An enzymatic extraction of proanthocyanidins from País grape seeds and skins

Proanthocyanidins (PAs) from the skins and seeds of País grapes were obtained by enzymatic extraction by using three enzymes (pectinase, cellulase and tannase) and an enzymatic blend to increase the phenol concentrations and reduce the PA molecular size. The total phenol concentrations (as indicated by Folin-Ciocalteu reagent), mean degree of polymerisation (mDP), galloylation percentage (%G) and structural proportion (phloroglucinolysis) were analysed, in addition to the extract's capacity to inhibit angiotensin I-converting enzyme (ACE) activity. On grape skins, pectinase had the greatest effective on the release of total phenols, to 0.01g/ml solid/liquid (S/L) and 1% enzyme/substrate (E/S). On grape seed, the three enzymes were effective in increasing the phenolic extraction (p<0.05). The effects of enzymes on the mDP and %G of the extracts were related to their enzymatic activity. All the extracts inhibited ACE, but ACE inhibition was thought to be improved by the increased number of terminal units in the seed samples.