Project Title: Characterization of Bitter and Astringent Proanthocyanidins during
- Dr. Susan E. Ebeler, Department of Viticulture & Enology, University of California, Davis,
- Dr. Hildegarde Heymann, Department of Viticulture & Enology, University of California,
Polyphenols, including proanthocyanidins (i.e., tannins), are widely distributed in foods and
beverages, including grapes and wines and they are key constituents impacting bitter and
astringent perception. Due, at least in part, to their chemical complexity, the changes in
proanthocyanidin concentration and chemical structure that occur during winemaking and that
impact sensory properties have not been fully evaluated.
During the past year we have developed an ultra-high performance liquid chromatography
quadrupole time-of-flight mass spectrometry (UHPLC-qTOF MS) approach to characterize the
subunit composition and molecular weight/average degree of polymerization of wine
proanthocyanidins. Wines with different maceration treatments were analyzed and we are in the
process of completing the data analysis and comparison of the treatments. This work is
beginning to provide important insight into the impact of maceration treatments on
proanthocyanidin composition of wines.