Metabolomic fingerprint changes during the alcoholic fermentation at industrial level of Muscat of Alexandria grape must

Abstract

Muscat of Alexandria is one of the oldest cultivars still existing, globally recognized for its distinctive aroma, and the primary grape variety cultivated in the Greek Island of Lemnos, yielding various white wines with designated origins. On the other hand, understating the changes occurring during alcoholic fermentation is of paramount importance in wine science and wine making, and untargeted metabolomics, which enable the registration of thousands of metabolites in a single analysis, could serve as a valuable tool for the comprehensive study of these changes.

The aim of this study was to track the metabolomic profile of Muscat of Alexandria grape must during the industrial-level alcoholic fermentation. For this purpose, numerous samples were collected from eleven tanks originating from three wineries on Lemnos Island across two vintages (2019 and 2020) and analysed using ultra-high pressure liquid chromatography coupled to time-of-flight mass spectrometry in both positive and negative electrospray ionization modes (UPLC-QTOF-MS). The data processing and analysis divided the annotated metabolites into different categories based on the behaviour. Between others, the tentative biomarkers included sugars, organics acids, vitamins, amino acids, peptides, flavonoids, nucleosides and terpene glycosides. Notably, small peptides exhibited analogous trends with amino acids, indicating rapid consumption similar to the amino acids. This peptides consumption potentially elucidated the observed proline increase, which is not preferrable by the yeasts. Additionally, some peptides exhibited increased concentrations towards the end of fermentation. Furthermore, the hydrolysis of terpenes and phenolic glycosidic bonds, alongside the release of nucleic acid building blocks into the must during fermentation, were highlighted. Overall, this comprehensive analysis enhances understanding of how alcoholic fermentation influences wine quality under realistic conditions.

References

[1] Marinaki, M.; Mouskeftara, T.; Arapitsas, P.; Zinoviadou, K. G.; Theodoridis, G. (2023) Molecules, 28 (12), 4653.

[2] Marinaki, M.; Sampsonidis, I.; Lioupi, A.; Arapitsas, P.; Thomaidis, N.; Zinoviadou, K.; Theodoridis, G. (2023) Talanta, 253, 123987.