Effects of Sunlight Exposure on Flavonol Content and Wine Sensory of the White Winegrape Grechetto Gentile

Abstract

This aim of this research was to study the effect of sunlight exposure on the composition of white grape and on wine sensory attributes. In 2014 and 2015, vines of the white winegrape Grechetto gentile were subjected to cluster zone leaf removal (LR) after fruit set. Small-scale vinifications of Control and LR grapes were conducted following a standardized protocol designed to verify differences in astringency and bitterness, and the relationship between these mouthfeel attributes and the concentrations of phenolic compounds was investigated. In both years, berry flavonols increased after cluster zone leaf removal, and these compounds were also higher in wine. Berry tannins showed only minor changes in response to the higher solar irradiance, and no difference was detected in wines. In 2014, wine of LR vines was judged more bitter and astringent, while no difference was found between wines of 2015. The higher intensity of phenolic mouthfeel in the first year suggested a large involvement of the higher concentration of flavonols also found in that year, while in the second year, the very high pH and alcohol content of all the wines could have masked differences in the perception of astringency and bitterness.