Sequential fractionation of grape seeds into oils, polyphenols, and procyanidins via a single system employing CO2-based fluids

Pure supercritical CO2 was used to remove >95% of the oil from the grape seeds. Subcritical CO2 modified with methanol was used for the extraction of monomeric polyphenols, whereas pure methanol was used for the extraction of polyphenolic dimers/trimers and procyanidins from grape seed. At optimum conditions, 40% methanol-modified CO2 removed >79% of catechin and epicatechin from the grape seed. This extract was light yellow in color, and no higher molecular weight procyanidins were detected. Extraction of the same sample after removal of the oils and polyphenols, but now under enhanced solvent extraction conditions using methanol as a solvent, provided a dark red solution shown via electrospray ionization HPLC-MS to contain a relatively high concentration of procyanidins. The uniqueness of the study is attested to by the use Of CO2-based fluids and the employment of a single instrumental extraction system.