An effective method for the semi-preparative isolation of high-purity anthocyanin monomers from grape pomace

Grape (Vitis vinifera L.) pomace, the residue of red wine production, is a good source material for production of anthocyanins. In this study, an effective and simple method for semi-preparative isolation of anthocyanins from grape pomace was developed. Ultrasonication with acidified MeOH was used to extract anthocyanins, with 56.15 mg total anthocyanins being obtained from 50 g grape pomace. Crude extracts were purified by XAD-7HP column chromatography, followed by isolation of the anthocyanin mixtures using semi-preparative HPLC, and subsequent identification of anthocyanin monomers by HPLC-DAD-MS/MS. Fourteen anthocyanins were isolated with high purities (≥90%), among which were non-acylated and acylated anthocyanins, and their cis and trans isomers. It is believed this is the first time that nearly all primary anthocyanin monomers in grapes have been isolated simultaneously using a single-step semi-HPLC procedure. The findings of this study will contribute to further research on anthocyanin monomers and profitable utilization of grape pomace.