The Effects of Heat and Oxidation
In order to store open wine so it stays fresh for a long time, you need to combat the enemies of heat and oxidation. Oxidation is the main culprit, heat just speeds up the process.
Wine in an unopened bottle is exposed to oxygen in minute quantities. This is a benefit to aging wine, but a detriment to wines that are ready-to-drink (already at their peak of drinkability). Once the bottle is open, the flood of oxygen can make a young wine blossom for a short time (by in effect speeding up the aging process), or cause an old one to whither away.
White wines are more susceptible than red wines to heat and oxidation. That’s because red wines contain more tannins which act as antioxidants. Therefore, young, concentrated or tannic, red wines will last longer after opening than mature, light reds, and considerably longer than white wines. But no matter what type of wine, if a bottle has been poured from several times and left open at room temperature for several hours, what’s left may not hold much interest a day later. Each pour exposes more wine to oxygen and mixes more oxygen into the wine, as well as allowing aroma and flavor elements to escape.
Note: Fortified wines, especially Madeiras, Tawny Ports and Sweet Sherries can last several weeks without any special efforts at preservation. Box wines or cask wines, due to their unique packaging, can last 4 to 6 weeks.
Step 1: Stop the Flood of Oxygen
The first step to preserving your wine is to stop oxygen from entering the bottle. A wine bottle stopper is the most basic tool for wine preservation (they make them for sparkling wine bottles and decanters also). You can also try to reinsert the cork but this can be difficult especially if you mangled it while opening the bottle.
Step 2: Store Open Wine in the Refrigerator
Both red and white wines should be refrigerated after they’re opened. Low temperatures slow the oxidation of wine. Refrigerating the wine should be used with any other wine preservation techniques to produce better results.
Step 3: Reduce the Wine’s Exposure to Oxygen in the Bottle
Not only should you stop air from entering the bottle, you should minimize the wine’s exposure to air in the bottle. A simple way to do this is to make sure to store open wine bottles upright (in the refrigerator) to limit the amount of wine surface area exposed to oxygen.
A bottle that’s 1/4 full will have more air than wine and will oxidize much faster than a bottle that’s 3/4 full. So, to minimize the wine’s exposure to oxygen you can transfer the leftover wine to a smaller vessel, for example a half-bottle (a 375 milliliter bottle) if you have one available or a small decanter.
Step 3a: Pump or Squeeze Out the Air
There are now tons of wine products on the market whose purpose is to remove air from wine bottles.
Vacu-Vin
One of the originals was the Vacu-Vin. In place of the cork you use a rubber stopper, then you put the Vacu-Vin on top of it and pump it several times. The basic model is often criticized for requiring too many pumps and having leaky stoppers. The response to this criticism was the Concerto.
The new Vacu-Vin Concerto features a special vacuum indicator that clicks when the maximum vacuum level is reached. The ergonomically-designed pump and tighter stoppers feature a stronger and longer-lasting vacuum. However, a strong vacuum has its drawbacks it tends to suck out the light aromatic molecules and bring Carbon Dioxide (CO2) out of solution, leaving some wines a bit flat and definitely lacking in aroma. Never use this kind of product on a bottle of Champagne.
PlatyPreserve
Nature hates a vacuum, so creating a strong one and maintaining it is very difficult, eventually the air just creeps back in. So how do you remove all that air without pumping 1,000 times? Turns out that you can simply squeeze it out. The problem is the container i.e. the glass bottle. The PlatyPreserve is an airtight reservoir that’s flexible enough to allow you to completely eliminate air from the container by squeezing it out. It’s also made from materials that ensure leak protection and do not transfer a plastic taste to the wine. Think about box or cask wine, that stuff lasts forever. Wine in a box is actually wine in a plastic bag, the box just makes it more marketable. You can buy a single bag ($10) or a set of 4 ($30).
Step 3b: Displace Oxygen with Gas
Using gas or a combination of gases to displace oxygen is a very common winemaking technique, especially among winemakers who prefer more modern reductive (i.e. minimizing the wine’s exposure to oxygen) winemaking techniques. Therefore it should not be surprising that the subject of which gas or combination of gases is most effective has been studied by the wine industry. Nevertheless, vocal proponents of one or another of the most commonly used gases (i.e. either argon, nitrogen, or carbon dioxide) exist causing unending controversy among winemakers and is now a point of contention in the wine preservation industry.
The cause of this controversy is often that most people (including wine professionals) don’t understand the chemistry. Here’s the basics any chemistry teacher should be able to tell you about the gases involved:
| Gas | Nitrogen | Argon | Carbon Dioxide | Oxygen | Air |
|---|---|---|---|---|---|
| Chemical Symbol | N2 | Ar | CO2 | O2 | N2 + O2 + CO2 + Ar |
| Molecular Mass (g/mol) | 28.0134 | 39.948 | 44.01 | 32.0 | 28.97 |
| Density Gas (kg/m3 @ 20°C and 1 atm) | 1.165 | 1.661 | 1.842 | 1.331 | 1.205 |
| Specific Gravity | 0.9669 | 1.38 | 1.528 | 1.10 | 1.0 |
| Solubility in Water of Pure Gas (v/v @ 20°C and 1 atm) | 0.0154 | 0.0337 | 0.878 | 0.031 | 0.0187 |
There are clearly differences between the gases, but are those differences significant?
