Evaluation of bacterial contribution in traditional fermented food of grasshopper sub shrimp paste1

The presence of biogenic amines (BAs) in fermented foods represent a health risk for consumers, and thus studying the mechanism by which these BAs are accumulated could provide an important mean to control their content in fermented foods. In this study, we evaluated the BAs profiles of grasshopper sub shrimp paste samples taken at seven different regions around the Bohai Sea. At the same time, we also determined the physicochemical indexes and microbial counts of samples. In addition to BAs, microbial diversity is also an important factor affecting food quality and safety. In grasshopper sub shrimp paste, Tetragenococcus, Lactobacillus, Aspergillus and unclassified_k_Fungi were identified as the predominant genera. Halophilic bacteria may be the main reason for BAs-production in the shrimp paste. A total of 442 strains of halophilic bacteria were identified and the five most abundant genera were Bacillus, Staphylococcus, Tetragenococcus, Virgibacillus and Oceanobacillus. The characteristics associated with BAs-production in the halophilic bacteria were studied, and different strains were found to produce different types and concentrations of BAs, with most of the species (95.10%) having the ability to produce BAs, though such ability appeared to varies greatly. Among the BA-producing halophilic bacteria, thirty strains were considered high producers, and this could be the main reasons for the production of BAs of grasshopper sub shrimp paste samples in seven regions (Panjin, Rongcheng, Shouguang, Dalian, Tangshan, Qinhuangdao and Yantai). The species that produced very low of BAs (< 10 mg/kg) were also screened for the experiments of amine oxidase. The present study not only helped to explain the mechanism by which BAs are accumulated in grasshopper sub shrimp paste, but would also develop the candidates for potential BAs control in fermented aquatic products.1