Effect of different lactic acid bacteria on nitrite degradation, volatile profiles, and sensory quality in Chinese traditional paocai

Paocai is one of the most popular traditional fermented products in China. Different lactic acid bacteria (LAB) have an important influence on the microbial changes, the dynamic changes of metabolites, and the sensory qualities of paocai. In this study, five different paocai groups were designed which were fermented by Lactobacillus plantarum DMDL 9010 (LP), Lactobacillus brevis GIM 1.773 (LB), Leuconostoc mesenteroides GIM 1.774 (LM), mixed three kinds of LAB (LP + LB + LM), pasteurization (PST) and natural fermentation (NF) without LAB. The nitrite, nitrate, pH, titratable acidity, viable count (LAB and yeast) and metabolites (organic acids, sugars and volatile substances) of these paocai groups were measured. Compared with each single bacterial fermentation (LP, LB and LM), NF and PST, the mixed three kinds of LAB (LP + LB + LM) had a lower nitrite peak, which could be attributed to the significant accumulation of organic acids, and positively affected sensory quality of paocai. Flavor substances produced in paocai samples confirmed as alcohols, ketones and olefins. Sensory evaluation showed that multi-bacteria mixed fermentation of paocai had a better flavor than that of NF, PST and single bacterial fermentation. Therefore, the use of multiple LAB as starter cultures contributes to enhance paocai qualities and control the levels of nitrite.