Grape Seeds Proanthocyanidins: Advanced Technological Preparation and Analytical Characterization

A green solvent-free industrial process (patent pending) is here described for a grape seed extract (GSE) preparation (Ecovitis (TM)) obtained from selected seeds of Veneto region wineries, in the northeast of Italy, by water and selective tangential flow filtration at different porosity. Since a comprehensive, non-ambiguous characterization of GSE is still a difficult task, we resorted to using an integrated combination of gel permeation chromatography (GPC) and electrospray ionization high resolution mass spectrometry (ESI-HRMS). By calibration of retention time and spectroscopic quantification of catechin as chromophore, we succeeded in quantifying GPC polymers up to traces at n = 30. The MS analysis carried out by the ESI-HRMS method by direct-infusion allows the detection of more than 70 species, at different polymerization and galloylation, up to n = 13. This sensitivity took advantage of the nanoscale shotgun approach, although paying the limit of missed separation of stereoisomers. GPC and MS approaches were remarkably well cross-validated by overlapping results. This simple integrated analytical approach has been used for quality control of the production of Ecovitis (TM). The emerging feature of Ecovitis (TM) vs. a popular benchmark in the market, produced by a different technology, is the much lower content of species at low n and the corresponding increase of species at high n.

Automated summary

A green solvent-free industrial process was described for a grape seed extract preparation, with an analytical approach using gel permeation chromatography and electrospray ionization high resolution mass spectrometry. The integrated method successfully quantified polymers and detected over 70 species at different polymerization levels. This approach has been used for quality control of the production and revealed differences in species content compared to a popular benchmark product on the market.