- Ideal Wine Storage Conditions
- Heat and Oxidation
- Ultra-Violet Light
- Possible Wine Storage Locations
Learning how to store wine is first about wine protection, and second as you get more sophisticated, aging wine. Another way to put it is first you must conquer short-term wine storage, then you can attempt long-term wine storage.
Ideal Wine Storage Conditions
If you’ve been into wine for a while, you’ve probably heard about ideal wine storage conditions. This set of optimal environmental conditions should be called “Ideal Long-term Wine Storage Conditions” because for the average person who just needs to protect their wine until they have the time to drink it (maybe a couple of weeks or a month), relative humidity and vibrations don’t play a role, you can even get away with not storing your wine at 55°F. Short-term wine storage is mostly about temperature control and protection against Ultra-Violet light (UV).
Ideal Wine Storage Conditions
- 55°F ambient temperature
- No more than 5 -10°F annual variation in temperature, 1 – 3°F daily variation in temperature
- 70% relative humidity
- No Vibrations
So what’s so special about 55°F? Well technically wine can be stored safely between 40 and 65°F (the range of wine serving temperatures), as long as the temperature remains constant i.e. no more than 1 – 3°F daily variation in temperature. Large temperature variations will ruin your wine. But as you start building your wine collection, aim for 55°F because it’s the best wine aging temperature (for more information see below).
Heat and Oxidation
A completely oxidized wine is a dead wine, however, some oxidation is a natural part of the aging process. When aging wine, an acceptable level of oxidation occurs as wine reacts with the oxygen in the unfilled part of the bottle (ullage), as well as with very small amounts of oxygen that enter through the cork.
White wines are more susceptible than red wines to oxidation. Why? Because red wines contain more tannins which act as antioxidants. So if you like white wines make an extra effort to keep them protected.
How Can You Tell If a Wine is Too Oxidized?
It will taste flat, the exposure to oxygen has taken out some of the volatile chemicals that are responsible for wine’s aroma. After repeated exposure, the color of the wine will begin to change. Red wines will take on a brick-red or even brown hue, whites will darken and take on a golden-brown or amber color.
What Causes Oxidation?
Heat increases the rate at which wine ages or is oxidized. Oxidation is a chemical process and like every chemical process, heat increases its reaction rate. For every 18°F increase in temperature, the aging rate of wine doubles. So, storing wine at room temperature (73°F) cuts its aging potential in half compared to 55°F.
Now this may not seem like a bad thing to some. After all, you can take that Cabernet Sauvignon that’s supposed to age for 10 years and cut its wine storage time in half at room temperature, right? Well, wine is a complex mix of amino acids, phenols, carbohydrates and other components that ordinarily are imperceptible to human senses. At about 70°F the reactions of these components accelerate to the point that they can be detected in the wine, causing off tastes and aromas.
At temperatures above 80°F, wine is in danger of being cooked. How can you tell if a wine is cooked? It may smell of burnt sugar or stewed fruit instead of having vibrant fruit flavors and aromas. A slightly cooked wine may have dull aromas and flavors. High temperatures or temperature spikes can also cause wine-bottle corks to protrude from the bottle neck, breaking the cork’s seal and exposing the wine to too much oxygen.
Note: Heat damage can occur very quickly and heat damaged wine should be consumed immediately, hopefully within 24hrs. It may still be palatable, but the longer you wait, the worse it gets. The wine cellar is not a hospital, wine faults get worse with age.
At the other end of the spectrum, wines at temperatures below 50°F barely age at all. So, if you want to consume your age-worthy wines within a reasonable period of time, long-term wine storage at these temperatures is not recommended. Also at low temperatures tartaric acid crystals may develop in the wine. They’re harmless, but unpleasant to see and taste.
So, 55°F is a nice middle temperature that allows aging to occur at a slow enough rate that it becomes more nuanced and complex but doesn’t produce off aromas and tastes.
The most damaging way that wine is oxidized is through temperature fluctuations (i.e. variations in temperature in excess of 1 – 3°F daily). As a wine heats up it expands, putting pressure on the cork. As it cools down it contracts, creating a pressure differential which pulls air into the bottle. The more frequent the fluctuations, and the wider the temperature swings, the greater the wine’s exposure to air. Eventually wine will begin to seep past the cork once the integrity of the seal is compromised, resulting in increased ullage (i.e. less wine and more air in the bottle) and in the end you’ll be left with half a bottle of oxidized wine.
Lightstruck (or gouts de lumiere – French for tastes of light) is a term used to describe wines that have had excessive exposure to sunlight or fluorescent light (technically ultraviolet light in the wavelength of 325 to 450 nm). Delicate wines, like white and sparkling wines are the most likely to be affected, with the fault causing a wet-cardboard or wet-wool flavor and aroma (this phenomenon also affects beer, but causes a skunk smell). However, red wines rarely become lightstruck because the polyphenols (tannins) present in the wine protect it.
