Antioxidant action of glutathione and the ascorbic acid/glutathione pair in a model white wine.
Sonni, F.; Clark, A. C.; Prenzler, P. D.; Riponi, C.; Scollary, G. R.; Journal of Agricultural and Food Chemistry 2011, 59 (8) 3940–3949
Glutathione was assessed individually, and in combination with ascorbic acid, for its ability to act as an antioxidant with respect to colour development in an oxidizing model white wine system.
Glutathione was utilized at concn. normally found in wine (30 mg/l), as well as at concn. 20-fold higher (860 mg/l), the latter to afford ascorbic acid (500 mg/l) to glutathione ratios of 1:1. The model wine systems were stored at 45°C without sulfur dioxide and at saturated O2 levels, thereby in conditions highly conducive to oxidation.
Under these conditions the results demonstrated the higher concn. of glutathione could initially provide protection against oxidative coloration, but eventually induced colour formation.
In the period during which glutathione offered a protective effect, the production of xanthylium cation pigment precursors and o-quinone-derived phenolic compounds was limited.
When glutathione induced coloration, polymeric pigments were formed, but these were different from those found in model wine solutions without glutathione.
In the presence of ascorbic acid, high concn. of glutathione were able to delay the decay in ascorbic acid and inhibit the reaction of ascorbic acid degradation products with the wine flavanol compound (+)-catechin. However, on depletion, the glutathione again induced the production of a range of different polymeric pigments.
These results highlight new mechanisms through which glutathione can offer both protection and spoilage during the oxidative coloration of a model wine.
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Published on 12/05/2012