I used to make wine, just a backyard vintner, but know quite a bit about it.
Wine is mostly alcohol, water, flavoids, and some acid. Not much can happen to the stuff actually. Air can allow some bacteria to grow, but so can the absence of air. So, some wine just goes bad in the bottle. To prevent that from happening, sulfer is typically added to the wine. This doesn't escape when you open the bottle.
There is some air in there when it is bottled. When you pull the cork, new air gets in, but not very much. It will indeed cause some changes to the flavor compounds in the wine. With old red wine, people usually want that a bit. i.e. let it breathe. But with white, there are not as much flavor compounds to deal with. The water, alcohol, and acid usually are pretty stable.
So, if you are drinking really good wine, and have a very astute taste, then you might be able to tell that it had been open a week. (of course you could never drink mine since it was not that good) But if you drink the usual cheaper stuff like I do, you can leave it recorked in the refrigerator for a long time and it will be about the same as when you opened it.
It is best if you don't leave one inch in the bottom of the bottle full of air. This is way to much air to the volume of wine. But if the bottle is somewhere near half full, you will be able to keep it weeks. I have.
And nothing will actually happen to it. Vinagar is made without air and will not form with too much oxygen. So, it doesn't spoil like milk, or go flat like soda, or even absorb flavors like water.
But I do say that you should just find a reason to drink the rest of the bottle, why keep the stuff for very long?
Have a good day
- Response by welloone
, A Mr. Married Guy, Male, 66 or older, Retired