Economical and eco-friendly isolation of anthocyanins from grape pomace with higher efficiency

Isolating anthocyanins from grape pomace, byproduct of red wine, becomes attracting for the multiple health beneficial effects of anthocyanins. Here in the ultrasound assisted anthocyanin isolation, parameters of time, ethanol concentration and pH, as well as temperature were individually optimized first. Then, surface response methodology was employed to further optimize the interactive and synergistic effect of these parameters. Optimal isolation condition was identified as the following: at the material liquid ratio of 1:15, 78.9 % of ethanol of pH 7.0 was utilized to extract at 63.8 °C for ∼48 min. Experimental yield with the optimal isolation conditions was 193.547 mg/100 g anthocyanin from grape pomace, almost twice as much as previously reported. Two more anthocyanins, delphinidin-acetylglucoside and cyanidin-coumaroylglucoside, were identified in the extract. With ethanol as the only organic solvent used, this isolation method is an economical, eco-friendly and more efficient, anthocyanin preparation method with simpler instrument setups.