Effect of leaf removal and ultraviolet radiation on the composition and sensory perception of Vitis vinifera L. cv. Sauvignon Blanc wine

Background and Aims: This article studies the influence of the microclimate (light quantity, light quality and temperature) around fruit on the composition and sensory profile of South African Sauvignon Blanc wine. Materials and Results: We manipulated the light quantity in the bunch zone through leaf and lateral shoot removal, and light quality was altered by installing ultraviolet (UV) radiation-reducing sheets. We analysed wines made from fruit subjected to these treatments for chemical attributes pertaining to aromatic composition and assessed by a trained sensory panel. Variation in chemical and sensory attributes was found to be influenced by defoliation and UV radiation reduction. Control (no defoliation) was associated with green pepper, asparagus and grassy attributes, whereas wines from treatments where leaf and laterals shoot were removed were associated with tropical fruit attributes. Moreover, this study showed for the first time that UV radiation reduction significantly decreased the concentration of varietal thiols, linalool and some yeast derived compounds, such as esters and fatty acids, in the corresponding wines. Conversely, defoliation increased the concentration of thiols and linalool. Conclusions: Modification of the bunch microclimate can significantly affect wine composition and sensory properties, and therefore contribute to wine style. Significance of the Study: Understanding the effect of environmental factors (light and temperature) in the vineyard on wine composition and sensory attributes can assist winemakers and viticulturists in implementing appropriate viticultural practices (such as canopy manipulation) to assist in obtaining desired wine styles. .