Effect of inoculating lactic acid bacteria starter cultures on the nitrite concentration of fermenting Chinese paocai

Lactic acid bacteria (LAB) isolated from Chinese paocai (a type of mildly salted and lactic acid fermented vegetable) were studied for their ability to deplete nitrite during fermentation. Lactobacillus pentosus, Lb. plantarum, Leuconostoc mesenteroides, Lb. brevis, Lb. lactis, Lb. fermentum depleted 99.6%, 99.3%, 99.2%, 97.0%, 98.5% and 98.8% of the initial nitrite present in de Man, Rogosa and Sharpe (MRS) broth, respectively. Two of the LAB strains, namely, Lb. pentosus and Leu. mesenteroides were then used as starter cultures for paocai fermentation. During spontaneous paocai fermentation, nitrite content of cabbage rose, reached the nitrite peak and decreased thereafter, while only small fluctuations in nitrite concentration were observed for cabbages inoculated with starter cultures of Lb. pentosus and Leu. mesenteroides. At the same time, the numbers of some nitrate reducing bacteria, such as Enterobacteria, of paocai inoculated with starter cultures were significantly lower than those in spontaneous fermentations. Hence, the abilities of LAB to deplete nitrite and to inhibit the growth of nitrate reducing bacteria could be the reasons that limit the formation of nitrite during paocai fermentation.