What Is Cold Crashing in Brewing（A）？

The bare-bones definition? It’s essentially using the cold to drop any suspended particles in your beer. Cold crashing is all about achieving crystal clear beer that looks just as appealing as commercially brewed beer.

Is cold crashing solely for making your beer crystal clear? Mostly, yes. However, there are other benefits to cold crashing that may surprise you.

There’s a reason why a lot of homebrewers adopt cold crashing in their brewing process. Some even regard it as a required step. But after reading this guide, you’ll be free to decide whether it’s for you or not.

What Is the Purpose of Cold Crashing?

The purpose of cold crashing is to accelerate the process of removing sediment or suspended particles in your beer. Cold crashing “forces” yeast particles to clump together and drop out of the solution.

The end result is crystal clear beer. Now, you might be wondering…are there any flavor benefits to cold crashing? So far, not so much. Nevertheless, it’s a simple process that requires 1 thing: a fridge.

Does Cold Crashing Clear Beer?

Yes, cold crashing helps clear your beer. During a cold crash, all the heavy particles in suspension fall to the bottom. These heavy particles left unfiltered could create a cloudy or hazy appearance in your beer.

Because cold crashing encourages these particles to fall out of suspension, you get a crisper, cleaner beer. Not to mention, the clarity of cold crashed beer has a striking appeal to it. And, it’s even known to be indistinguishable from commercial beers.

How Does Cold Crashing Work?

First, you need to understand flocculation. Flocculation is a term used to refer to yeast cells clumping together during the fermentation stage of beer. When yeast cells clump, they can either rise to the surface or fall to the bottom of your fermenter.

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Now, when does flocculation happen? It happens when the proteins in yeast (also known as flocculins) stick out their cell walls and attach to the cell walls of other yeast cells.

When brewers categorize yeast, they categorize it by how soon the yeast flocculates:

• High flocculation yeast: Yeast that clumps early (usually 3 to 5 days).

• Medium flocculation yeast: Yeast that clumps further during fermentation (6 to 15 days).

• Low flocculation yeast: Yeas that clumps late (usually after 15 days).

So, what does this have to do with cold crashing? For starters, using low flocculating yeast means you’ll see more yeast particles in suspension. Why? Because low flocculation yeast takes a while before it clumps together and drops to the bottom.

This is where cold crashing comes in.

Cold crashing encourages or forces yeast particles to clump together. When these yeast particles clump together, they sink to the bottom of your fermenter or fermentation vessel.

The keyword here is “encourages”. Without cold crashing, the yeast particles remain suspended in your beer. It’s one of the reasons why you might see a hazy or cloud appearance in your beer.

Sure – over time, yeast particles eventually sink to the bottom. However, the way cold crashing works is it accelerates the process of yeast particles sinking to the bottom. And the way it does this is by dropping the temperature of your beer to about 33°F (0.6°C) to 40°F (4.4°C).

Does Cold Crashing Affect Flavor?

Cold crashing doesn’t affect the flavor of your beer. An experiment conducted by a team did a study on the effects of cold crashing on beer’s flavor.

They brewed 2 types of beer. One that was cold crashed and one that wasn’t. The results revealed there was no difference in flavor between cold crashed beer and beer that wasn’t cold crashed.

If you want, you’re free to try it for yourself too.

When Should I Cold Crash My Beer?

You should cold crash your beer after fermentation is complete. This is important. You can only cold crash beer once your beer has fermented. Why is that so?

Remember how cold crashing works? It accelerates the process by encouraging yeast particles to sink to the bottom by dropping the temperature of beer.

The temperature ranges between 33°F (0.6°C) to 40°F (4.4°C). Once your beer hits this temperature, fermentation stops. And once fermentation stops, it means your yeast stops working too. If you cold crashed beer during fermentation, you prevent your beer from fermenting.

Confused? Here’s what you need to understand.

For yeast to work or do its job, it needs to be pitched at the right temperature. With the right pitching temperature, your yeast is active and awake. Without the right temperature, you either kill your yeast or, in the case of cold crashing, cause your yeast so sleep.

That’s the main reason why you should cold crash your beer after fermentation. And the best way to know fermentation is complete is through a hydrometer. After checking your beer’s final gravity, you’ll be able to tell whether fermentation is complete or not.