Comparison of extracts prepared from plant by-products using different solvents and extraction time

By-products obtained after red fruit processing still contain large amounts of polyphenols, especially anthocyanins which act as antioxidants. The effect of solvent and extraction time on the yield of extracted antioxidants from grape, black and red currant by products (marc) was investigated. Ethanol and methanol extracts of red and black currant contain twice more anthocyanins and polyphenols than water extracts, extracts made from grape marc had seven times higher values than water extracts. In water extracts the yields of polyphenols decreased, while in methanol and ethanol extracts their content increased with the time of extraction. The highest antioxidant activity was in extracts made from black currant marc, the lowest was in extracts made from red currant marc. Grape extracts had high antioxidant activity due to its high content of polyphenols. (c) 2004 Elsevier Ltd. All rights reserved.