Oxidation is wine's exposure to oxygen, causing chemical changes that alter colour, flavour, and aroma. Beneficial oxidation occurs slowly during barrel aging, adding complexity and softening tannins. Harmful oxidation (overexposure to oxygen) occurs through poor cork seals, excessive headspace, or heat exposure, turning wine brown, flat, and vinegary. A corked or cooked bottle shows oxidative faults. Young wines are vulnerable to excessive oxidation; some wines (sherry, madeira, tawny port) are intentionally heavily oxidized. Understanding oxidation is critical to proper wine storage and identifying faulty bottles.
WHY IT MATTERS FOR COLLECTORS
Proper storage minimises unwanted oxidation; cork quality and bottle position are critical. Wines showing oxidative faults (brown colour, vinegary aromas) should be rejected. However, some age-worthy wines show graceful oxidative aging over decades.
Tasting cues
- Unwanted oxidation: sherry-like acetaldehyde, browned colour, flat fruit.
- Intentional oxidative styles (some Sherry, Vin Jaune, certain whites) build nutty complexity on purpose.
- Early signs: loss of freshness, bruised apple, dull edges.
Examples
- A forgotten open bottle left on the counter for days will oxidise.
- Poor cork seal or warm storage accelerates oxidative ageing in sealed bottles.
- Madeira is baked and oxidised by design — a different category of “oxidative.”
Cellar actions
- Finish or preserve opened bottles (fridge, inert gas, Coravin for still wine under cork).
- Inspect ullage and seepage on mature purchases — oxidation risk rises with air exposure.
Related terms
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