Browning susceptibility of white wine and antioxidant effect of glutathione

P>Glutathione (GSH) content and other physicochemical parameters of thirteen white wines originated from Lebanon were studied in relation to their browning capacity; the impact of pH, total sulphur dioxide and total phenol content into the browning susceptibility of the wine was shown. The effect of GSH, added to the wine at different concentrations, on the total phenol content was studied at 55 degrees C during 8 days of accelerated oxidation. GSH addition resulted in significantly higher total phenol content only on day 0 of the test. GSH was shown to be readily oxidised in these conditions: even on day 0, there was a considerable reduction (up to 73%) in GSH level. Moreover, after 8 days of oxidation, GSH concentration in all studied samples ranged from 4.79 to 5.11 mg L-1; these values were close to GSH value in control wine (without added GSH) on day 0. On the contrary, GSH appeared to contribute significantly to the wine stability, which might have been via the increase of reduced phenolic pool. GSH addition appeared to have an improving effect on the organoleptic qualities of the wine.