Abstract
Introduction: A tetrameric procyanidin characterized by an unusual B-type ‘crown’ (cyclic) structure was recently identified in wine.1-3 The presence of other ‘crown’ proanthocyanidins (PAC) congeners with various monomers composition and conformations was also hypothesized. These PAC display higher polarities than their non-cyclic analogues and also masses compatible with the isomeric A-type PAC. The latter ones have already been found in wine, although they are known to be more common in cranberries (Vaccinium sp.) and peanut skins (Arachis sp.).
Material & Methods: An optimized approach based on a C18 SPE purification was applied to hydrogen/deuterium exchange (HDX) HPLC-HRMS/MS to characterize these PAC in wine and other plant foods.
Results: The study enabled to identify a whole series of congeners (procyanidins and prodelphinidins) in wine that cannot be assigned to A-type PAC, but instead to B-type ‘crown’ (cyclic) structures.
Conclusion: The proposed approach allowed the identification of a series of unconventional proanthocyanidins (from tetramers to hexamers) in wine, with various substitutions. Their promising role as markers of authenticity and quality for wine is still under study.