Metabolomic differentiation of industrial baker's yeasts reveals yeast product formulation-associated metabolic and flavor signatures during dough fermentation and bread baking

초록

Saccharomyces cerevisiae (baker's yeast) plays a pivotal role in breadmaking by driving dough leavening and generating key flavor and aroma compounds. However, the metabolic mechanisms by which yeast product formulation type-fresh versus active dry-is associated fermentation behavior and bread quality remain insufficiently understood. In this study, six commercial S. cerevisiae strains were systematically characterized through enzymatic profiling, genetic identification, and integrated metabolomic analysis to elucidate product-associated metabolic differences. The VITEK 2 system revealed distinct enzymatic phenotypes, notably the alpha-glucosidase activity unique to the L'hirondelle LHIS White (Lesaffre; ADLL) strain, which corresponded with enhanced maltose utilization. Internal transcribed spacer sequencing confirmed that even yeasts from the same manufacturer represent genetically distinct strains, reflecting divergent genetic backgrounds across commercial products. Non-volatile metabolomic profiling identified 94 metabolites, with fresh yeast accumulating protective amino acids-including gamma-aminobutyric acid, cysteine, and threonine-whereas active dry yeast strains showed markedly lower levels of these compounds, reflecting stress-adaptive regulation (p-value <0.05). In contrast, volatile metabolite analysis by solid-phase microextraction-gas chromatography/mass spectrometry demonstrated yeast product formulation-associated aroma profiles: fresh yeast product formulation predominantly produced fusel alcohols and aldehydes such as 3-methyl-1-butanol and nonanal through amino acid catabolism, whereas active dry yeast favored fatty acid esterification, generating complex fruity esters such as phenylethyl acetate and ethyl decanoate. These divergent metabolic patterns persisted after baking, resulting in stable yeast product formulation-associated aroma signatures. Collectively, this integrative metabolomic and biochemical investigation provides mechanistic insight into how yeast product formulation type and genetic background collectively influences fermentation metabolism and sensory properties, offering a scientific foundation for targeted strain selection and yeast product formulation optimization in industrial bread production.

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