Effects of Grapevine Leafroll-Associated Virus 3 on the Chemical and Sensory Properties of Cabernet Sauvignon Grape and Wine

Grapevine leafroll-associated virus (GLRaV) is a globally widespread disease that causes substantial economic losses in the wine industry. In severely affected vineyards, GLRaV can reduce grape yield by 20-40%. This study aimed to evaluate the effects of GLRaV infection on polyphenolic and volatile organic compound contents, as well as on the sensory profiles of the resulting wines. A comparative analysis was conducted between GLRaV-3-infected and healthy Cabernet Sauvignon grapes and their corresponding wines. Results show GLRaV-3 significantly alters grape and wine quality. In infected grapes, sugar content decreased while titratable acidity increased. Polyphenol composition was notably altered: phenolic acids and flavonols increased by 22.46% and 15.27%, respectively, whereas flavanols decreased by 17.86%. The levels of aldehydes and C₆ compounds also rose significantly in the berries. Wines produced from infected grapes showed lower alcohol content and reduced dry extract. Phenolic acids and flavanols were decreased, but total flavonols increased by 12.54%. Among volatile compounds, alcohols, phenols, and fatty acids were elevated, while esters declined by 13.36%. These chemical changes directly influenced sensory attributes. Compared with wines from healthy grapes, those from infected grapes exhibited improved tannin texture and longer aftertaste. However, they were inferior in color intensity, aroma intensity, body fullness, and varietal typicity.