Untargeted metabolomics reveals key biochemical shifts during industrial Muscat of Alexandria alcoholic fermentation

Alcoholic fermentation is a complex biochemical process that profoundly impacts wine quality. Generally, most metabolomics studies focus on controlled laboratory-scale fermentations, and industrial conditions are very rarely investigated. This study addresses this gap by elucidating the metabolomic fingerprint changes of Muscat of Alexandria grape must during industrial-scale alcoholic fermentation, by applying a Mass Spectrometry-based untargeted metabolomics workflow. The results revealed that small peptides exhibited analogous trends to amino acids, since the concentration of some peptides decreased rapidly at the early stages of the fermentation, explaining the increase of the not preferred by yeasts proline, while other peptides accumulated towards fermentation's end. Additionally, terpenes and phenolics glycosidic bonds underwent hydrolysis, and nucleic acid building blocks were released into the must during fermentation. These metabolomic transformations may shape wine's longevity, identity and sensory profile, and therefore the outputs of this work are important in wine science and winemaking.