You've probably heard the term "cold crash" or simply "CC," but what does it actually mean? And why do we do it? In very brief terms, we use the term cold crash to describe cooling down the beer towards the end of the fermentation process. By rapidly lowering the temperature towards the end, proteins, yeast, and other particles in the finished beer will clump together and settle to the bottom. You can achieve a crystal-clear beer.
What temperature for cold crashing?
Cold crashing normally occurs at 0-4°C. The colder you can get it, the better (without freezing the beer, of course). When the beer has finished fermenting, it will naturally contain a percentage of alcohol. This alcohol will also prevent it from freezing, so feel free to go all the way down to zero degrees if you have the equipment for it.
A glycol chiller is specially designed for this purpose and can simultaneously temperature control several fermenters. A Ferminator fermentation chamber is also very popular, or a refrigerator if you have an empty one available.
How long should you cold crash?
How long you run this process is somewhat up to the brewer, but you will see results after a day or two. Beyond that, there's no problem if you want to cool even longer. Beer styles like pilsner and similar require significantly longer time, mainly because they need cold storage for maturation, but also because they should be perfectly clear.
Hazy beer styles will also benefit greatly from a cold crash, mainly to allow hop and yeast residues to settle. This should not affect the haze or result in a clear beer, but it will separate particles from the finished beer. Heavily dry-hopped beer types will especially benefit from this, and you will be able to get more beer out of the fermenter as the hops settle at the bottom of the vessel instead of at the bottom of the bottle or keg.
Benefits of cold crashing
- Particles and chill haze will settle, and you get a much clearer beer in a short time.
- Hops and yeast settle to the bottom, so there are fewer particles carried over when transferring to bottles or kegs. By separating hop trub from the rest of the beer, a cold crash can even ensure you get more beer from each batch.
- The beer is pre-chilled for fast and stable carbonation in a keg. Cold beer absorbs CO2 more easily than warm beer.
- Lagered beer needs a period of cold storage (lagering) to mature properly.
Precautions and tips for cold crashing
There are, of course, a few things to be aware of when it comes to cold crashing. When the temperature drops rapidly, a vacuum is created as the air in the fermenter contracts. This is often called "suckback," and it can cause damage to both the beer and, not least, the fermenter if precautions are not taken.
If you have a blow-off on your fermenter, meaning the airlock has been replaced with a hose in a bucket of water or Star San solution, this could be drawn back into the fermenter and mix with the beer.
If you seal the airlock on the fermenter so that it is completely airtight, you could, in the worst case, end up with the entire fermenter imploding. This can happen with both plastic and steel, and should be taken seriously.
If the airlock remains on as usual, air will be drawn into the fermenter when cold crashing begins.
In principle, you would be very unlucky if damage occurs due to air entering, but be aware that the risk is still present that you could draw in contaminated air (wild yeast, bacteria, and other unpleasant microorganisms that want a taste of your beer), or that a lot of air can contribute to increasing the risk of oxidation.
There are several methods to prevent suckback. Homemade solutions, such as filling a balloon or bag with CO2 and attaching it to an airlock or similar, are a simple and inexpensive alternative.
If you have a fermenter designed for pressure, this should not be a problem. You can simply apply a little overpressure to the fermenter before cold crashing begins. Alternatively, you can connect a special type of PRV / safety valve that compensates for vacuum. See our 1.5" Tri-Clamp vacuum PRV. This is also available in a 34mm Tri-Clamp version.
Ferminator
Ferminator Basic and Connect are our best-selling products for temperature control during fermentation, which also enable cold crashing. These are affordable fermentation chambers with integrated elements for both cooling and heating. Ferminator Connect can be controlled via Wi-Fi.
