Abstract: In order to explore the differences in the metabolite profiles of industrially long-term fermented kohlrabi with different fermentation periods and the major metabolic pathways involved, the metabolite profiles of kohlrabi fermented for 0, 5 and 10 years were analyzed and compared by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) combined with multivariate statistical analysis. The results showed that a total of 53, 113 and 174 differential metabolites were identified in years 0 versus 5, 5 versus 10, and 0 versus 10 of fermentation, respectively (variable importance in the projection (VIP) > 1.3, P < 0.05), including organic acids, amino acids, nucleic acids and their derivatives. Nineteen differential metabolites were common to the three fermentation time points, including L-phenylalanine, and β-D-fructose-6-phosphate. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the differential metabolites showed that phenylalanine metabolism, the pentose phosphate pathway, and the fructose and mannose metabolic pathways were the most significantly correlated with the major differential metabolites. The present study provides a theoretical basis for targeted regulation of the biosynthesis of the characteristic metabolites in fermented kohlrabi.

Key words: kohlrabi; long-term fermentation; metabolomics; liquid chromatography-tandem mass spectrometry; differential metabolites