Long-chain fatty acid esters produced by Sporidiobolus pararoseus or Rhodotorula mucilaginosa enhance the fat flavor of soy sauce fermented by defatted soybeans.

Two unique oleaginous strains, Sporidiobolus pararoseus and Rhodotorula mucilaginosa, were identified during soy sauce fermentation. Both strains demonstrated robust growth under extreme conditions (15 % NaCl, pH 5, 3 % ethanol). Lipidomics revealed 689 and 678 lipid species in S. pararoseus and R. mucilaginosa, with 671 shared components. Among the common components, Triglyceride (TG, 180 species), Diglyceride (DG, 72 species), and Ceramides (Cer, 52 species) were significantly enriched, directly participating in the biosynthesis of characteristic aroma substances by releasing fatty acids with chain lengths of C14-C18. GC-MS analysis showed 1.25- and 1.20-fold increases in long-chain fatty acid esters compared to traditional fermentation. These esters contributed to fat flavor formation and enrichment in defatted soybean sauce fermentation. The findings provide a theoretical basis for developing tailored strains to regulate lipid-derived aroma profiles in fermented soybean products.