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Antioxidant profile of commercial oenological tannins determined by multiple chemical assays
Author(s) -
Magalhães L. M.,
Ramos I. I.,
Reis S.,
Segundo M. A.
Publication year - 2014
Publication title -
australian journal of grape and wine research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.65
H-Index - 77
eISSN - 1755-0238
pISSN - 1322-7130
DOI - 10.1111/ajgw.12058
Subject(s) - chemistry , oxygen radical absorbance capacity , abts , dpph , antioxidant , proanthocyanidin , winemaking , wine , ellagic acid , polyphenol , lipid peroxidation , radical , food science , organic chemistry , chromatography
Background and Aims The addition of oenological tannins during winemaking is a longstanding technological practice. To assist such a practice, knowledge of their antioxidant properties is an asset for understanding their role in redox processes occurring in wine. Hence, the aim of this work was to assess the antioxidant profile of oenological tannins from several botanical sources, which are usually applied at different winemaking steps. Methods and Results Several antioxidant assays, including the ability to reduce copper( II ) assay (CUPRAC), the scavenging capacity against 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS) and 2,2‐diphenyl‐1‐picrylhydrazyl radicals (DPPH), and the peroxyl radical scavenging capacity (oxygen radical absorbance capacity assay, ORAC) were applied. The concentration of phenolic substances and the ability to chelate iron( II ) (ICA) were also determined. A significant correlation was obtained between the concentration of phenolic substances and the copper(II) reducing antioxidant capacity ( R = 0.89), and the 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonate) ( R = 0.86) and 2,2‐diphenyl‐1‐picrylhydrazyl ( R = 0.86) assays. No such correlation was observed ( R = 0.15) with the oxygen radical absorbance capacity assay. Conclusions The highest radical scavenging capacity was attained for oenological tannins composed of gallotannins, while those containing ellagic acid were able to chelate iron( II ) strongly, preventing the oxidative damage mediated by F enton‐based reactions. Condensed tannins demonstrated a significant ability to scavenge peroxyl radicals, which represents a powerful antioxidant mechanism to prevent lipid peroxidation. Significance of the Study The chemical antioxidant profile of oenological tannins displayed in radar charts provides valuable information for winemakers and manufacturers of oenological tannins.