The moment you pull that cork, wine comes in contact with air. And once that happens, the oxidation process begins. If youre not planning on consuming all the wine in one sitting, you need to know how to store the remaining wine so it wont go bad.

Oxidation is the chemical reaction that occurs when oxygen comes in contact with wine. At first, oxidation is a good thing; it helps open up the wine, revealing different facets of its bouquet and aroma. However, after a couple of hours, further oxidation is a bad thing. It starts to damage the wine and will eventually ruin it.

Many of us have had the experience of leaving an unfinished bottle out all night without the cork back on. The difference in flavor and aroma the next day is striking and unmistakable. Even if re-corked the next day, the wine will usually taste flat, raisiny, and unpleasant -- all a product of the oxidation process.

So how do you preserve an open bottle of wine when you dont want to (or cant) drink the whole thing in one sitting? There are only four reliable methods of preserving the remaining wine, some more reliable than others:

1. First, put the cork back on and put the wine in the fridge. The oxidative process slows down dramatically in cooler temperatures. This is a very easy -- and a fairly reliable -- method when you dont have any other choices. Certainly much better than leaving an open bottle on the kitchen counter overnight.

2. A second option is to transfer the remaining wine to a half-bottle (375ml) and put it in the fridge. Doing this eliminates most of the air that would normally come in contact with the wine in a standard-size bottle (750ml). While more effective that method #1, this involves carefully transferring the wine over, which is only practical to do with a funnel.

3. A third alternative is to pump out the air in the bottle with a wine pump. You can get a wine pump virtually anywhere these days, even in stores such as Target, Bed Bath and Beyond, and Linens and Things. These pumps are fairly reliable, but Ive found they work best if you also stick the bottle in the refrigerator after pumping out the air (no pump can completely remove the air from the bottle). Otherwise, youll still notice a slight difference in taste the next day, and a more pronounced difference the following day and beyond.

4. Use a wine preserver spray. This, by far, is the most effective and dependable method of keeping wine fresh. While these sprays cost about $10 a bottle, they are extremely reliable and effective. In my opinion, this is the only way to store opened wine. The spray is actually a blend of harmless inert gasses (gasses that dont react with wine), which keep the wine from spoiling. Spraying the inside the bottle displaces the oxygen already present and leaves a blanket of inert gas over the wine. The amazing thing is, the gas will preserve the wine for days, even weeks! Try a can and see for yourself. Look for them at many local wine shops and online by searching for brands such as Private Preserve.

What about wine thats already spoiled? Whatever you do, dont dump it down the drain. Instead, keep it in the fridge (with a cork on) for recipes that call for a little wine. I always keep a bottle of spoiled wine in the fridge for this purpose. And when a sauce calls for a little wine, I dont have to use the good stuff.

Another idea is to pour it in ice trays and freeze it. And again, when you have a recipe that calls for wine, break off a few wine cubes instead.

Some may argue that its best to use fresh wine when cooking. I say do what youd like. But in my house we never waste a drop of wine!