Identifying factors influencing Hydroxytyrosol in wines: Varietal selection, organic management, and yeast strategies in rosé and white wine production

Hydroxytyrosol (HT) is a low-toxic antioxidant with relevant biological properties. The objective of this study is to analyze natural HT production during rosé and white winemaking using various grape cultivars (including an organic one) and different yeast inoculation strategies. The UPLC-MS/MS method was validated to determine HT and related compounds. Six red and seven white grape varieties were harvested in southern Spain. Commercial yeasts (Saccharomyces cerevisiae) and wild yeasts were tested. As key findings, Rosé wines (Rome Variety) showed higher HT levels (1800 ng/mL) than white wines (Mantuo de Pilas variety) (300 ng/mL). Organic grapes produce up to five times more HT than conventional ones. Moreover, HT production was enhanced in wild yeasts compared with commercial yeasts (CY). In addition, wine lees and pomace retained considerable amounts of HT. To conclude, the formation of natural HT during winemaking varies by grape type and fermentation method.