|Sunburn on Chardonnay.|
Studies of Chardonnay wine quality showed that wine made from sunburned grapes is darker with bitter characteristics. Preventing sunburn is one of the key factors to achieving wine quality in Chardonnay.
Sun exposure in all white wine grapes may result in increased phenolic concentration (Macaulay and Morris, 1993), and berry shrivel and browning (Tarara et al. 2000).
Interestingly the application of commercial ‘sunscreen’ products (calcium carbonate and kaolin clay) can prevent this, but has not been widely used in the marketplace by grape growers.
Macaulay, L. E., and Morris, J. R. (1993) Influence of Cluster Exposure and Winemaking Processes on Monoterpenes and Wine Olfactory Evaluation of Golden Muscat. Am. J. Enol. Vitic. 44:2:198-204
Tarara, J. M., Ferguson J. C., and Spayd, S. E. (2000) A Chamber-Free Method of Heating and Cooling Grape Clusters in the Vineyard. Am. J. Enol. Vitic. 51:2:182-188