Oxygen in wines

CasteUari, M., Simonato, B., TomielU, G. B., SpineUi, P., and Ferrarini, R. (2004). Effects of different enological treatments on dissolved oxygen in wines. Ital. ]. Food Sci. 16,387-396. 

Removal of trace levels of oxygen. Traces of oxygen in wines and fruit juices cause discolouration and/or oxidation of ascorbic acid. Chemical... 

GLC, atomic absorption and mass spectrophotometry, enzymatic, and specific colorimetric procedures seem to be the likely candidates for routine use in the future. Automation will certainly be common. GLC is now used to detect imitation muscat wines (127). Characteristic flavor byproducts of yeasts may be detected and measured. Multiple correlation of the amounts of the more influential major and minor constituents with wine quality is the goal of such research. A simple apparatus for the simultaneous determination of the redox potential (two platinum electrodes), pH, specific conductivity, oxygen, and carbon dioxide (ion-specific electrode) has been devised (128). Molecular oxygen in wines has been determined by several procedures—polarography (129) and GLC being the latest. 

The evolution of color may be affected by the characteristics of the oxidative process, that is, the barrel which has been used. Oak barrels are porous recipients that allow oxygen to enter continuously. The dissolved oxygen in wines matured in new barrels is higher than in used barrels because prolonged use causes a progressive colmatation of wood pores and a consequent decrease in the wine oxygen content. After the barrel has been used three to five times, the quantity of dissolved oxygen in wines will be very close to that of wines stored in tanks, so different wine color characteristics will be obtained (6). 

Oxidation is another important factor for the wine-aging process. Major oxidation reactions taking place in wine following oxygen exposure actually involve other wine constituents that are primarily ethanol and, in the presence of metal ions, tartaric acid rather than flavonoids, although phenolic compounds have been shown to participate in oxidation of ethanol to acetaldehyde. ... 

The impact of oxygen on wine aroma is likely to involve several oxidation mechanisms. One pathway involves pol) henol quinones, particularly in the case of the removal of unwanted sulfur-containing off-odors (RSH Mestres et ah, 2000), as illustrated in Fig. 4.4A. 

The impact of MOX upon reductive odors was included in the study of McCord (2003) for MOX at 5-10 mL/L/month over 5 months on a Cabernet Sauvignon wine in commercial scale tanks. Lower concentrations of methyl mercaptan and ethyl mercaptan were observed in the oxygenated wines, but no impact was seen upon disulfides, in spite of the suggestion that concentrations of the disulfides could increase due to direct oxidation of sulfides. Dimethyl sulfide concentrations were not affected, except that lower concentrations were seen in wines with added toasted oak staves or segments, with or without MOX. The concentrations of various oak extracted compounds were also measured in this study, with similar levels seen with and without MOX alongside appreciable increases due to the presence of the oak staves or segments in some cases (e.g., lactones and vanillin), oxygenation appeared to enhance aroma extraction. 

Danilewicz, J. C. (2003). Review of reaction mechanisms of oxygen and proposed intermediate reduction products in wine Central role of iron and copper. Am. J. Enol. Vitic. 54, 73-85. 

Devatine, A., Chiciuc, 1., Poupot, C., and Mietton-Peuchot, M. (2007). Micro-oxygenation of wine in presence of dissolved carbon dioxide. Chem. Eng. Sci. 62, 4579-4588. 

Hernandez-Orte, P., Lapena, A. C., Escudero, A., Astrain, J., Baron, C., Pardo, 1., Polo, L., Ferrer, S., Cacho, J., and Ferreira, V. (2009). Effect of micro-oxygenation on the evolution of aromatic compounds in wines Malolactic fermentation and ageing in wood. LWT— Food Sci. Technol. 42, 391 01. 

Kelly, M. and Wollan, D. (2003). Micro-oxygenation of wine in barrels. Aust. NZ Grapegrow. Winentak. Annu. Tech. Issue 473a, 29-32. 

Figure 1. Flavonoid content mg/liter GAE, in wines made from the same grapes, as correlated with browning of each wine upon exposure to oxygen under standardized conditions...

A very important lactone in wines is the so-called wine lactone," 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone 5, which exists in four enantiomeric pairs. This compound was first identified and isolated from the urine of Koala bears (75TL1885, 97JAFC3027), from their diet of the leaves of the Eucalyptus punctata tree. And this shows that the wine lactone belongs to monoterpenoid flavoring ingredients, which have been converted into oxygenated forms. 

---