Microbial Community Succession and Quality Change of Commercial Low-Salt Shrimp Paste during Fermentation

In order to improve the fermentation process of the emerging commercial low-salt shrimp paste, this study systematically analyzed the changes in the major quality indicators during the fermentation process. High-throughput sequencing technology was used to analyze the microbial community diversity and composition. The results showed that during the fermentation of shrimp paste, the pH, malondialdehyde (MDA) content, total volatile basic nitrogen (TVBN) content, amino acid nitrogen content, moisture content, salt content and biogenic amine content fluctuated in the range of 7.19–6.90, 3.09–5.56 mg/kg, 44.81–175.05 mg/100 g, 1.42–1.63 g/100 g, 59.19%–62.40%, 11.02%–12.04% and 0–113.29 mg/kg, respectively. The MDA content increased and then subsequently decreased. The contents of amino acid nitrogen, TVBN and biogenic amines all showed an increasing trend. At the middle and late stages of fermentation, the bacterial diversity indexes decreased significantly, and the fungal diversity indexes decreased slowly. At the early stage of fermentation (0–7 days), Streptococcus and Lactobacillus were the dominant bacterial genera. During the middle and late periods (34–145 days), Tetragenococcus was the dominant bacterial genus and was differential between the three stages of fermentation. Trichosporon was the dominant fungal genus at the early stage of fermentation. At the middle stage, Candida and Alternaria became the dominant genera. At the late stage, Candida became the dominant genus, and no significantly differential fungal genera were found between the three fermentation stages. The Spearman correlation heat map showed that compared with the fungus genera, the bacterial genera had a higher correlation with the physiochemical indicators, indicating that the bacterial community was dominant in the fermentation process. Tetragenococcus was positively correlated with the TVBN, amino acid nitrogen, and MDA contents; Streptococcus was significantly negatively correlated with the content of biogenic amines. Starting from the 64^th day, the quality indicators and microbial community of the shrimp paste remained basically stable, suggesting that shortening the fermentation time can be considered as an option to improve the fermentation process. These results provide a theoretical basis for improving the fermentation process of low-salt shrimp paste.