Multi-Gas Systems
Private Preserve: This is a very popular preservation technique. It’s a can of different gases (a mixture of purified carbon dioxide, nitrogen and argon) that, when sprayed through a long, thin straw into a partially-filled bottle of wine, displaces the oxygen and forms a protective blanket over the wine. You then store open wine upright, thereby minimizing the surface area exposed to oxygen, and place in the refrigerator.
Properly used, Private Preserve can protect a number of different wines for extended periods ranging from a few days to a couple of weeks. Once again, a bottle that is 3/4 full will last longer than one that is 1/4 full. A bottle that was treated soon after opening will last longer than one that was treated after a few hours.
The manufacturer says it’s good for 120 uses. That’s a bit optimistic, but a can does last a long time and compared to other wine accessories, it’s cheap ($10). However, Private Preserve is difficult to apply consistently. It must be sprayed into the bottle for a certain amount of time, at the correct distance and angle to prevent turbulence that can draw in extra air. The cork must be quickly re-inserted without snagging the applicator straw or losing it inside the bottle completely.
Nitrogen-Based Systems
Nitrogen-based wine dispensers are very common, but unlike the above techniques, you’re not trying to save the wine after you’ve enjoyed half the bottle, the wine is served from within the system, minimizing the wine’s exposure to air. Some examples are Winekeeper and Nitrotap. In the case of Nitrotap, a single-bottle wine dispenser (unrefrigerated) costs $100 (nitrogen cylinder must be replaced after 25 uses. A 4-bottle, refrigerated unit from Winekeeper costs $2,000 (Wow!), it’s probably best suited for restaurants. An opened wine bottle lasts 3 weeks.
Winekeeper and Nitrotap are reliable ways to store open wine, if there’s any criticism it’s the use of Nitrogen gas. Argon is 80% more effective than nitrogen because nitrogen is lighter than air and doesn’t have a blanketing effect. Nitrogen also requires a large volume of gas to be effective and therefore costs more. For example, the nitrogen replacement canister for the single-bottle Nitrotap (25 uses) costs $20 compared to $15 for 60 uses for some Argon systems. Another alternative is carbon dioxide which is heavier than air but is also readily absorbed by wine, negating its blanketing effect.
Argon-Based Systems
ArT Wine Preserver: Like Private Preserve above, ArT Wine Preserver is a can of inert gas that is sprayed into a partially-filled bottle of wine for about 2 seconds. A wine stopper is immediately used to seal the bottle,and the bottle is placed upright in the refrigerator. The wine lasts for 7 to 30 days, and you get 40 uses per can. Unlike Private Preserve there’s no long straw to snag, a universal stopper is included with the can (no more re-inserting mangled corks) and of course you’re using superior Argon gas. A kit costs $15.
Coravin: The dream of enjoying wine by the glass without wasting half the bottle if you’re single, or getting drunk so you don’t. The ability to taste multiple bottles of wine in one night with friends if you have a large collection without it costing a lot of money. This is what Coravin promises with its unique wine opener/preservation system.
The Coravin allows you to serve wine without removing the cork, thus avoiding the massive oxidation that comes with opening a wine bottle. A hollow needle is inserted through the cork, the wine bottle is pressurized with Argon gas and the wine is poured out through the needle. The Coravin is then removed and the cork re-seals itself. Coravin claims that wine opened and preserved with its system can last for months or years without negative effects. So you can pull a bottle from your cellar to check its aging progress, pour a glass with the Coravin, then pop it back into the wine rack and check it next year.
However one of the downsides of this system is that you can’t open ALL bottles of wine with it, only bottles with natural cork. Artificial corks or screw caps will not re-seal or will break the needle. Make sure you remove the foil from the bottle to verify the bottle uses natural cork. Old, brittle natural cork may not re-seal either. Another downside is the cost of the system, $210 for the kit which includes 2 Argon capsules (15 uses each). Replacement capsules can be bought at about $18 per 2-pack.
The added cost of using the patented Argon capsules on cheap wine makes cheap wine not so cheap. On a percentage of cost basis, it is better to use the Coravin on premium wines, so the total cost of the wine doesn’t increase significantly. Plus, cheap wines are more likely to use screw caps and artificial corks.
The reason premium wines use natural corks is that they allow minute amounts of oxygen to enter the bottle. This very slow oxidation at the right temperature is the aging process and is the reason why it is doubtful that the Coravin has no effect on an aging bottle of wine. Argon is very effective at blocking oxidation, although not 100%. If argon were 100% effective, using the Coravin would halt the aging process completely. What is the rate at which oxygen enters the bottle through the cork? What is the ratio of oxygen to argon in the bottle, and how does it change as the space in the bottle increases with each serving? The wine may not spoil, but the truth is, it is no longer an accurate reflection of the aging progress in an undisturbed bottle of wine. Nevertheless, Coravin is probably the most effective wine preservation device on the market, preserving wine for months to years. If your pockets are deep enough, go get one.