S. KOUNDOURAS., ENVIRONMENTAL AND VITICULTURAL PRACTICE EFFECTS ON THE PHENOLIC COMPOSITION OF GRAPES: IMPACT ON WINE SENSORY PROPERTIES, PAG. 1 WWW.INFOWINE.COM, INTERNET JOURNAL OF VITICULTURE AND ENOLOGY, 2018, N. 2/2 ENVIRONMENTAL AND VITICULTURAL PRACTICE EFFECTS ON THE PHENOLIC COMPOSITION OF GRAPES: IMPACT ON WINE SENSORY PROPERTIES Stefanos KOUNDOURAS Laboratory of Viticulture, School of Agriculture, Faculty of Agriculture, Forrestry and Natural Environment, Aristotle University of Thessaloniki, University Campus 541 24 Thessaloniki, Greece E-mail: skoundou@agro.auth.gr Phenolic compounds in grapes: localization and biosynthesis Grape-derived secondary metabolites are the principal sources of wine color, aroma and flavor. Among them, phenolic compounds are classified as non-flavonoid (benzoic and cinamic acids and stilbenes) and flavonoid (anthocyanins, flavonols and tannins). Anthocyanidin R1 R2 R3 R4 R5 R6 R7 cyanidin OH OH H OH OH OH H delphinidin OH OH H OH OH OH OH petunidin OH OH H OH OMe OH OH peonidin OH OH H OH OMe OH H malvidin OH OH H OH OMe OH OMe Figure 1: General structure of grape anthocyanidins Among the latter, anthocyanidins are pigmented compounds located in the skins of grape berries in red cultivars while tannins derive from both skins and seeds of berries. Anthocyanins are glycosides of anthocyanidins. In red grape Vitis vinifera varieties, the most common 3-O-glucoside derivatives of anthocyanidins are delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, petunidin-3-O-glucoside, peonidin-3-O-glucoside, and malvidin-3-O-glucoside, the latter being the most abundant (Figure 1) (Kallithraka et al. 2005). Vitis labrusca and Vitis rotundifolia grapes contain both anthocyanidin monoglucosides and diglucosides. Although anthocyanin profile is mostly genetically driven, the relative amounts of anthocyanins were also shown to depend to a lesser extent on the degree of grape ripeness (Roggero et al. 1986) and on the growing conditions (Kotseridis et al. 2012)