Microbial dynamics and volatilome profiles during the fermentation of Chinese northeast sauerkraut by Leuconostoc mesenteroides ORC 2 and Lactobacillus plantarum HBUAS 51041 under different salt concentrations.

This study aimed to investigate the effects of salt concentration on the microbial community and flavor metabolites formed during northeast sauerkraut fermentation using a starter culture consisting of a combination Leuconostoc mesenteroides ORC 2 and Lactobacillus plantarum HBUAS 51041. The results revealed a correlation between microbiota and flavor metabolites, with the top 20 genera being identified using Illumina MiSeq. Lactobacillus and Leuconostoc were dominant genera throughout the fermentation process, and PCoA showed that the salt concentration had distinct impacts on the microbial community. The most abundant genus Lactobacillus (88.46%) was observed in the 0.5% salted sauerkraut at day 30. Forty-six flavor metabolites were identified by HS-SPME/GC-MS. The relative contents of esters, aldehydes and ketones showed the highest values in sauerkraut fermented with a 0.5% salt concentration. Sauerkraut fermented at 2.5 and 3.5% salt were characterized by higher relative contents of acids, alcohols, isothiocyanates and hydrocarbons. Spearman's rank correlation test results showed that Lactobacillus, Leuconostoc, Enterobacteriaceae, Pseudomonas, Staphylococcus and Bacillus were closely related to flavor metabolites. These results showed the effects of salt concentration on fermentation of northeast sauerkraut, revealing that sauerkraut fermented with 0.5% salt possessed a higher abundance of Lactobacillus and accumulated more flavor compounds (esters, aldehydes, ketones, nitriles and sulfides), providing a potential alternative approach to meet the preference of consumers for desirable aromatic quality. The results of this study may contribute to the industrial production of sauerkraut in Northeastern China.