Journal Of
Polyphenols

Abstract: Abstract Grape pomace is one of the most abundant solid by-products generated during winemaking, rich in bioactive compounds, i.e., proanthocyanidins. The major objective of this work was to characterize structurally oligomeric and polymeric proanthocyanidins of diff erent parts of grape pomace (seed, skin, and stem). Column chromatography techniques were used to isolate oligomeric and polymeric proanthocyanidins fractions from diff erent parts of grape pomace. The purifi ed grape seed proanthocyanidins were used to assess the effi ciency of the three most frequently-used acidic degradation methods, using benzyl mercaptan, phloroglucinol, and cysteamine as nucleophiles. The structural characterization of proanthocyanidins in the different parts of grape pomace was further performed by the phloroglucinolysis and ESI-MS analysis. The results showed signifi cant diff erences in the structural composition of proanthocyanidins among diff erent parts of pomace. A positive correlation was found between the mean degree of polymerization and percentage of galloylation, in both oligomeric and polymeric fractions. The results provided useful information for the preparation of diff erent proanthocyanidins products from grape pomace.

Key words: structural composition, proanthocyanidins, grape pomaces