Cold Crashing Beer for Crystal Clear Homebrew

Many brewers plan on brewing crisp and refreshing brews to tackle the summer heat. And while everyone has their favorite styles, most folks equate crisp and refreshing with light-colored and crystal clear pints of beer.

Clarity is not a priority for every brewer nor every brew, and many beers will turn out fairly clear without any help. But those lawnmower beers don’t look quite as refreshing if they’re hazy. Even without kegging systems or beer filtering equipment, there are some techniques that can help ensure clear beer. One of those techniques is called cold crashing.

Cold crashing is performed when the beer is fully fermented and ready to be packaged. The process involves lowering the temperature of the beer very quickly to near-freezing temperatures and holding it there for about 24 hours.

To cold crash, you’ll need two things:

1. Fermentation Temperature Controller
2. Refrigerator or temperature-controlled chest freezer/keezer big enough to hold a fermenter

The goal is to force the remaining beer yeast to flocculate (clump together and fall out of suspension) resulting in a crystal clear beer. This can be especially helpful when using a strain with low to medium flocculation performance.

When cold crashing a fermenter, the internal change of temperature may cause a drop in pressure inside the fermenter resulting in the air being pulled in through the airlock. This is not a reason to worry as there should still be more than enough CO2 blanketing the beer to prevent oxidation...as long as you do not shake it up too much moving it around.

If you keg your beer, you can cold-crash right in a keg. This allows you to purge the keg with CO2 and not even worry about oxygen getting in. Just seal the keg with an initial shot of Co2 then let the keg condition (uncarbonated) for a few days in your kegerator and the remaining yeast will drop out. Then just pour off 1-2 pints of yeasty beer from the bottom, and the rest of the keg should be crystal clear. If you want a very clear and stable beer, you can even push the beer to a second keg (using a keg jumper and CO2 pressure) leaving all the sediment behind.

If you are bottle conditioning, do not be concerned about too much yeast falling out of suspension. There are plenty of cells left in suspension and they should be able to carbonate your beer naturally in the bottle. Keep in mind, it may take longer than normal, depending on the yeast strain and the beer. Just give it time. If you need a quick turn around, you can always add dry yeast during the bottling process. Lallemand CBC-1 is designed for bottle conditioning. After cold crashing, bottle your beer and let the bottles carbonate at room temperature like normal. Read more about how to carbonate beer in bottles and kegs.

As a side effect, cold crashing will actually promote the occurrence of chill haze. While chill haze is best prevented earlier in the brewing process if it forms during the cold crashing stage, the use of gelatin finings will help clear that up before packaging.

Now let’s Brew, Share, and Enjoy some delicious summer beers!

Read More About Fermentation:

Fermentation - Learn about fermentation for beer.

Controlling Fermentation Temperature - Make sure your yeast is happy with the temperature. 

Stuck Fermentation - Helpful tips to get your fermentation rolling.  

How To Ferment For Higher Gravity -  If you’re making a high ABV beer, read this.

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