Exploring the origin of off-flavor compounds in bacterial-type shuidouchi using molecular sensory science techniques

Bacterial-type shuidouchi (SDC) produces undesirable off-flavors that impact its quality and acceptance. This study employed molecular sensory science to investigate the origin of off-flavor compounds in a mixed SDC model (mSDC). Gas chromatography-mass spectrometry (GC - MS) analysis identified 100 odor-active compounds. By integrating odor activity value (OAV) calculations with GC - olfactometry (GC - O), four off-flavor compounds emerged as critical markers: dimethyl disulfide, dimethyl trisulfide, isovaleric acid, and 2-methylbutyric acid. Molecular docking confirmed their binding to human olfactory receptors, highlighting OR2T4, OR2T5, OR10H3, OR2T2, and OR10H1 as key targets. Aroma recombination and omission experiments show dimethyl disulfide and dimethyl trisulfide had the greatest contribution to off-flavors. Perception interaction experiments revealed interactions between the four off-flavor compounds. This study is the first to integrate molecular sensory science, molecular docking techniques, and sensory interaction analysis for the systematic characterization of off-flavor compounds in bacterial-type SDC, providing theoretical support for flavor regulation of traditional fermented soybean products.