Quali-quantitative analysis by LC/DAD and GPC of the polyphenols of "Uva Di Troia Canosina" grape seeds for the development of an industrial nutraceutical product

The quali-quantitative determination of the principal components of “uva di Troia canosina” seed extracts by LC/ DAD analysis and the optimization of the extraction and purification processes for the development of an industrial nutraceutical product, are described. Two different fractions of seeds collected at different stages of fermentation were compared: “Tesi” 2 when there is a spontaneous stratification of the seeds at the bottom of the recipient and “Tesi” 4 at the end of fermentation. Percolation was applied and compared to maceration and the purification step carefully evaluated to obtain extracts free of contaminant species endowed with polyphenolic content comparable to commercial preparations such as Leucoselect® (Indena, SpA, Italy), Vitis Vinifera extract 95% (seeds), Vitis Vinifera dry extract 95%, Biovin grape seed and vinasse extract. (Farmalabor, Italy). In particular, “Tesi” 2 extract obtained by percolation and purified with a LLE extraction with ethyl acetate showed a polyphenolic content similar to Leucoselect®. From the quantitative analyses it was evident, as expected, that “Tesi”2 has a higher polyphenolic content compared to “Tesi” 4, because during vinification the must extracts polyphenols from the seeds. On the other hand, “Tesi” 4 is particularly convenient since it is easily obtained and very economical, being a waste product. The residual content of organic solvents (ethanol and ethyl acetate) and water was assessed in the grape extracts according to ICH rules by means respectively of HS/GC and Karl Fisher titration in order to meet the requirements for commercialization. Furthermore, the high molecular weight polyphenolic fraction of our extracts was investigated through gel permeation chromatography (GPC) and compared to that of Leucoselect®.