Metabolomic Analysis of Low-salt Shrimp Paste during Fermentation at Low Temperature Based on Gas Chromatography-Mass Spectrometry

The metabolite profile of low-salt shrimp paste during low-temperature fermentation was investigated by metabolomics based on gas chromatography-mass spectrometry (GC-MS), and the differential metabolites were selected by multivariate statistical analysis combined with t-test and variable importance in projection (VIP) analysis. The results showed that the orthogonal partial least squares discriminant analysis (OPLS-DA) model clearly discriminated the metabolite profiles of shrimp paste samples fermented at 10 (low temperature) and 20 (control) ℃. A total of 44 metabolites were identified in the two samples, including 16 amino acids, 6 fatty acids, 2 amines, 8 organic acids, 3 alcohols, 3 nucleotides and 6 other compounds. By considering P < 0.05 and VIP > 1, 30 differential metabolites were obtained, including 7 amino acids, 2 esters, 2 purines, 8 organic acids, 2 alcohols and 9 other metabolites. The levels of L-serine, L-threonine, xanthine, hypoxanthine and L-glutamine in the low-temperature group were significantly higher than those in the control group, while the levels of nerazine acetate, zeaxanthin and melatonin were significantly lower (P < 0.01). These results provide a theoretical basis for further improving the production process of low-salt shrimp paste.