Unravelling the Dynamics of γ-Glutamyl Dipeptides, Microbial Composition, and Kokumi Attributes during Fermentation of Traditional Shrimp Paste

This study aimed to investigate variations in γ-glutamyl dipeptides in traditional shrimp paste prepared from shrimp heads with 20% (S20), 25% (S25), and 30% (S30) (w/w) NaCl. Microbial community composition, sensory characteristics, free amino acids and γ-glutamyl dipeptides were analyzed. Results showed that a total of 19 γ-glutamyl dipeptides (excluding γ-EC) were detected, with their concentrations generally increasing over the course of fermentation. On day 28, S20 exhibited the highest scores in all kokumi attributes, which aligns with its highest total concentration of γ-glutamyl dipeptides (22.1 ± 0.6 μmol/g) compared to S25 (20.6 ± 0.6 μmol/g) and S30 (18.1 ± 0.3 μmol/g). Moreover, the formation of γ-glutamyl dipeptides in S20 was primarily associated with Salimicrobium and Alkalibacillus, whereas in S25 and S30 it was correlated with unclassified_f_Rhodobacteraceae, Shewanella, Vibrio, and Altererythrobacter . These findings offer useful insights into strategies for improving the taste quality of shrimp paste.