Abstract
The antioxidant activity of 80% ethanol and 70% acetone extracts of stems from red and white grapes (Vitis vinifera) used in wine industry were evaluated to determine their feasibility as natural antioxidants. The results showed that all grape stem extracts were rich in total polyphenolic compounds and flavanols and had clear antioxidant activities. The free radical-scavenging capacity of the extracts was determined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. The extracts obtained from red grape stem present EC50 values of 0.14 g dm/g DPPH (acetone extract) and 0.20 g dm/g DPPH (ethanol extract) while the extracts obtained from white grape stem present EC50 values of 0.26 g dm/g DPPH (acetone extract) and 0.37 g dm/g DPPH (ethanol extract). There are significant correlations between the total content of polyphenols and the antioxidant activity (R2 = 0.9352) and between the flavanols content and the antioxidant activity (R2 = 0.9404) of the grape stem extracts obtained.
Highlights
There is a growing interest in the exploitation of the residues generated by the food industry, and this is very attractive to the vegetable/beverage industry, as they will have to sustain increasing costs for treating these solid and liquid wastes
The results showed that all grape stem extracts were rich in total polyphenolic compounds and flavanols and had clear antioxidant activities
The extracts obtained from red grape stem present EC50 values of 0.14 g dm/g DPPH and 0.20 g dm/g DPPH while the extracts obtained from white grape stem present EC50 values of 0.26 g dm/g DPPH and 0.37 g dm/g DPPH
Summary
There is a growing interest in the exploitation of the residues generated by the food industry, and this is very attractive to the vegetable/beverage industry, as they will have to sustain increasing costs for treating these solid and liquid wastes. This is true in wine production, which affords a substantial volume of solid organic material. Free radicals have been claimed to play a key role, in affecting human health by causing life-threatening illnesses by cell degeneration, such as cancer and cardiovascular diseases. Polyphenols are known to be powerful antioxidants as they are hydrogen donating free radical scavengers [6,7,8,9]
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