Abstract: A total of 14 yeast strains were isolated from high-salt liquid-state moromi and identified into four species. Representative strains were selected for physiological and biochemical identification and evaluation of growth characteristics. Moreover, these strains were individually used to ferment soy sauce to explore their effects on flavor soy sauce by gas chromatography-mass spectrometry (GC-MS) detection and sensory evaluation. The results showed that Rhodotorula mucilaginosa and Candida metapsilosis, potential flavor-producing strains, could improve the flavor of soy sauce by producing more 2-phenethyl acetate, 3-methylthio-1-propanol and 2,6-dimethylpyrazine. However, Millerozyma farinose and C. parapsilosis had negative impacts on soy sauce flavor. Notably, M. farinose, forming colonies with a dry and wrinkled surface, could obviously increase the contents of 2-octanone, 2-nonanone and 1,2,3-trimethoxybenzene to produce an intense off-flavor. The findings of this study are meaningful for guiding flavor regulation during soy sauce fermentation.

Key words: soy sauce; yeast; flavor regulation; sensory analysis; gas chromatography-mass spectrometry