Antioxidant Activities of Extracts Obtained from Winery By-Products

摘要

In Europe the utilization of renewable sources with environmentally accepted technologies are crucial. The reuse of winery by-products to be converted to high valued products can be remarkable according to the fact, that grape wastes are available in high amounts and they are rich in phenols. Polyphenols possess strong antioxidant activity, therefore the extracts from winery by-products can be treated as health-preventing functional food additives. Using supercritical carbon-dioxide extraction solvent-free extracts can be produced increasing the added value of the products. In this work several winery by-products (grape seeds, fermented grape seeds, pomace, fermented pomace) were tested. Conventional solvent extraction using solvents with different solvent properties (n-hexane, ethyl-acetate, iso-propanol, ethanol) and supercritical carbon-dioxide extraction were carried out The total phenolic, flavonoids and tannin constituents of extracts and their residuals were measured with spectrophotometer The fatty acid composition of the extracts were revealed using GC method The antioxidant properties of winery by-products, their extracts and their residuals were revealed in aqueous and lipophilic in vitro systems. The hydrogen-donor activities in the presence of 1,1-diphenyl-2-picrylhydrazyl free radical were determined, meanwhile applying the lipid oxidation assay (Rancimat method) the antioxidant properties of the extracts dissolved in edible oil (test system) were measured. On the basic of the results it can be concluded that the products obtained from winery by-products possess high biological values; therefore their usages are reasonable for well-defined purposes (food-, cosmetic or pharmaceutical industries) Natural oils, waxes, and flavours can be extracted and due to their antioxidant properties longer shelf-live can be achieved.