Correlation of the bacterial communities with umami components, and chemical characteristics in Zhejiang xuecai and fermented brine.

Xuecai is a Chinese-fermented vegetable product that has attracted much attention because of its unique umami taste. However, investigations of the bacterial communities, umami components and chemical characteristics in xuecai and the brine have not yet been conducted. In this study, the bacterial communities and their correlations with the umami components and the chemical characteristics are investigated. The results showed that significantly higher contents of total protein, total acid, amino acid nitrogen, total sugar, titratable acidity, salt, amino acids and organic acids, as well as significantly lower nitrite concentrations were observed in the brine samples. The supervised pattern recognition method revealed that the xuecai and brine could be distinguished by these indicators. In addition, the xuecai and brine were both dominated by Lactobacillus, Halanaerobium and Halomonas. A correlation analysis showed that halophilic bacteria had a positive effect on the umami components and chemical characteristics of the xuecai and brine. However, lactic acid bacteria both showed a negative correlation with amino acids and most organic acids. Membrane transport, carbohydrate metabolism and amino acid metabolism were the most abundant pathways. These results enhance our understanding of the bacterial communities, as well as the umami components and chemical characteristics in Zhejiang xuecai and brine.