Production of biogenic amines and changes in the microbiome composition of dry-cured fish during dynamic storage up to the end of the shelf life

The aim of this study was to quantify and identify biogenic amines in vacuum packed dry-cured salmon, swordfish and tuna, stored under dynamic abuse temperature conditions during their shelf life. The same samples were also submitted to shotgun metagenomic sequencing to characterize their microbiome in terms of taxonomic groups and functional genes linked to biogenic amines production. In tuna and swordfish, the biogenic amines were always below the quantification limit. In salmon, cadaverine was 6.98 mg/kg at T0 and increased up to 535.69 mg/kg. Histamine, tyramine and putrescine were detected from day 32–61. The salmon microbiome was mostly represented by Photobacterium up to 19 days and then replaced by Latilactobacillus. Both genera included species, such as Photobacterium phosphoreum and Latilactobacillus curvatus, producing biogenic amines. The tuna microbiome was stable over time, while in swordfish Staphylococcus increased from day 32, becoming the most represented genus at the end of the shelf life. The functional genes associated with biogenic amines metabolism were more abundant in salmon than in tuna and swordfish, thus reflecting their biogenic profile. The results of this study highlight the importance of preventing the presence of biogenic amines in raw fish before to the dry-curing process, in order to avoid their accumulation during shelf life. Moreover, they may inform risk assessments and support the development of comprehensive regulatory standards for biogenic amines in dry-cured fish products.