The wine industry recognizes the need to protect wine from UV light, which is why they put wine in colored-glass bottles. However, the typical green-glass wine-bottle while offering some protection is not sufficient to block all the offending radiation (see study which points out that UV damage can occur in a matter of hours). That’s why it’s necessary to limit your wine’s exposure to sunlight and fluorescent light, or simply keep the wine storage area dark.
The discussion above clearly illustrates the importance of protecting the cork seal. When you’re first learning how to store wine, inevitably someone tells you that wine storage is simply a matter of laying wine bottles on their side to keep the corks moist and elastic. Not only is this far from the truth, but this technique only keeps the cork moist on the inside of the bottle.
To prevent the top of the cork from drying out, shrinking and cracking, the wine storage area needs at least 50% relative humidity, 70% creates a more effective cork seal, particularly important if you have an expensive wine collection. Above 80%, mold is likely to form on the cork and label. This is primarily a cosmetic problem, but if you intend to sell your wine, have a large wine collection (since you need to be able to identify the bottle) or like to collect labels, keeping the label pristine is very important.
To protect your wine labels, you can wrap the wine bottles with saran (plastic) wrap.
The jury is still out regarding the effects of vibration on wine. Vibrations may affect flavor and bouquet, but there have been no studies done that conclude that it’s detrimental to aging or protecting wines.
A study was conducted on the subject in 1962. It was done by Dr. Vernon L. Singleton Professor of Enology, Emeritus from the University of California at Davis and was titled Aging of Wines and Other Spirituous Products Accelerated by Physical Treatments. In that study, Dr. Singleton performed experiments to test the effects of vibration on wine maturation. The results are discussed in Matt Kramer’s book Making Sense of Wine (revised edition). Dr. Singleton is quoted as follows:
The only bad feature about vibration is possibly in dispersing sediments. You may, if you disperse them hard enough and often enough, find that it produces such fine particles that it fails to settle. So it may affect clarity, which in turn, can affect flavor. But barring that, I can say that vibration doesn’t make a difference. If you can look at a bottle of wine and it’s still clear, then it wasn’t vibrated enough to make a difference.
Therefore, following the traditional procedure of standing old red wine bottles up and letting the bitter sediment settle for a few days before serving should be sufficient to counteract this negative influence.
Note: Most wines are ready-to-drink and do not require aging and therefore rarely have sediment that can be stirred up by vibrations.
Possible Wine Storage Locations
Storing Wine in Kitchens, Garages and Storage Sheds
Without any kind of specialized equipment or modifications, the kitchen, garage and storage sheds are the worst places to keep your wine. The kitchen is one of the hottest places in the house, it also tends to be very well lit. It is subject to temperature fluctuations every time the stove or oven is being used and it contains lots of appliances that emit heat and vibrations.
Garages and storage sheds are rarely temperature controlled, so they tend to be very hot in summer, and very cold in winter. These places are generally not very clean, they may smell musty and have rodents that can chew wine packaging, corks and labels (not good if you want to sell your wine). They also tend to contain strong smelling substances like gasoline, solvents, paint and cleaning solutions whose odors can work their way into the wine through the cork.
Storing Wine in the Basement
Most people know that the basement is the ideal place to store their wine. It’s usually cool, dark and damp, but don’t take these conditions for granted. If your basement is not completely underground, store your wines against a subterranean wall. Measure the temperature, humidity and temperature fluctuations so you know the conditions you’re dealing with (see below).
Make sure the basement is clean and free of strong-smelling odors. If the basement is particularly damp, don’t keep the wine stacked on the floor, especially if it’s in cardboard boxes. You should consider building or buying a wine rack system.
Wine racks can be bought prefabricated or as low-cost, do-it-yourself kits. Materials usually consist of stainless steel, wire grids or wood. Although stainless steel and wire grids are cheap, they are the least desirable because they tend to bend under the weight of the bottle, rust in humid conditions unless treated, and cause hot or cold spots through heat conduction.
Redwood is the best wine rack material because it’s naturally odor-free, doesn’t require staining or finishing (eliminating chemical off-gassing that might harm the wine), resists rot and mildew, and is strong relative to it’s weight so it doesn’t bend easily.
Softwoods such as Pine and Douglas fir are more prone to warping under moist conditions (unless sealed). But, they are good, low-cost options, mainly because they’re easier to work with and lighter to ship than hardwoods.
Storing Wine in Closets and Other Indoor Spaces
What do you do if you don’t have a basement? This is a popular question with newbies just learning how to store wine. First, look for closets, or other storage spaces in the interior of the house or apartment (i.e. away from exterior walls so they stay cool). Closets or storage spaces under stairs usually work well. If you can’t find an interior space, choose one against a shaded or northern wall.
