Phytosterols in grapes and wine, and effects of agrochemicals on their levels

To improve the knowledge on the chemical diversity and complexity of grapevine, we investigated the plant sterol content of berry and seed tissues at pre-véraison and véraison stages in 2009 and 2010. We also assessed the effects of benzothiadiazole and chitosan elicitors on content of sterols in grapes and their levels in the corresponding experimental wines. β-Sitosterol was the most abundant component in berry tissues, in both growth stages and years, with the highest amounts in the flesh and skin at pre-véraison and véraison, respectively. Stigmasterol and campesterol were present in lower concentrations in both phenological stages and vintages. During the transition from pre-véraison to véraison, phytosterols decreased in all tissues, in both years, apart from stigmasterol in seeds. In addition, the results showed that the plant activators were more effective than conventional fungicides in rising the levels of sterols, particularly β-sitosterol, both in grapes and in microvinificates.