Study on the factors affecting the sauce-flavor compounds of soybean paste in fermentation

Soybean paste is widely used as a seasoning for authentic Asian cuisine due to its rich and savory sauce flavor. However, the primary components of the soybean paste sauce-flavor compounds and the fermentation regulation mechanisms are still unclear. Therefore, the present study sought to systematically explore the factors affecting the sauce flavor in terms of substrate, external microorganisms, brine concentration, and the alteration in flavor composition and its regulatory mechanisms. The results of the raw material ratios showed that an appropriate increase in the proportion of soybeans (6:4) could significantly enhance the concentration of amino acid metabolites, such as 2-methylbutanal, 3-methylbutanal, and 2-phenylethanal. Delayed addition to Tetragenococcus halophilic significantly enhanced 2-butylfuran, 2-pentylfuran, trans-2-(2-pentenyl) furan, and sauce-flavor perception in soybean paste by modulating the total acid. A suitable brine concentration (10%) could adjust the fermentation process and facilitate the formation of benzaldehyde, 2-ethylfuran, 2-butylfuran, 2-pentylfuran, and other sauce-flavor compounds. Meanwhile, combined results of sensory evaluation and GC-MS analysis demonstrated that the primary components of the sauce-flavor compounds in soybean paste consisted of furans (furfural, 2-methylfuran, 2,5-dimethylfuran, 2-ethylfuran, 2-butylfuran, 2-pentylfuran) and pyrazine (2,6-dimethylpyrazine, 3-ethyl-2,5-dimethylpyrazine). Overall, these results provide a theoretical basis for the targeted enhancement of the sauce-flavor of soybean paste and insights into the industrial production of high-quality soybean paste.