Species synergy effects on milky aroma are conditioned by moisture-gradient driven pore evolution of protein-fat networks in fermented sausages.

Abstract

This study investigates the role of protein-fat networks in milky aroma formation in fermented sausages. Three species compositions, CK (uninoculated control), NJM (Lactobacillus paracasei YL-1, Staphylococcus equorum NY-3, Staphylococcus xylosus E-2), and QB (NJM plus Debaryomyces hansenii F4), were used under controlled temperature and humidity to create moisture gradients. The QB group had the highest aroma compound levels and strongest milky aroma (7.86/9). A significant increase in key milky aroma compounds, 3-hydroxy-2-butanone and 2,3-butanediol, was observed between days 21 and 28 (P < 0.05). These compounds were associated with the transition of protein-fat networks from sol to gel structure, and converting free water into bound water. The resulting conditions optimized water activity (aw) for aroma-producing Staphylococcus, while also supporting the synergistic activity of D. hansenii and L. paracasei in aroma accumulation. In the early stages, both pH and moisture gradients influenced the pore structure, with moisture gradients dominating later.