Characterization of grape and wine proanthocyanidins of Agiorgitiko (Vitis vinifera L. cv.) cultivar grown in different regions of Nemea

Proanthocyanidin structure was determined in skins and seeds isolated from Vitis vinifera cv. Agiorgitiko grapes and the corresponding wines. The experiment was conducted in twelve vineyards of Peloponnese Greece (Nemea) for three consecutive years. Proanthocyanidins were extracted with organic solvents and the average degree of polymerization (mDP) of oligomeric and polymeric fractions was determined by phloroglucinolysis followed by HPLC-UV and MS detection. Furthermore, percentages of galloylation (G%) and% prodelphinidins (P%) were estimated in grape extracts and wines. The predominant PA subunits were (−)-epicatechin (EC) and (−)-epigallocatechin (EGC) in seeds and skins respectively. Seed PAs were highly galloylated and more polymerized than skin PAs. Although wine subunit composition resembled that of grape skins, relation between grape and wine PAs could not be established. The harvest year had an influence on skin PAs while the altitude affected only seed PAs. The low values determined for mDp and%G combined with the abundance of EGC subunits in Agiorgitiko grape and wine PAs would be expected to be associated with lower astringency perception.