From detail to diversity: capturing the chemical signature of non-Saccharomyces yeasts in white wine through GC×GC/TOF-MS metabolomics and complementary analytical approaches

To gain a broad understanding of yeast species' effects, Malvazija istarska wines produced by sequential inoculation with five non-Saccharomyces starters and monoculture fermentation with a Saccharomyces cerevisiae×S. paradoxus hybrid and a S. cerevisiae control were thoroughly analyzed. Two-dimensional gas chromatography/mass spectrometry, alongside conventional GC, enabled the identification of 399 volatile compounds and revealed many yeast-specific effects. Non-Saccharomyces starters generally decreased the concentrations of acetaldehyde, 2-phenylethanol, fatty acids, and volatile phenols, while increasing the concentrations of isobutanol, its esters, and isoamyl acetate. Torulaspora delbrueckii had the most pronounced impact, with higher concentrations of short-chain ethyl esters and acetates, and lower levels of acetaldehyde, medium-chain acids, and their ethyl esters. The effects on terpenoids, norisoprenoids, thiols, C6-alcohols, ketones, lactones, and furanoids varied. Multivariate analysis revealed numerous yeast-specific volatile markers. Non-Saccharomyces yeasts preserved more hydroxycinnamic acids. Overall, the results obtained provided an in-depth insight into the yeast-driven modulation of white wine chemical composition