Keeping Wine Fine With Refrigeration
The popularity of wine continues to grow as is evident by the wide varieties, the greater availability, and the increasing number of arguments over what constitutes a really fine wine. At the same time, the storage of wine is not the simple process of sticking the bottles in a cool basement until it is time to uncork one.
Refrigeration is playing a greater and greater role, not only in keeping wine at just the right temperature, but also in giving it a long shelf life.
In fact, refrigeration is vital not only in storage, but on the front end in the winemaking process, and once a bottle is uncorked.
IN STORAGE“Wine ages gracefully when the temperature is consistent and avoids daily and seasonal fluctuations,” said Todd Lowry, refrigeration manager at Wine Cellar Innovations of Cincinnati, Ohio, which designs and installs wine cellars and rack systems. “Refrigeration controls the climate.”
Lawry said the ideal storage temperature is 55°F with a relative humidity (rh) of up to 70 percent. That rh, he said, may seem high to some service technicians but it is designed to be high enough to maintain the integrity of the corks in wine bottles while low enough to avoid damage to a cellar’s insulation due to mold or mildew, or softening of the bottle labels.
The numbers are actually based on the fact that wine storage began in underground caves in Europe. The caves provided consistent storage conditions. As a result, those conditions became the standard for modern wine cellars that need modern refrigeration.
Lowry noted the industry uses basic commercial refrigeration equipment with some modifications. For example, he said the wine industry often opts for units that cool without having to go into defrost, using evaporators that are not so cold that they remove humidity, and cooling with a coil that is as warm as possible.
Variations in temperature and humidity affect wine. Wine Cellar Innovations said wine breathes through the cork and ages in the process. Environmental changes such as fluctuations in wine cellar temperature and humidity accelerate or disrupt the aging process.
“Excessive oxidation causes the wine to become bitter, as it would in a glass overnight,” the company said. “Wine requires oxidation to mature. But it must be regulated to ensure adverse conditions do not affect the aging. The pace of breathing is faster at high temperatures and slower at low temperatures.”
There are also daily changes. “As the temperature rises, the bottle of wine expands,” said the company. “But the wine expands seven times more than the glass bottle. This process creates pressure that can force the wine out of the bottle.
“Then when the bottle cools, a vacuum forms, which sucks oxygen rich air into the bottle. Ullage is the oxygen free air within the bottle. Unregulated wine cellar temperature fluctuations prematurely age and deteriorate the wine.”
While the aesthetics of a cellar can be elaborate, the refrigeration systems are fairly basic.
For example, Wine Cellar’s Winezone split air handler is located outside the wine cellar and the supply and return air is ducted to and from the wine cellar. The wine refrigeration unit looks like a central air conditioning system and comes with electronic controls and digital displays.
Its Waterfall refrigeration system provides cascading water that is an aesthetic touch but also adds humidity below the desired level of evaporation and extracts humidity above the desired level of condensation.
And just like conventional refrigeration systems, the products offered by Wine Cellar include sound blankets for the condensers, and coated evaporator coils for locations in corrosive environments.
Lowry said technicians familiar with refrigeration would be able to deal with the technology needed for the wine industry. “The pressures on the gauges may be a little different, and the humidity and dehumidification control is a bit different,” he said. “But beyond that, the technician will find equipment very similar to that used on a walk-in.”
OPEN UPOnce a wine bottle is opened, wine makers and industry experts suggest the wine be drunk at that time. However, if it is going to be stored after opening, the user should do more than stick the cork back in and put the bottle in the refrigerator.
In fact, Napa Technology of Santa Clara, Calif., has come up with what it calls WineStation®, billed as the world’s first “automated measured dispensing and preservation solution” for businesses such as restaurants, hotels, and concession operators who may have several open bottles of wine.
The ideal situation, said Jeffrey Brooks, managing director of Napa Technology, is to expel the air from a full or partially empty bottle and replace it with food grade argon or nitrogen gas. “This ensures the taste, bouquet and complexity of the wine for up to 90 days after it is open,” he said.
When it comes to temperature control, he said, WineStation was designed to maintain the bottles of wine at the same temperature found in the wine cellars where original barrels of wine are crafted, that of about 65° to 68°, said Brooks.
“We want to optimize the temperature the same as the wine makers who made the wine.”
Each of the company’s Wine Station dispensing systems has a thermocouple-cooling unit “that operates on the same principle as a heat pump in taking heat out and bringing cooling in.”
The company said the modular and expandable design can hold anywhere from four to hundreds of bottles of wine.
IN THE FIELDThe images of the humble, elderly wine grower lovingly looking at grapes or, on a more surreal level, Lucy Ricardo gleefully stomping barefoot on grapes in a huge vat are hardly the reality of most of the wine gathering and making methods today. Refrigeration and other technologies familiar to those in the HVACR industry are more vital than ever.
In the wine making process, those in that industry say refrigeration aids wine clarification in a number of ways.
Temperature reduction often halts yeast growth and the evolution of carbon dioxide, which keeps the yeast cells suspended. Also, carbon dioxide is more soluble at the lower temperatures that refrigeration can create.
Those in the know say a major cause of unwanted cloudiness is the slow precipitation of potassium acid tartrate as the wine ages. To avoid this, rapid precipitation is induced by lowering the temperature to about 19° to 23° for one or two weeks. If the wine that results is filtered off the tartrate deposit, tartrate precipitation will not normally cause later clouding.
The interest in variable-frequency drives that HVACR technicians are becoming more and more familiar with can also be seen in the wine making industry from some of the controls technology used in refrigeration, humidity and dehumidification. And it is also being used in irrigation. For example, the Seven Hills Vineyards in Oregon recently installed a state-of-the-art control system for its 1,265 acres. There are two main wells that will supply water to three large ponds, each of which will hold 10 million gallons. In each pond, there are pump stations to distribute water to the entire area for irrigation. The pumping system was engineered by Danfoss Drives’ water distributor Mitchell, Lewis and Staver.
In talking with those directly involved in the wine industry, there was one recurring theme. The technologies being used - refrigeration, humidification, dehumidification, variable-speed drives - are all familiar to skilled technicians in the HVACR industry. The wine industry is a growth sector of the economy and a potential growth market for the HVACR industry’s contractors and technicians.
For more information, visit www.winecellarinnovations.com, www.napatechnology.com, and www.envisioneering.danfoss.com.
Publication date: 08/27/2007