Effect of salt concentration on microbial communities, physicochemical properties and metabolite profile during spontaneous fermentation of Chinese northeast sauerkraut

AIM: The aim of this study was to study the effects of salt concentrations on the microbial communities, physicochemical properties, metabolome profiles and sensory characteristics during the fermentation of traditional northeast sauerkraut. METHODS AND RESULTS: Northeast sauerkraut was spontaneously fermented under four salt concentrations (0·5, 1·5, 2·5 and 3·5%, w/w). The result of microbiological analysis showed that the population of lactic acid bacteria in 2·5%-salted sauerkraut was significantly higher than that in the other samples. Correspondingly, the speed of decrease in pH and accumulation of acids were the highest in 2·5%-salted sauerkraut. The glucose (analysed by HPLC) in 2·5%-salted sauerkraut was consumed more completely to produce higher levels of organic acids compared to those in the other samples. Principle component analysis showed clear differences in the metabolites of sauerkraut according to different salt concentrations. A higher level of volatiles (detected by HS-SPME/GC-MS) was identified in 2·5%-salted sauerkraut, and sensory evaluation demonstrated that 2·5%-salted sauerkraut had the best sensory characteristics. CONCLUSION: The best quality of sauerkraut was obtained from fermented under 2·5% salt concentration. SIGNIFICANCE AND IMPACT OF THE STUDY: This study facilitated the understanding of the effects of salt on the sauerkraut fermentation and may be useful for developing the quality of sauerkraut.