Quality improvement of a white and a red wine with less sulphur dioxide by the addition of a mixture of glutathione, caffeic acid and gallic acid

The effect of a mixture of glutathione, caffeic acid and gallic acid, at 20 mg/L, 60 mg/L and 20 mg/L respectively, on the quality of a white and a red wine with less than the typical SO2 was studied. The mixture was added in Vinho Verde white wine containing 20 mg/L free SO2 at bottling. Wine quality was evaluated in comparison with wine with 20 mg/L and control wine with typical (35 mg/L) free SO2. By the storage time, wine in which the mixture was added appeared to be of better quality than that with 20 mg/L free SO2. It exhibited higher scores in sensory attributes and lower degree of oxidation as indicated by the chromatic characteristics L*, b* and C*. Wine with typical SO2 exhibited higher scores in sensory analysis than the others. The same mixture was also added into a Merlot-Cabernet Sauvignon blend red wine at bottling. Wine quality was evaluated during storage in comparison with wine with 25 mg/L and control wine with typical (35 mg/L) free SO2. By the storage time, wine in which the mixture was added appeared to be of better sensory quality than that with 25 mg/L free SO2. Moreover, it exhibited higher concentrations of some aroma esters compared to wine with less SO2, similar to those of wine with typical SO2, as determined by SPME/GC-MS analysis. Wine with typical SO2 exhibited better aroma than the others