Characterization of Bitter and Astringent Proanthocyanidins during Winemaking

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.

We have completed development and validation of 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 were able to demonstrate differences in proanthocyanidin composition as a function of maceration treatment. This work provides important insight into the impact of maceration treatments on proanthocyanidin composition of wines.