It seems that every day I have one or two customers come into the store and ask me about the best way to keep leftover wine fresh. Lately there's been a bit of publicity about which system of wine preservation is best, and although the information is generally accurate, the advertising often fails to include all the options and factors.

It goes without saying that the easiest way to prevent wasting wine is to consume it all in one sitting. If a regular size bottle (750 ml) is too much for one meal, consider purchasing half bottles (375 ml). Many wines come in half-bottle size, and generally they are half the price of a regular-sized bottle. But in the event you find yourself (as I often do) with a bit of wine that you want to keep fresh for the next meal, there are several things to take into consideration.

For starters, different types of wine (cabernet, chardonnay, pinot noir) have different life expectancies. Generally speaking a tannic or young cabernet will do quite nicely overnight without any more fuss than putting the cork back in the bottle and keeping it in a cool spot. In fact, many cabs and cab blends will improve from one day to the next. Pinot noir, on the other hand, is fairly fragile and often will not last overnight without some assistance. White wines kept in the fridge will last several days. Young vintage port wines can last weeks. Although it is difficult to make broad generalizations, a rule of thumb is that the more tannic a wine is, the longer it will last after it is opened. You should expect a cabernet, merlot, petite sirah, shiraz, zinfandel or similar wine to last two to three days, a chardonnay, sauvignon blanc or other similar white to last four to five days in the fridge and lighter reds like pinot noir and syrah to last a day or two at best without any help.

You might want to try this experiment. Open a decent bottle of cabernet or merlot and taste it every night for several days. Note your findings from day to day over a week's time. You'll notice the flavors and emphasis of the wine will change over time. This will give you an idea of how a wine will age and how well leftovers will last. At the end of the week you'll probably notice that the wine is flat, having lost most of its fruit flavors and tannins. You know it's wine, but it's not very tasty.

Second, you need to know that the number one enemy of wine is oxygen. Keep the wine away from air and you will double the life expectancy of your leftovers. There are three common methods for keeping wine fresh, and although there are folks who claim that one method is better than another, they all seem to work equally well for me.

Remove the air in the bottle. You can accomplish this by using a vacuum pump system. There are many such systems on the market, and they range in price from $10 to $15 for a vacuum pump and one or two stoppers. The process is simple—just replace the original cork with a rubber stopper, place the vacuum pump over it and pull the air out.

The most common downfall of this method is that the stoppers will become worn over time and lose their ability to seal properly. If you don't get that sucking sound when you take the stopper out of the bottle, you know that the seal is gone and you need to get a new stopper.

Another popular method is to replace the air in the wine bottle with an inert gas. Many restaurants and wine professionals use an inert gas combination of argon, carbon dioxide and nitrogen to replace the air in the wine bottle. You can pick up a can of this handy stuff at most wine shops for under $10, and it will last for about 100 uses. You spray the gas into the wine bottle and it displaces the air and preserves the wine. The challenge with this method is that you must follow the directions closely or it's ineffective.

A cheap alternative to the above methods is to use progressively smaller bottles. Since the concept is reducing or eliminating contact with air, if you pour your leftover wine into a smaller wine bottle you effectively minimize the contact with air. Next time you drink a half bottle (375ml) or smaller bottle, keep it for wine storage. Simply recork the wine and keep it in a cool, dark place.

Regardless of which method you use to keep your leftover wine fresh, it is very important that you always keep your wine in a cool place and away from direct sun.

The bottom line on whether to drink leftover wine is a matter of your personal taste. If the wine tastes lifeless, toss it or use it in a pasta sauce. Or try what some winemakers do: Blend your leftover wines together and discover a new taste sensation!

Buying guide

Private Preserve (100-120 uses per canister), $9.95

Argon, carbon dioxide, nitrogen preservation Vacu-vin pump with one stopper, $10.95—Replacement stoppers, 2 for $4.95

EpiVac Wine Saver pump and two stoppers, $9.95—Replacement stoppers, 2 for $4.95

These products are generally available at fine wine and kitchen supply stores.

Cara Finn is the owner of The Grapevine, a fine wine and cheese store and tasting bar. She can be reached at 408.293.7574 or at info@grapevine-wg.com.