The impact of PAHs on the taste substances of Chlamys farreri during the reproductive period: Changes in flavor characteristics and metabolic mechanisms

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in marine environments, posing significant threats to the safety of seafood derived from marine sources. This study explores the alterations in flavor characteristics of the scallop Chlamys farreri during the reproductive period under gradient stress of the representative PAH benzo[a]pyrene (B[a]P). The contents of primary taste substances—amino acids, nucleotides, and organic acids—were quantified, along with changes in taste activity values (TAVs) and equivalent umami concentrations (EUCs). Additionally, the mechanisms underlying the metabolic changes of taste substances in scallops under B[a]P stress were deciphered at the genetic level. The findings indicate that high concentrations of B[a]P significantly reduced the content of umami amino acids in scallops, resulting in a significant decline in the corresponding TAVs and EUCs, while no significant changes were observed in the contents of organic acids and nucleotides. Transcriptomic analysis identified key pathways associated with the metabolism of taste substances, and the expression levels of related genes were determined. Genes involved in the synthesis of glutamate, glycine, alanine, and arginine were generally repressed, with the degree of repression intensifying with the extension of time and the increase in B[a]P concentration. The key gene ABAT in the succinate synthesis process was induced, while no significant changes were observed in other genes. This study investigates the potential threat of marine PAHs contamination to the quality of seafood products derived from seawater and provides new insights into the molecular mechanisms by which pollutants alter the taste of aquatic products.