Identification and quantification of furaneol-β-glucoside by LC-MS/MS in berries and wine during ripening and winemaking

Abstract

Furaneol® (2,5-dimethyl-4-hydroxy-3(2H)-furanone) is a key wine aroma compound reminiscent of strawberry and caramel notes and, together with other furanones and lactones, contribute to overwhelming dried fruit aromas. Under climate change, high temperatures and accelerated ripening are expected to increase furaneol amount in wines. In this context, understanding the pathway responsible for its formation is essential. A glycosylated form (Furaneol-β-glucoside; Fur-β-Glu) has already been reported in aromatic cultivar Muscat Bailey. However, its identification in non-aromatic Vitis vinifera cultivars remains elusive and the link between Fur-β-Glu and Furaneol in wine has never been demonstrated. This study aimed to quantify Fur-β-Glu in grapes, must and wine, assessing variables like variety (Vitis vinifera cultivars), maturity level, vintage effect, as well as the contribution of yeast metabolism to the formation of furaneol in wine. Fur-β-Glu (commercial standard) was identified by LC-HRMS and quantified using a validated LC-MS/MS method. The method was applied to analyze musts and wines from a wide range of white and red cultivars collected in France (Bordeaux, n=9) and southern Italy (Campania, n=5) across multiple vintages (2019, 2022, and 2025). Fur-β-Glu was quantified in Merlot grape berries at different maturity stages. We confirmed that more than 90% of Fur-β-Glu is localized in berry skin regardless of the maturity stage. In terms of concentration, it was found at levels of up to 15 µg/L in musts and from 10 to 55 µg/L in the resulting red wines obtained from different cultivars harvested at different maturity levels. Fur-β-Glu concentration in must, in the most part of the variety under our analysis, decreased during over-ripening, whereas significant increase was detected in wine made with these overripe grapes. Among the 14 cultivars analyzed, highest Fur-β-Glu levels were detected in Merlot wines (35-55 µg/L), and lowest levels in Cabernet Sauvignon, Touriga Nacional and Carmenere wines (2-12 µg/L). AF trials on musts spiked or not with known precursor concentrations led us to validate for the first time Fur-β-Glu as precursor of furaneol in red wine through putative enzymatic hydrolysis. These findings may help, in a near future, to improve the varietal selection, harvest timing, and maceration strategies to preserve wine aroma balance.