The bacterial diversity of sun-dried spanish mackerel in Dalian and application of Lactobacillus plantarum X23 as a bio-preservative.

Abstract

Sun-dried spanish mackerel is a common food in Dalian and made by adding salt and sun drying, which has special physical, chemical and microbiological properties. In this study, the physicochemical properties and microbial composition of the commercial available sun-dried spanish mackerel in Dalian were assessed, and some Lactobacillus strains were screened as bio-preservative for sun-dried spanish mackerel preparation. The results showed that the TVBN content in the traditional sun-dried spanish mackerel samples from Dalian was within 30 mg/100g, the histamine content was 7-17 mg/kg, and the dominant bacteria at the genus level were Lactobacillus , Psychrobacter and Ralstonia . A strain with bio-preservative potential was isolated from sun-dried spanish mackerel sample, identified as L. plantarum species by 16S rDNA sequencing, and assigned as L. plantarum X23. Fresh spanish mackerel flesh was treated with 16% brine and L. plantarum X23 at a dose of 10 7 CFU/mL, and then sun-dried. The sun-dried spanish mackerel flesh treated with 16% brine and L. plantarum X23 showed the decreased histamine and acid value, the increased free amino acids contents, and a higher sensory score, compared with the sun-dried spanish mackerel without L. plantarum X23 treatment. In conclusion, the sun-dried spanish mackerel purchased from the supermarkets in Dalian were edible safe, and L. plantarum X23 can significantly reduce the content of histamine and putrescine in the self-made low-salt sun-dried spanish mackerel, and has the potential to be as bio-preservative for sun-dried spanish mackerel preparation.