed by culture mode, inoculation sequence and inoculation ratio, then the pH, total acid, reducing sugar content and nitrite content were measured during the fermentation process. The results showed that the addition of the sterile metabolites of Saccharomyces cerevisiae Y21 in standing culture significantly promoted the growth of Lactobacillus plantarum J05 in the growing stage; the growth of both strains was promoted by inoculation of Saccharomyces cerevisiae Y21 followed by Lactobacillus plantarum J05 and the optimal inoculation ratio of two strains was 30:1 and 40:1. When the inoculation ratio of bacteria group was 30:1, at the stable stag of pickle fermentation, compared with natural fermentation group, single bacteria group and mutual inhibition group, the pH of mutual promotion group was 3.4~3.5, which was significantly lower than that of other groups (P<0.05). The highest total acid content was 1.25 mg/kg, which was significantly higher than that of other groups (P<0.01). The reducing sugar content was lower, maintaining about 0.10 g/100 g, and the peak nitrite content was 5.38 mg/kg, which was significantly lower than that in the other three groups except Saccharomyces cerevisiae Y21 group (P<0.01). In summary, this group of bacteria selected in this experiment would have strong fermentation ability, could shorten the fermentation period and reduce the nitrite content in pickles.