Where is cooling used when making wine?
The art of winemaking goes back centuries. Over the years, technology has improved enabling greater experimentation and refinement in the winemaking process. However, a well-maintained temperature system remains at the core of producing a great tasting final product. Whether looking to break into the wine industry or seeking to update existing wine systems, understanding the role of refrigeration in the process helps users to better manage their set-ups.
Temperature control impacts several distinct steps in the winemaking process:
Must Cooling
Must is the freshly crushed grapes. This mixture contains skins, seeds, and stems of the fruit. Creating the must is the first step in the winemaking process. In the commonly evoked images of medieval people stomping in large barrels the juicy grape mush is the must. Though only the beginning, the length and temperature at which the must stays in this stage influences the final flavors of the wine. The must should be kept around 40° F in order to limit phenolic oxidation and premature fermentation. Sometimes vintners will employ cryomaceration, which involves a deep cooling almost to a freezing of the must. Cryomaceration extracts greater flavor compounds from the grape skins than other must cooling options.
Juice Clarification
After further processing of the must, only the juice remains. Once again cooling becomes a crucial element. A good quality wine should be “clear” with no visible particles in the liquid. In order to avoid the dull & cloudy look, the pre-fermented juice must undergo clarification. Depending on the variety of grape and the specifics of the wine, different methods can be used. However, the most common method across varieties involves using a cooling jacket around the wine barrels. The exact temperature will vary depending on the type of wine, but should be somewhere between 50-58° F. At the lower temperature, much of the acidic components, which contribute to cloudiness, break down.
Fermentation
This step is generally the longest in the process. It involves the careful management of added yeast, which break down the sugars present in the juice. As the yeast consume the sugar, the liquid ferments and receives its alcoholic content. Of course, this process is very particular, as yeast are feisty fellows. Many factors contribute to the rate of fermentation and the final flavor, but temperature remains the key determinant. Temperature must be properly set and maintained in order to produce flavorful wine. Fermentation is an exothermic reaction, meaning it releases heat. The cooling system must be able to remove this naturally created heat before the mixture becomes too hot. The fermentation process could stop if temperatures become too high.
Generally, industrial chillers will cool the fermentation tanks. The chiller moves cooling fluid through the tank to absorb and remove the heat. The result is a lowered temperature in the tank. Chillers can also typically provide valuable process information such as temperature readings. Depending on the model of the chiller, users may even be able to adjust temperature settings to correspond with the needs of the particular wine.
Certain fermentation processes even require the addition of heat in order to produce the desire final product. The heat prevents malolactic fermentation and protects the wine from developing a bad taste. Chase Cooling Systems offers a heating pump option on our CWE/HWE series. With the proper set-up, one unit can be used to either heat or cool the process.
Cold Stabilization
Once the juice has fermented, it has to undergo cold stabilization. A common biproduct of the fermentation process is potassium bitartrate, which can crystalize and form precipitate in the wine. This sediment can create an unpleasant appearance, and it is best if it is removed prior to bottling. By rapidly lowering the temperature of the fermented juice, much of the tartaric acid will precipitate out. The liquid can then be filtered and bottled. The bottled liquid should form significantly less sediment after the cold stabilization process.
Wine Storage
Once the wine is bottled, it must be kept at the proper temperature for storage. Temperature is particularly important if the wine will not be served immediately. Finding the “perfect” temperature depends on the specifics of the wine but generally is in the 62-68° F for reds and 49-55° F range for whites. Maintaining these temperatures helps to limit the rate of oxidation and the volatility of the aroma compounds. Essentially, the cooler temperatures protect and preserves the wine, making it enjoyable for a longer time and better ready for market. In ambient temperatures above 70° F a wine can begin to age and lose its flavors.
Space Cooling
Outside of the actual winemaking process lays another need for refrigeration. The general space where the process occurs and where wine barrels are kept should be temperature controlled. As demonstrated above, the winemaking process is very particular and the smallest changes in temperature can have large effects on the final product. Hence, why caves often served as wine cellars in the early days. The most common method to achieve this periphery cooling is by utilizing some type of HVAC system.
In summary…
Refrigeration plays a role in almost every step of the winemaking process. Though different refrigeration methods may be utilized throughout, the impacts are very real. Understanding how temperature effects this delicate process is crucial to producing successful final product.
To discuss the specific needs of your winemaking system, be sure to call a cooling engineer at Chase Cooling Systems. Or send an email to sales@chasechillers.com. We would love to help work you through that final hurdle to producing consistent delicious product.