Comparative flavan-3-ol composition of seeds from different grape varieties

The flavanol composition of the seeds of 17 varieties of grape cultivated in the main wine-producing areas of Castilla-Leon (Spain) was studied. Twenty-seven different flavan-3-ols of procyanidin type were found, but no prodelphinidins were detected. Minor amounts of four hydrolyzable tannins were also present in the seed extracts of most of the grapes analyzed. All the varieties contained galloyled flavanols, such that their presence could be considered characteristic of the grape seed composition. Some proposals concerning the biosynthesis of flavan-3-ol in the grape seed are also advanced taking into account the compounds found.