Second, you’re going to have to measure the conditions of the location you plan to use to store wine. One of the most important tools you can own for this purpose is a thermometer / hygrometer which measures and records max / min temperatures and relative humidity. They’re not expensive, and they’re indispensable. If it comes down to a choice between a space with a higher but stable temperature, and one with cooler but fluctuating temperature, choose the one with the higher but stable temperature.
How do you protect and organize your wine in such small confines? Modular plastic containers work well. Storvino makes wine storage containers of recycled polyethylene. They’re cheap, light, expandable, don’t warp and don’t require carpentry skills.
Another useful tool is the polystyrene (styrofoam) wine box. If you order wine online or if wine has ever been shipped to you, you probably know what it is and may even have a few stashed away somewhere. They’re great for minimizing the effects of temperature fluctuations. If you don’t have any lying around, you can order them from shipping companies like Uline.
Wine bottle sizes like Magnums and Jeroboams are less susceptible to temperature fluctuations. The larger volume of liquid in a big wine bottle takes longer to warm up or cool down, making the temperature fluctuations smaller and less frequent. So, if you can afford to buy large-format wine bottles, they hold up better than standard bottles in less-than-ideal conditions.
Storing wine under these conditions is a short-term solution. You should not store wine longer than 6 months at room temperature.
Storing Wine in the Refrigerator
Refrigerators are great at preserving perishables for short periods of time. They are not meant for long-term wine storage. Don’t confuse preservation of an unfinished bottle of wine (for a few days or a week) with aging wine. Refrigerators are simply too cold, they maintain temperatures of 40°F or less, and as mentioned above, very little if any aging occurs at these temperatures.
Refrigerators do not maintain a constant temperature. The heart of the refrigerator’s cooling system is the compressor. The compressor cycles on and off based on the temperature setting of the thermostat in the refrigerator. The thermostat only establishes the setpoint, but the actual temperature can vary by several degrees above or below the setpoint.
Temperature varies because once the setpoint temperature is achieved, the compressor switches off, and depending on the system will come back on after the temperature has warmed 3 to 5°F. This doesn’t occur daily, this temperature fluctuation occurs every cycle (every half hour?). This is done to preserve energy and to prevent the compressor from burning out by constantly turning on and off. Temperature fluctuations can also be caused by automatic defrosting cycles in frost-free refrigerators and constantly opening the refrigerator door.
Refrigerators are also very low in humidity. Depending on the system, relative humidity can vary between 17 and 40%. At the low end are refrigerators that share air with a freezer, which strips humidity from the air. At the high end are systems where the refrigerator and freezer are isolated from each other, or refrigerators with no freezer.
You also don’t want to store your wine with food, especially food with strong odors (i.e. onions, garlic). You can bet that in the small confines of a refrigerator, these odors will work their way into the wine through the cork (making your wine taste like the strong smelling offender). You should also keep wine away from fermented foods or foods likely to ferment (i.e. cheese, fruit, vegetables), anything with its own yeasts can wreak havoc with a wine’s development.
How to Store Wine Using a Modified Refrigerator
A spare refrigerator makes a better wine storage location than the refrigerator you use everyday to store food (especially if you increase its operating temperature). If you use it exclusively for storing wine you can reduce the temperature fluctuations by filling the refrigerator completely with wine or, filling empty space with bottles of water. This is a cooling block and will retain temperature much better than the surrounding air. Using a spare refrigerator also means you are less likely to cause temperature fluctuations by constantly opening the door.
There is a piece of equipment used by homemade-beer brewers that has been adopted by wine enthusiasts to control temperature in a refrigerator or freezer. These temperature controllers (both digital and analog controllers available) by Johnson Controls, Ranco and Kegworks for example, can be used to maintain the refrigerator or freezer’s temperature at optimum for wine aging (55°F) or at any wine serving temperature (40 to 65°F). Digital controllers can maintain temperature within + / – 1°F. The equipment is easy to use if you buy it pre-wired, you simply plug the controller into an outlet, and plug the refrigerator into the controller.
Using this equipment on a spare refrigerator and packing it tightly with wine or water bottles, should control temperature satisfactorily for short-term wine storage. However, using a temperature controller on your refrigerator can possibly shorten the life of your compressor. In addition, you have to increase the relative humidity inside the refrigerator if you want to store wine for more than a year. Putting a bowl of water inside may help, but the results will probably be erratic (this should be monitored with a thermometer / hygrometer, see above).
If you don’t have a spare refrigerator, a wine refrigerator or cooler is an acceptable short-term solution (less than a year). The problems of a wine refrigerator are essentially the same as a regular refrigerator except it normally operates at warmer temperatures and doesn’t have to be forced. Its primary purpose is to keep wine at proper serving temperatures, not age wine for ten years.
For long-term storage (or aging wine) you should consider buying a an electric wine cellar or wine storage cabinet. They’re designed to maintain ideal wine storage conditions, but are considerably more expensive than a wine refrigerator.