Macrowine 2021
IVES 9 IVES Conference Series 9 Mean polymerization degree of proanthocyanidins of grape seeds, skins and wines from Agiorgitiko (cv. Vitis vinifera): Differences among vintages

Mean polymerization degree of proanthocyanidins of grape seeds, skins and wines from Agiorgitiko (cv. Vitis vinifera): Differences among vintages

Abstract

Grape phenolic compounds are very important constituents of red wine because, in addition to their antioxidant properties, they contribute to color, astringency and bitterness, oxidation reactions, interactions with proteins and ageing behavior of wines. The aim of our study was to assess the structural characteristics of grape and wine proanthocyanidins of Agiorgitiko variety and to evaluate the influence of the vintage year. Twelve vineyard locations were designated in the Nemea wine region. For three consecutive years (2012-2014), the grapes were harvested at technological maturity and the method of phloroglucinolysis was employed to determine the mean degree of polymerization (mDP) and subunit composition of the samples. Vintages 2012 and 2014 were characterized by extended botrytis infection, delayed sugar maturity and unripe tannins. In contrast, in 2013 the weather conditions were ideal, resulting in full sugar maturity, low botrytis infection and extended and full tannin maturation. These differences were depicted in our measurements: in 2013, the mDP values of the grape skins were higher than the corresponding values of the 2012 and 2014 samples, (especially those of the polymeric fractions) and were characterized by increased percentages of (-)-epicatechin units. Unlike grape skins, mDP values of grape seeds were not affected by vintage and their values were almost constant. Wine mDP values of 2013 were also increased compared to the relevant values of the other vintages; however, this increase was not as profound as that observed in grape skins, probably due to tannin modifications that occurred during vinification. Our results suggested that grape skin proanthocyanidin composition may be an indicator of grape tannin maturity. Among the skin proanthocyanidin constituents, it is suggested that (-)-epi-catechin content can be strongly influenced by the vintage year and its importance in wine quality should be further investigated.

Publication date: May 17, 2024

Issue: Macrowine 2016

Type: Poster

Authors

Stamatina Kallithraka*, Ioannis Paraskevopoulos, Katerina Kanellopoulou, Sofoklis Petropoulos, Yorgos Kotseridis

*Agricultural University of Athens

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Tags

IVES Conference Series | Macrowine | Macrowine 2016

Citation

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