David Campbell,* Misha Kwasniewski, and Joshua Lambert
*Penn State University, 660 Toftrees Ave, 402, State College, PA, 16803 
(dqc5715@psu.edu)

Hybrid winegrapes exhibit positive growing properties such as cold-hardiness and resilience to common plant pests and pathogens. They are economically significant in the Midwest and Northeastern United States, where Vitis vinifera does not grow easily. The quality of hybrid wines is limited, however, by deficiencies in the extraction of important grape polyphenols. Condensed tannins contribute to the sensory and health-promoting qualities of dry red wine, but in hybrid wines these compounds are found at very low concentrations. The extractability of grape tannins has been shown to vary by location and vintage, indicating that grapevine environment likely modulates this key quality parameter. Hybrid grape varieties were not included in this study, however, and it remains unclear whether certain environmental conditions can mitigate or worsen the low tannin extractability observed in hybrids. To examine this question, we measured tannin extractability in one hybrid and one V. vinifera cultivar harvested from seven commercial vineyards in Pennsylvania. Tannins were extracted from each grape sample in triplicate using model wine and an exhaustive extraction, then quantified using RP-HPLC. Extractability was measured as the ratio of tannins extracted in model wine to total grape tannins. Grapevine environmental data was collected using on-site weather stations and correlated with phenolic extractability.

Funding Support: National Institute of Food and Agriculture, U.S. Department of Agriculture, through the Northeast Sustainable Agriculture Research and Education program