Effects of salt concentration on the quality of paocai, a fermented vegetable product from China

BACKGROUND: Paocai is a traditional Chinese fermented vegetable food. As the most important ingredient, salt has crucial effects on the bacterial community and volatile compounds of paocai. To demonstrate the effects of salt on the fermentation of paocai, the bacterial composition and volatile compounds were investigated using high-throughput sequencing and gas chromatography-mass spectrometry (GC-MS). RESULTS: The salt had no significant effects on the bacterial community at the phylum level. Proteobacteria and Bacteroidetes gradually decreased during the fermentation, and Firmicutes gradually increased as the dominant bacteria in the late stage of fermentation. At the genus level, Lactobacillus and Lactococcus gradually increased in relative abundance during the fermentation and became the dominant bacteria in paocai. High salt levels can contribute to the growth of Lactobacillus, which became the dominant genus in paocai. The salt concentration affected the profiles of volatile compounds in paocai after fermentation. A total of 42 volatile components were detected by GC-MS, among which phenols, aldehydes, and nitriles were the main ones. A high salt concentration will increase the volatile compound content, mainly aldehydes and alcohols, and improve the flavor of paocai. At the same time, the electronic tongue analysis also showed that a high salt concentration made a major contribution to the flavor of paocai. CONCLUSIONS: These data are helpful to elucidate the effects of salt on the quality of paocai and contribute to improving the quality and reducing the use of salt. © 2021 Society of Chemical Industry.