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| - Assessment of the Production of Antioxidants fromWinemaking Waste Solids
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| - Winemaking waste solids (WS, resulting from red grapes after fermentation and distillation to recoverspirits) were subjected to various processing schemes for isolating fractions with antioxidant activity.The liquors entrapped in WS as received were separated by pressing and freeze-dried to yield afraction with antioxidant activity (measured as DPPH radical scavenging capacity) comparable tothose of synthetic antioxidants. A second approach based on the direct processing of raw WS insulfuric acid medium under fixed operational conditions and further extraction of hydrolysis liquorswith ethyl acetate enabled the isolation of a fraction with higher antioxidant ability at an improvedyield. The most favorable approach started with a washing stage leading to liquors (which were directlyfreeze-dried to yield 1.20 g of extract/100 g of oven-dry WS and presented an EC50 of 0.41 g ofextract/L) and washed solids, which were dried and subjected to hydrolytic processing (i) with wateras a reactive in an autocatalyzed reaction (autohydrolysis) or (ii) with sulfuric acid solutions to givean ethyl acetate-soluble fraction with improved antioxidant properties (EC50 in the range of 0.18−0.40 g/L). Samples from washing liquors and processing of washed solids in aqueous medium weresubjected to chromatographic fractionation and analysis to give isolates with remarkable antioxidantactivity (with EC50 as low as 0.07 g/L) and to identify their major components. Keywords: Acid hydrolysis; analysis; antioxidant activity; autohydrolysis; ethyl acetate; red grape;solid wastes; winemaking
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