Mani Awale, Connie Liu, and Misha Kwasniewski*
*Grape and Wine Institute, University of Missouri-Columbia, 135 Eckles Hall, University of Missouri- Columbia, Columbia, MO 65211 (kwasniewskim@missouri.edu)

Grape-derived volatiles play an important role in wine aroma and contribute to overall wine quality. Free volatiles and non-volatile precursors, including glycosides, are present in grapes. The aroma precursors released during winemaking due to acidic or enzymatic hydrolysis give varietal characteristics to a wine. We investigated grape-derived volatiles in Cabernet Sauvignon, a popular Vitis vinifera grape, and an interspecific hybrid, Norton. Although Norton possess important viticultural traits such as cold hardiness and disease tolerance that have made it economically important to Missouri, they are less popular than the vinifera wines globally. While earlier efforts have been made to determine the volatile profile of hybrid wines using targeted approach, we opted for a more inclusive, non-targeted metabolomics approach to investigate the differences in Norton and Cabernet Sauvignon grapes and wines. Both free and bound volatiles were profiled in grapes and free volatiles, in wines. Twenty-one samples of Norton and Cabernet Sauvignon grapes, from different vintages and sites, along with their 10 different commercial wines, were analyzed using headspace SPME-GCMS. Data was processed using XCMS to identify features different between the two cultivars. 825, 697, and 403 features were found to be different for free grape volatiles, bound volatiles, and wine volatiles, respectively, at a minimal 0.05 significance level and 1.5-fold change. Those features were used to identify and quantify odor-active compounds that varied in concentration, including β-linalool, β-damascenone, β-ionone, eugenol, and methyl salicylate. We found no compounds present in one that was absent in the other cultivar, however, the concentrations of the compounds identified were always higher in Norton than Cabernet Sauvignon. Identification of these differences is critical to optimize management of Norton and useful in varietal development, where the end goal is disease-tolerant fruit with a widely accepted aroma profile.

Funding Support: USDA