Refrigeration is one of the alcohol industry’s unsung heroes. Though rarely discussed, it plays such a vital role in breweries, cideries, distilleries, and wineries alike.
What’s the Need
When storing bottle wine for any extended period of time, it’s common knowledge that it must be kept under proper conditions. Typically this is somewhere around 13° C (55° F) and 70% humidity. It makes sense that temperature is important during wine production too, so much so that conservative estimates attribute over 30% of an average winery’s electrical expense to refrigeration.
Just like winemakers, winery refrigeration systems experience their greatest workload during the vintage period.
- Fruit arrives for processing at ambient temperatures, which can range up to 35° C (95° F). It’s common to want to get this juice cooled immediately to 2-10° C (35-50° F). Juice/must may be cooled prior to pressing, after pressing, or both depending on various factors: grape variety, cold settling vs. flotation vs. centrifuge, cold soaking or immediate ferment, etc.
- Fermenting juice/must is constantly producing heat during alcoholic fermentation. Fermentation temperatures for whites are typically 7-20° C (45-68° F), while reds will ferment between 20-27° C (68-80° F).
- In many wineries, the high level of activity increases the cellar’s ambient temperature. Anything from equipment running overtime to simply doors being opened and closed frequently can make a big difference.
With more temperature variation depending on the stage of maturation, temperature control is still very important outside of vintage. It will require plenty of refrigeration but may also require heating.
- Wines undergoing malolactic fermentation are typically held at 20-24° C (68-75° F).
- Barrel storage rooms require constant temperatures around 13-16° C (55-60° F).
- Clarification processes such as fining, centrifuging, filtering, and clarifying may need temperatures anywhere from 0-25° C (32-77 F).
- Sparkling wine, particularly those produced using the Charmat process, requires temperatures below 12° C (54° F) to promote carbonation.
- Bottling temperature is typically kept around 15° C (60° F), helping limit dissolved oxygen while allowing accurate fill heights.
Considerations for other Alcohol Producers
Differences in production requirements create variables that must be considered when choosing refrigeration equipment. Wineries and breweries would be on opposite ends of the spectrum with cideries and distilleries somewhere in between.
Breweries operate on a shorter, more regulated cycle than wineries. The time frame from brewing to bottle is typically a month or less, and the turnover creates a continuous demand for cooling. On the other hand, breweries operate in a broader temperature range than wineries due to the process flow:
- Boiled wort must be rapidly cooled after brewing from 100° C (230° F) to 7-20 °C (45-68° F) for fermentation.
- Conditioning and bright beer tanks will generally be maintained around 5° C (40° F).
- Bottling operations will often be completed close to 0° C (32° F).
Most people consider refrigeration the process of making things cold. Since heat is a form of energy and cannot be destroyed, refrigeration is really the transfer of heat from one place to another.
Commercial refrigeration units, air conditioners, and home refrigerators are all types of mechanical refrigeration systems, which can be simplified into 4 basic components: evaporator, condenser, compressor, and metering device (also known as expansion valve). A refrigerant is cycled through, transferring heat by changing states between liquid and gas:
- The compressor receives refrigerant gas at a low pressure and temperature, then discharges it to the condenser at a high temperature and pressure.
- The condenser converts this gas into a high pressure liquid, transferring heat from the refrigerant to the outside air.
- The metering device releases this liquid from the condenser at a decreased pressure into the evaporator.
- The evaporator uses the now cool refrigerant liquid to transfer more heat back into the cycle by converting it back to a gas state.
- The gas returns from the evaporator to the compressor, and the cycle continues anew.
A typical home refrigerator keeps food cold by using this cycle to transfer heat out of air, which is returned into the refrigerator cabinet to create a cooling effect. Winery refrigeration systems typically use a coolant liquid created using propylene glycol.