Effects of fermented anchovy sauce addition and thermal treatment on the microbial and metabolic profiles of kimchi

Fermented anchovy sauce is a key seasoning that contributes to both flavor development and microbial activity during fermentation. This study investigated the impact of fermented anchovy sauce and its thermal treatment on kimchi fermentation. Microbial profiling revealed early presence of Tetragenococcus muriaticus only in the untreated sauce group, while Latilactobacillus sakei dominated all groups by late fermentation. By week 6, both sauce-treated groups exhibited approximately 1.4-fold higher total nitrogen levels than the control, accompanied by a greater accumulation of amino acids throughout fermentation, reflecting enhanced protein release via microbial proteolysis. The heat-treated group also showed higher levels of functional metabolites such as 4-aminobutyric acid (GABA) and mannitol, along with more rapid depletion of fructose and sucrose, indicating accelerated fermentation. Heat treatment further enhances fermentation efficiency by promoting proteolysis, reducing microbial competition, and supporting LAB dominance. This study highlights the potential of ingredient-level processing to control fermentation outcomes and enhance functional metabolite production in kimchi. • The addition of fermented anchovy sauce significantly alters microbial and metabolic profiles of kimchi. • Untreated sauce introduces Tetragenococcus muriaticus , impacting early microbial diversity. • Sauce addition promotes proteolysis, enriching the amino acid pool in kimchi • Kimchi with heat-treated sauce exhibits higher levels of beneficial metabolites including GABA and mannitol.