Co-culturing Limosilactobacillus fermentum and Pichia fermentans to ferment soybean protein hydrolysates: An effective flavor enhancement strategy

This study explored the effects of varying fermentation durations on the flavor profiles of fermented soybean protein hydrolysates using Limosilactobacillus fermentum and Pichia fermentans and investigated the correlation between flavor-active compounds and sensory attributes. Fermentation significantly enhanced umami and saltiness while reducing bitterness. As fermentation progressed, large peptides degraded, releasing free amino acids (FAAs) that increased umami and sweetness, along with a rise in proportion of potential umami peptides. Organic acid analysis revealed lactic, acetic, and malic acids, as major contributors to sourness and sweetness. Among 125 volatile flavor compounds (VFCs), 24 key VFCs enhanced flavor quality and reduced beany odors. Notably，fermentation for 24–30 h produced the most balanced flavor profiles. Partial least squares regression (PLSR) analyses revealed strong associations between small peptides, FAAs, VFCs, and sensory attributes, identified 4 FAAs and 8 VFCs as key contributors to flavor differentiation, providing insights into improving soybean-based product flavor quality.