Stainless Steel Tanks
Known as inox vats in France, stainless steel tanks offer several advantages to the winemaker. They are easily maintained, sterilized and give the winemaker control over the fermentation temperature.
The use of Stainless Steel Tanks in Wine Production
Stainless steel tanks were first advocated by Emile Peynaud during the early 1960s. He observed their success in the dairy industry and thought that they could revolutionize winemaking as well. Chateau Haut Brion was listening to Peynaud. In 1961, this legendary Bordeaux producer was one of the first wineries in the world to install stainless steel tanks. Because of the benefits these fermentation containers offer, it was not long until many other wineries followed suit.
Along with alcohol and carbon dioxide, heat is a byproduct of the fermentation process. Fermentation will only take place between 38 and 90 degree Fahrenheit. The fermentation temperature has an enormous impact on the style of the finished wine. Red wines are typically fermented between 75 and 85 degrees whereas white wines prefer the 50 to 68 degrees range.
Warmer temperatures agitate the must and impart stronger flavors and aromas. While this is the goal for most red wines, it would produce a brash, unbalanced white wine. Cooler temperatures will retain the delicate varietal flavors and aromas that most white wines are valued for.
Stainless steel containers are very efficient at controlling the fermentation temperature. They have a chamber surrounding the tank that holds coolant and there are controls on the tank that allow the winemaker to maintain a certain temperature. Condensation appears on the tank when the liquid is cooled.
Stainless steel tanks also make it easier to prevent oxidation, monitor the fermentation and attach other winemaking tools. Most have closed tops in order to minimize the amount of air contact during the fermentation process. There is a small lid on the top of these tanks that allows the winemaker to monitor the fermentation and add ingredients to the must. The cap can also be punched down through this opening. Many have an attachment for a hose at the bottom of the tank to allow the winemaker to pump over the cap. This hose can also be used to rack the wine and transfer it to a different container.
Stainless steel tanks vary widely in size and can hold anywhere from 250 gallons to 200,000 gallons. They can be quite large, and are often over 20 feet tall. Stainless steel tanks used to ferment white wine are generally taller and skinnier than those used to ferment red wine. White wine tanks can be four times as tall as they are wide, whereas red wine tanks are rarely more than twice as tall as they are wide. The taller the tank is in relation to its width, the easier it is for the winemaker to control the temperature of the fermentation.
Stainless steel is completely neutral in the winemaking process. Unlike oak barrels, these containers do not impart any characteristics into the wine. This makes them useful not only for fermentation, but also as holding tanks. Wine is constantly being racked from tank to tank, and they are very useful during this process.
Stainless steel containers can also be used for cold stabilization. They are cooled to the point that suspended sediment in the wine begins to drop to the bottom of the container. The tartaric crystals and debris are then racked from the wine, giving it more clarity. Stainless steel tanks also have a longer useful life than other fermentation containers and can be more economical over the long term.
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