Oxidation
A wine fault (or intentional style) caused by excess exposure to oxygen, producing stale, flat, brown-apple, or nutty aromas and a loss of fresh fruit character.
In depth
Oxidation occurs when wine reacts with oxygen in an uncontrolled way. Oxygen causes phenolic compounds to oxidise, producing brown colours in whites and brick-orange hues in reds, and generating off-aromas including: stale apple (acetaldehyde), sherry-like nuttiness, flat or cardboard notes, and an overall loss of the wine's primary fruit character.
Oxidation can be prevented through: the use of sulphur dioxide (SO₂) as an antioxidant, minimising headspace in tanks and barrels, careful filling and sealing of bottles, and avoiding excessive pumping and splashing during transfers.
However, controlled oxidation is intentionally used for certain wine styles. Sherry production uses deliberate oxidation (Oloroso Sherry is fully oxidatively aged). Madeira's distinctive character comes from intentional oxidative ageing under heat. Some Rhône whites (like white Hermitage from Marsanne) develop an intentional oxidative, waxy character with age.
At Level 3, candidates must distinguish between: unintentional oxidation (a fault), intentional oxidative ageing (a style), and micro-oxygenation (a controlled winemaking technique).
Related exam topics
Frequently asked questions
- How can you tell if a wine is oxidised?
- Oxidised white wine looks brown or amber (past its golden colour), smells flat or stale — sometimes like bruised apple, cardboard, or sherry — and has lost its fresh fruit aromas. Oxidised red wine has orange-brick tinges at the rim and a flat, nutty smell. The wine tastes hollow and lifeless. Compare this to deliberate oxidative styles (Oloroso Sherry, Tawny Port) where the nutty, dried-fruit character is intentional and appealing.
Practise questions on this topic
Use Vinlecta to practise exam-style questions that test your knowledge of oxidation and related topics.