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Exploring the effects of milk-enriched walnut soy sauce: Insights from GC-IMS and metagenomics approach to flavor and microbial shifts

Year: 2025

Type: article

Abstract: This study investigates the impact of milk addition on the fermentation of walnut soy sauce, using Gas Chromatography-Ion Mobility Spectrometry (GC-IMS) and metagenomics to analyze flavor profiles and microbial dynamics. GC-IMS analysis showed significant increases in volatile compounds such as esters (ethyl acetate), aldehydes (hexanal), and alcohols (isoamyl alcohol), enhancing the aroma and taste. Metagenomic analysis revealed that milk increased microbial diversity, with Weissella and Lactobacillus dominating early fermentation. The milk-enriched soy sauce (SYM) exhibited higher amino acid nitrogen (2.67 g/L), and total nitrogen (7.18 g/L) compared to the control, indicating improved nutritional quality. Protease activity peaked at 2438.5 U/g for neutral protease, supporting efficient protein hydrolysis. Relative Odor Activity Value (ROAV) analysis identified 29 key flavor compounds, including 3-methyl butanol and ethyl 2-methyl butyrate, which contributed fruity and buttery notes to SYM. These results suggest that milk enhances microbial growth and improves both flavor and nutritional quality of walnut soy sauce. • Milk addition enhances microbial diversity and flavor complexity in fermentation. • Milk proteins enriched umami flavor by modulating microbial metabolic pathways. • GC-IMS revealed increased esters, aldehydes, and alcohols in milk-enriched soy sauce. • Nutrient-rich milk boosted fermentation, improving sensory and functional qualities. • This study introduces milk as a novel ingredient to elevate soy sauce fermentation.

Source: Food Chemistry X

DOI: 10.1016/j.fochx.2025.102364