Effects of sunlight exposure on flavonol content and wine sensory of the white winegrape grechetto gentile

The aim of this research was to study the effect of sunlight exposure on the composition of white grapes and 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-treated grapes were conducted following a standardized protocol designed to identify 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 LR, and were also higher in the corresponding wines. Berry tannins showed only minor changes in response to the higher solar irradiance from LR and were not different in the wines. In 2014, wine from the LR-treated vines was judged to be more bitter and astringent, whereas no difference was found between wines of 2015. The higher concentration of flavonols may have contributed to the higher intensity of phenolic mouthfeel in the first year, whereas the very high pH and alcohol content of all the wines in the second year may have masked differences in perception of astringency and bitterness.