Quercetin instability in red wines: Insights into precipitation and control approaches

One effect of climate change on grape composition is the increased biosynthesis of quercetin and its glycosides in response to UV-B radiation. High concentrations of quercetin in wine can exceed its solubility threshold, resulting in undesirable precipitation that negatively impacts clarity and consumer perception. This poses a challenge to producers in terms of both quality and economics. Starting from a survey of quercetin instability and its presence in wines, this review summarises the current understanding of the biochemical and physicochemical mechanisms that regulate quercetin stability and precipitation in red wines. It also covers the factors involved in quercetin extraction and stability during vinification and oenological strategies to counteract these effects. Taken together, these findings demonstrate that the stability of quercetin in red wines is governed by a complex interplay of factors, including anthocyanin-mediated copigmentation, pH, temperature, nucleation seeds and the broader phenolic composition of the wine matrix. By elucidating these mechanisms, the review provides a framework for predicting and managing quercetin precipitation, thereby supporting improved wine quality and colloidal stability in the challenging conditions imposed by climate change.