With some wines, you can recork a 1/2 finished bottle, put it in the fridge, take it out 2 days later, bring it back to serving temperature, and it still tastes fine.
Other wines, like the 2003 Muscadet I tried last weekend, fall apart after a day. You uncork the 1/2 bottle and it smells and tastes tart, like much of the fruit has turned to vinegar.
My question is, what exactly is going on in the wine? Is it a subtractive or additive process (meaning, is it a matter of the wine losing positive aromas/flavors, or gaining negative ones)?
Also, what components in the wine make it more, or less, susceptible to turning vinegary with exposure to air?