Affiliation:
1. Department of Viticulture and Enology University of California Davis California USA
2. Capfall Consulting Napa California USA
3. Functional Phenolics LLC Corvallis Oregon USA
Abstract
AbstractBACKGROUNDHistorically, the effect of wine grape shading on flavonoids has investigated the impact of light incidence on proanthocyanidin (PA), flavonol, or anthocyanin concentration. In addition to concentration, the current experiment was designed to look at changes in PA composition, size and tannin activity through ripening. Tannin activity is a methodology for assessing the impact of structure and size on the affinity of tannin towards a hydrophobic surface and is considered to be a proxy for predicted astringency descriptive quality. In 2016 a shade cloth study was imposed on Cabernet Sauvignon on Mt Veeder, within the larger Napa Valley viticultural area. A control, which was unshaded, and two treatments consisting of 40% and 80% shade were applied at the onset of veraison.RESULTSResults showed significant differences in the composition and concentration of anthocyanins throughout ripening. Compositional differences in PA were also observed, where shaded treatments had a significantly higher proportion of galloylated subunits. The molecular mass of the extracted tannin was significantly lower in the unshaded control than in the 80% shade treatment. These factors led to a lower measured tannin activity in extracts from exposed fruit.CONCLUSIONThis work suggests that manipulation of canopy architecture, such as artificial shading, leads to changes in berry pigmentation, tannin composition and activity. These results show that the astringency and mouthfeel characteristics of a wine may be altered by vineyard management practices. © 2023 Society of Chemical Industry.
Funder
American Vineyard Foundation
Subject
Nutrition and Dietetics,Agronomy and Crop Science,Food Science,Biotechnology