On average, a properly stored bottle of wine loses its optimal taste and richness within about three days to a week after opening. Lighter wines with fewer tannins, such as a Pinot noir, are even more short-lived. There are numerous environmental threats to an opened bottle of vino, but the two most pervasive are over-exposure to air, which leads to oxidation, and bacteria that can cause other forms of spoilage. In short, unless you do something to preserve a favorite wine (such as committing it to memory by drinking the whole bottle at once), that fine Merlot basically begins turning to vinegar within a matter of days. Here are three ways to help preserve the character of your favorite label for much longer.