Christopher Hall, Juliano Toniato, and Anita Oberholster*
*University of California, Davis, 1 Shields Avenue, Davis, CA, 95616 
(aoberholster@ucdavis.edu)

The wine industry around the world has seen an influx of smoke-related quality impact in wines due to smoke exposure. Wildfire risk has increased due to the increasing incidence of droughts and heat waves. During wildfires, high concentrations of volatile phenols (VPs) are released from wood; research has shown that these compounds can absorb into grape berries and reduce wine quality. There is currently no widely applied effective treatment in the vineyard to prevent absorption of VPs into grapes. Different carbon-infused materials can effectively protect the grapes from smoke in controlled smoke studies. However, placing black hoods over bunches could negatively impact grape ripening and phenolic evolution. This study investigated three different materials, loose- and tight-woven materials and a felt fabric, infused with activated carbon. These were placed as hoods over the bunches. In an additional treatment, the tight-woven fabric was strengthened with bird netting and placed on either side of the fruiting zone as a potentially less labor-intensive treatment. The treatments were applied after 100% veraison. Bunch samples were taken every week for seven weeks until harvest. HOBO temperature/humidity data loggers were placed inside each treatment to determine the impact of the fabric on bunch microclimate. Grapes are currently being analyzed to determine the phenolic profiles of the treated and untreated grapes by RP-HPLC, according to the method described in Panprivech et al. (2015). Although studies have shown that covering the grape bunches with activated carbon hoods is very effective in absorbing VPs in the atmosphere and protecting the grapes, this treatment is currently cost-prohibitive. Furthermore, if fabric protection comes at the cost of losing desired tannins, anthocyanins, or flavanols, it may not be a viable solution.

Funding Support: USDA-ARS