Synergistic improvement of hydrolyzed vegetable protein quality and flavor enhancement through multi-microbial fermentation and acid hydrolysis

Three optimized strains SA ( Bacillus subtilis ), CM17 ( Cordyceps militaris ), and MI ( Aspergillus oryzae ) were empioyed to prepare hydrolyzed vegetable protein (HVP) seasoning and fermentation conditions were optimized to maximize yield. The optimal fermentation conditions were achieved with 15 % soybean meal, 8 % wheat bran, and 5 % inoculum of the blended strains, and when combined with acid hydrolysis, the degree of hydrolysis of HVP can reach 68.88 %, and the amino acid nitrogen content can reach 1.26 g/100 g. The amino acid profiles of HVP prepared through acid hydrolysis (HVP-S), optimized fermentation (HVP-RSM), and a combination of both (HVP-O) were compared. The taste and flavor differences were evaluated using electronic nose and tongue technologies, as well as gas chromatography-mass spectrometry (GC-MS). The analysis revealed that HVP-O exhibited the highest free amino acid content, with glutamic acid and aspartic acid levels significantly elevated compared to other groups. Flavor analysis indicated that 3-methyl-1-butanol and 1-octen-3-ol in HVP-O had higher relative odor activity values (ROAV), contributing to the characteristic alcoholic and mushroom aromas. The correlation analysis revealed that the key process factors significantly influencing flavor and free amino acids were the involvement of Aspergillus oryzae in fermentation and the application of acid hydrolysis. • Novel proteolytic strains: SA ( B. subtilis ), CM17 ( C. militaris ), MI ( A. oryzae ). • HVP-O (acid-assisted fermentation) DH 68.88 %, amino acid nitrogen 1.26 g/100g. • HVP-O: Highest free amino acids (GLU, ASP), unique 2,3-butanedione. • A. oryzae fermentation and acid hydrolysis drive flavor/amino acid synergy.