Decrease of Wine Volatile Aroma Esters by Oxidation

The effect of oxidation on the levels of wine volatile aroma esters was studied. Chardonnay wine wasbottled either in the presence of nitrogen or air in the headspace. Moreover, Fe II was added to the wineand the bottles were closed in the presence of air. Absorbance values were recorded at 420 nm (browningindex), while volatile esters were evaluated during storage using SPME/GC-MS. During wine storage ofup to nine months, wines bottled in the presence of air exhibited higher browning indexes and lowerlevels of several esters, such ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate and ethyldecanoate, in comparison to wines bottled under nitrogen. Addition of Fe II led to higher browning indexesand lower levels of several esters during wine storage. In addition, Fe II was added along with H2O2 toChardonnay wine and the bottles were closed in the presence of air. These additions led to wines withhigher browning indexes and lower levels of several esters during wine storage up to 40 days. The presentresults demonstrate that wine volatile aroma esters can be decreased by oxidation under semi-oxidativeand forced oxidative conditions. As a result, oxidation should be taken into account in the decrease ofaroma esters during wine storage

Protection of Aroma Volatiles in a Red Wine with Low Sulphur Dioxide by a Mixture of Glutathione, Caffeic Acid and Gallic Acid

The levels of several esters and other volatiles in Merlot-Cabernet Sauvignon blend red wines with typicalsulphur dioxide (35 mg/L), with low sulphur dioxide (25 mg/L), and with low sulphur dioxide (25 mg/L)plus a mixture of antioxidants (glutathione 20 mg/L, caffeic acid 60 mg/L and gallic acid 20 mg/L), wereevaluated at bottling, and after 18 and 36 months of ageing. Most volatiles decreased during wine storage.At bottling and after 18 months of storage, all three wines exhibited similar levels of volatiles. After 36months of storage, wines with low sulphur dioxide exhibited lower levels of many volatiles, such as ethylacetate, ethyl hexanoate, ethyl octanoate and 2-phenylethanol. On the other hand, wines with low sulphurdioxide plus the mixture of antioxidants exhibited similar levels of most volatiles in comparison with wineswith typical sulphur dioxide. The present results indicate that a mixture of glutathione, caffeic acid andgallic acid can protect esters and other volatiles in young red wine with low sulphur dioxide, and canreplace part of sulphur dioxide typically used

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