Kiwi fruit (Actinidia deliciosa) are well-known and consumed products having antioxidant properties by means of specific compounds such as ascorbic acid, phenols and polyphenols (e.g., 6-hydroxy-7-(β-D-glucopyranosyloxi)coumarin, β-vanillic acid glucoside, caffeic, ferrulic acids and their glucosides, rutin, quercetin 3-O-β-D-rhamnoside, catechin, epicatechin, procyanidin tri- and tetramers).
The paper presents a study on the evaluation of antioxidant activity of kiwi fruit ethanolic extracts from various fruit parts using 2,2-diphenyl-1-picrylhydrazyl (DPPH·) method. Antioxidant activity was monitored for 15 minutes in the presence of 1 mM DPPH· solution and the DPPH· reaction rates were determined for two pseudolinear variation of this concentration (< 180 s and 3-15 minutes). Important antioxidant activity was obtained for kiwi fruit shell extracts obtained using 40-80% ethanol-water mixtures of 73.5-84.1%, while the antioxidant activity of the corresponding core extracts was in the range of 14.8-41%. On the other hand, the DPPH· reaction rates for the first pseudolinear range was significantly higher for shell extracts (0.2-0.5 μM/s) in comparison with the core extracts (< 0.1 μM/s). As a conclusion, the kiwi fruit shell extracts are more valuable for their antioxidant capacity, suggesting a much higher content of phenolic, polyphenolic, or enolic compounds.
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