Differences in taste and material basis of soybean and defatted soybean fermented soy sauces and influence factors

Soybean and defatted soybean have been widely used as protein materials in soy sauce fermentation. Defatted soybean is welcomed by the industry for lower costs and higher level of protein. It has been revealed that defatted soybean fermented soy sauce (SS-DS) has a less appealing flavor than whole soybean fermented soy sauce (SS-HS). But the taste differences in molecular basis between the two remain unexplored. In this study, quantitative descriptive analysis (QDA) demonstrated SS-HS had a more harmonious and palatable taste, while SS-DS exhibit a more bitter taste. 9 organic acids, 15 sugars and sugar alcohols, 17 amino acids, 31 peptides and 12 Amadori compounds in soy sauce were detected by gas chromatography-mass spectrometer combined with derivatization (Der-GC-MS) and ultra-performance liquid chromatography quadrupole time-of flight mass spectrometry (UPLC-Q-TOF-MS). Sixteen compounds with taste active value (TAV) higher than 1 were identified as key substances. Further, it was found that lipid composition played an important role in taste difference between SS-HS and SS-DS, especially phospholipids. This paper determined the taste difference basis between SS-HS and SS-DS, and clarified the role of lipids in formation of these differences, which provided a theoretical reference for the flavor regulation in soy sauce industry.