1H-NMR Metabolomics as a Tool for Winemaking Monitoring

The chemical composition of wine is known to be influenced by multiple factors including some viticulture practices and winemaking processes. 1H-NMR metabolomics has been successfully applied to the study of wine authenticity. In the present study, 1H-NMR metabolomics in combination with multivariate analysis was applied to investigate the effects of grape maturity and enzyme and fining treatments on Cabernet Sauvignon wines. A total of forty wine metabolites were quantified. Three different stages of maturity were studied (under-maturity, maturity and over-maturity). Enzyme treatments were carried out using two pectolytic enzymes (E1 and E2). Finally, two proteinaceous fining treatments were compared (vegetable protein, fining F1; pea protein and PVPP, fining F2). The results show a clear difference between the three stages of maturity, with an impact on different classes of metabolites including amino acids, organic acids, sugars, phenolic compounds, alcohols and esters. A clear separation between enzymes E1 and E2 was observed. Both fining agents had a significant effect on metabolite concentrations. The results demonstrate that 1H-NMR metabolomics provides a fast and robust approach to study the effect of winemaking processes on wine metabolites. These results support the interest to pursue the development of 1H-NMR metabolomics to investigate the effects of winemaking on wine quality

¹H-NMR Metabolomics as a Tool for Winemaking Monitoring

The chemical composition of wine is known to be influenced by multiple factors including some viticulture practices and winemaking processes. 1H-NMR metabolomics has been successfully applied to the study of wine authenticity. In the present study, 1H-NMR metabolomics in combination with multivariate analysis was applied to investigate the effects of grape maturity and enzyme and fining treatments on Cabernet Sauvignon wines. A total of forty wine metabolites were quantified. Three different stages of maturity were studied (under-maturity, maturity and over-maturity). Enzyme treatments were carried out using two pectolytic enzymes (E1 and E2). Finally, two proteinaceous fining treatments were compared (vegetable protein, fining F1; pea protein and PVPP, fining F2). The results show a clear difference between the three stages of maturity, with an impact on different classes of metabolites including amino acids, organic acids, sugars, phenolic compounds, alcohols and esters. A clear separation between enzymes E1 and E2 was observed. Both fining agents had a significant effect on metabolite concentrations. The results demonstrate that 1H-NMR metabolomics provides a fast and robust approach to study the effect of winemaking processes on wine metabolites. These results support the interest to pursue the development of 1H-NMR metabolomics to investigate the effects of winemaking on wine quality

Identification and quantification of resolubilised polyphenols from fining precipitation

The aim of this study was to better understand the colloidal phenomenon involved in the fining process and to determine how many polyphenols are impacted in this process. Different types and compositions of fining agent were used to fine the wine. Some of them were pure and based on animal proteins and plant proteins, while others comprised a mixture of different matter, like PVPP and plant proteins, or PVPP, plant proteins and bentonite. Before and after fining, five different analyses were performed on the wine to characterise the polyphenolic composition and content. In order to determine polyphenol loss more precisely during fining, a new method was developed to quantify and characterise polyphenol precipitate using fining agents. This new method allowed us to find some drastic differences between the fining agents in term of total polyphenol precipitation, as well as in the composition of the precipitated compounds. Indeed, a group of anthocyanins present in low levels in wine (i.e., p-coumaroylated anthocyanins) became the most represented in the fining precipitate. Similarly, differences were also observed between the fining agents in the composition of precipitated condensed tannins. Fining agents without PVPP did not precipitate monomeric or dimeric flavan-3-ol or crown tannins. Some differences were also observed between the fining agent composed of plant-derived protein and that comprising gelatin. © 2023, International Viticulture and Enology Society. All rights reserved