Premature oxidation is a wine fault where the wine (usually a white wine) has oxidised far more rapidly than you would expect for its age. The wine is typically deeper in colour (a dull, almost murky, yellow) and will possibly have aromas of bruised apples, even tending towards Sherry-like notes. It is most commonly caused by a faulty cork (in the absence of a good seal, more oxygen is allowed into the bottle) or very low sulphur dioxide levels. It can also appear in wines sealed with a screw cap if the cap has been damaged. It was very widely seen in the white wines of Bourgogne in the late 1990s/early 2000s.
