Effect of Protease Preparation on Physicochemical Properties and Microbiota of Shrimp Paste during Fermentation

In order to improve the production process of shrimp paste, the effect of a commercial protease preparation on the physicochemical properties and microbial community of shrimp paste during fermentation was systematically studied in this work. The pH, amino acid nitrogen (AAN), malondialdehyde (MDA), total volatile basic nitrogen (TVB-N) and biogenic amine of shrimp paste were measured. The composition of the bacterial community was analyzed by high-throughput sequencing technology. The correlation between the bacterial community and physicochemical properties during shrimp paste fermentation was analyzed by Spearman's test. The results showed that the contents of AAN and TVB-N in shrimp paste with the addition of the protease preparation increased more significantly during fermentation compared with the blank control group, shortening the fermentation time but simultaneously leading to a decline in the quality of shrimp paste.However, its addition had no apparent effect on the biogenic amine content. A total of 313 864 valid sequences clustered into 1 279 operational taxonomic units (OTUs) were obtained from shrimp paste samples. The addition of the enzyme preparation significantly affected the bacterial community composition and reduced the bacterial richness. At the genus level, Flavobacterium was the dominant bacterium in the control group, while Bacillus became dominant upon the addition of the enzyme preparation, together with increased relative abundance of Bacillus and reduced relative abundance of Lactococcus.The dominant flora was Bacillus, Flavobacterium and Lactococcus, which affected the quality and physicochemical properties of shrimp paste. In conclusion, the addition of the protease preparation had an important effect on the bacterial community composition, MDA, TVB-N and AAN contents in shrimp paste during fermentation, which would provide a theoretical basis for improving the production process of shrimp paste. © 2021, China Food Publishing Company. All right reserved.