Screening of Italian red wines for quercetin precipitation risk index

Abstract

Quercetin (Q), a phenolic compound released from grape skins during red wine maceration, has been identified as a source of instability in bottled wines, particularly Sangiovese, due to crystallisation. This phenomenon represents an economic challenge for producers and affects wine clarity and consumer perception. Recent research [1;2] has highlighted the influence of phenolic composition, particularly anthocyanin concentration, on Q stability in model solutions. Results suggest that co-pigmentation phenomena can increase Q solubility, thereby reducing the risk of crystallisation. Based on these results, the aim of this study was to validate these findings in real red wines and to develop a predictive index of Q precipitation risk. We analysed 32 monovarietal red wines from the same harvest that differed significantly in phenolic composition, focusing on the quantification of quercetin glycosides (Q-Gs) and aglycone in the wine bulk and in the sediment when present at different time points. Hydrolysis of Q-Gs occurred in all wines during the first 8 months, but only in 9 wines Q was detected in insoluble precipitates. Considering all wines no clear precipitation threshold could be determined. Partial least squares (PLS) regression showed that the most influential risk categories for the risk of Q precipitation included not only initial Q, Q-Gs, but also pH and tannin content. Our results contribute to a deeper understanding of the factors influencing Q stability in red wines, with implications for producers seeking to mitigate crystallisation problems, with the ultimate aim of providing producers with a practical tool to manage and mitigate precipitation risks.

References

[1] Luciano, A., Picariello, L., Forino, M., Moio, L., & Gambuti, A. (2024). Anthocyanins and nucleation seeds are key factors affecting quercetin precipitation in red wines. Journal of the Science of Food and Agriculture, 104(9), 5163-5175.

[2] Lanati, D., Cascio, P., Pollon, M., Corona, O., & Marchi, D. (2022). Solubility of quercetin in wines. South African Journal of Enology and Viticulture, 43(2), 146-156.