Oxidation
Oxidation
Oxidation in wine refers to the chemical reactions that occur when oxygen interacts with components of the must or finished wine. These processes can significantly influence aroma, flavour, colour, and overall stability of the wine. While controlled oxidation plays a role in desirable wine styles, excessive or unintended oxidation is generally considered a fault.
Chemical processes
Oxidation involves the interaction of phenolic compounds, ethanol, and other constituents with oxygen. These reactions often lead to the formation of acetaldehyde, quinones, and brown pigments, contributing to colour changes and flavour shifts in the wine.[1] The susceptibility of wine to oxidation depends on grape variety, vinification practices, and levels of protective compounds such as sulphur dioxide.[2]
Winemaking impact
Oxidation can occur at multiple stages of winemaking. During fermentation and maturation, controlled oxygen exposure may enhance complexity, soften tannins, and stabilise colour. Techniques such as barrel ageing deliberately utilise micro-oxygenation. Conversely, excessive exposure during racking, bottling, or storage can cause browning, loss of fruit character, and undesirable aromas.[3]
Oxidative wine styles
Certain traditional wine styles rely on oxidation as a key element of their character. Examples include Sherry, Madeira, Vin Jaune from Jura, and Tawny Port. These wines develop nutty, caramelised, and rancio notes associated with controlled oxidative ageing.[4]
Prevention and management
To prevent unwanted oxidation, winemakers commonly use antioxidants such as sulphur dioxide, maintain topped-up vessels to minimise oxygen exposure, and control temperature during storage. Advances in closures and bottling technology also help mitigate the risk of oxidative spoilage.
See also
References
- ↑ Ribéreau-Gayon et al., Handbook of Enology, Vol. 2, Wiley, 2006, oxidative processes. ISBN 978-0470010396.
- ↑ Jackson, Wine Science, 5th ed., 2020, oxidation & browning. ISBN 978-0128161180.
- ↑ Robinson (ed.), The Oxford Companion to Wine (entry: oxidation), 2015. ISBN 978-0198705383.
- ↑ AWRI, “Oxidation and reduction in wine”, https://www.awri.com.au