标题：An Investigation on Factors Affecting Recovery of Antioxidant Phenolics and Anthocyanins from Red Grape ( Vitis vinifera L.) Pomace Employing Water/Ethanol-Based Solutions
摘要：Extractions were performed using non-toxic media composed of water/ethanol mixtures and hydrochloric, acetic or tartaric acid. Recovery efficiency was assessed by monitoring the antiradical activity (AAR) of extracts and several indices related to their polyphenolic composition, including total polyphenol, total flavonoid, total flavanol, total anthocyanin and condensed tannin (proanthocyanidin) content. Extracts with the highest AAR values were obtained with 57% ethanol, a solvent system that was also favourable in obtaining high total polyphenol and total flavonoid yields, which amounted 7259 and 7222 mg/100 g dry weight, respectively. The highest anthocyanin yield was however achieved with 85.5% ethanol (266.2 mg/100 g dry weight). None of the acidification agents used provided extracts with increased polyphenol levels and AAR. Addition of SO2 (0.01%, w/v) to 57% ethanol, however, resulted in maximisation of AAR (2.9 mM TRE/g dry weight), although anthocyanin recovery was not maximal (186.9 mg/100 g dry weight). It is suggested that efficient recovery of antioxidant phenolics and anthocyanins from by-products of red vinification can be achieved employing simple extracting media composed of ethanol, but more active, in terms of antioxidant activity , extracts can be obtained with addition of a low amount of SO2. Ethanol is a bio-solvent that can also be obtained from wine-industry wastes and thus the implementation of similar techniques may potentially provide the basis for a sustainable process of integrated exploitation of vinification by-products.
