Variations in the physicochemical properties and bacterial community composition during fermentation of low-salt shrimp paste

The main purpose of the present study was to investigate the influence of two fermentation temperatures (10 °C and 20 °C) on the physicochemical properties and bacterial community composition of the low-salt shrimp paste. The physicochemical properties pH values, total volatile basic nitrogen (TVBN), amino acid nitrogen (AAN) and biogenic amines (BAs) of low-salt shrimp paste were analyzed and compared. The bacterial community composition was analyzed by high-throughput sequencing technology. Results indicate that the pH value fluctuated between 8.50 and 7.95, and the AAN, TVBN and total BAs levels of low-salt shrimp paste increased gradually after fermentation started, but the AAN content fluctuated steadily after 12 w. The contents of TVBN and total BAs in shrimp paste fermented at 10 °C were lower than those at 20 °C. Thus, the appropriate fermentation temperature and period were 10 °C and 12 w, respectively. Carnobacteriaceae and Staphylococaceae were the predominant family for the fermented shrimp paste. At the genus level, Alkalibacterium was predominantly present at 8 wk (96.36%), while Staphylococcus became the predominant one at 20 wk (58.71%). Correlation analysis shows that Alkalibacterium was positively associated with tyramine (R2 = 0.59), and Staphylococcus and Tetragenococcus were positively associated with AAN and TVBN. These findings are used to facilitate the quality control and improvement of low-salt shrimp paste production process in the future.