Influence of Inoculating Saccharomyces cerevisiae and Levilactobacillus brevis on the Quality of Fermented Large Yellow Croaker (Larimichthys crocea): Biogenic Amines, Volatile Components, and Microbial Communities Changes

As a representative of traditional Chinese fermented fish, fermented large yellow croaker (<i>Larimichthys crocea</i>) is characterized by its rich aroma, appealing color, distinctive flavor, and long shelf life. In this study, <i>Saccharomyces cerevisiae</i> (<i>S. cerevisiae</i>) and <i>Levilactobacillus brevis</i> (<i>L. brevis</i>) were inoculated to enhance fermentation, and their effects on biogenic amine (BA) formation, volatile flavor compounds (VFCs), and microbial community composition were investigated. Combined inoculation significantly reduced most BAs and nitrite levels, thereby improving the safety of fermented large yellow croaker. The <i>S. cerevisiae</i>-inoculated group exhibited higher contents of ester compounds such as 3-methylbutyl acetate, 2-methylpropyl acetate, and ethyl 2-methylbutanoate. <i>L. brevis</i> effectively suppressed spoilage and amine-producing bacteria, including <i>Aeromonas</i>, <i>Shewanella</i>, and <i>Morganella</i>. Pearson's correlation analysis revealed that <i>Levilactobacillus</i> was positively correlated with butyl 2-methylbutanoate, (Z)-4-heptenal, pentyl acetate, 2-ethyl-3-methylpyrazine, 3-methylbutyl acetate, 4-methyl-2-pentanone, 3-pentanone, and propanal, while <i>Saccharomyces</i> showed positive correlations with propionaldehyde, 1-penten-3-ol, 4-methyl-3-penten-2-one, (E)-2-pentenal, and 2-hexenal. In contrast, BAs were negatively correlated with <i>Levilactobacillus</i> and <i>Saccharomycopsis</i>, but positively correlated with <i>Aeromonas</i>, <i>Shewanella</i>, <i>Photobacterium</i>, <i>Vagococcus</i>, <i>Vibrio</i>, <i>Morganella</i>, <i>Lactococcus</i>, <i>Apiotrichum</i>, and <i>Cutaneotrichosporon</i>. Overall, these findings demonstrate that <i>L. brevis</i> and <i>S. cerevisiae</i> improve both the flavor and safety of fermented large yellow croaker. This study offers a theoretical basis for advancing industrial production of fermented fish products.