If you’ve been brewing for any length of time you may have noticed that your beers, meads, ciders, and wines can come out looking cloudy or murky. If you have this problem, then you might consider cold crashing your beer to help clarify your brew.
What Is Cold Crashing?
Cold crashing is when you take beer that has completed fermentation and put it in cold storage, close to freezing. This is generally a refrigerator or modified chest freezer designed to control fermentation temperatures.
When beer is cold crashed, the yeast and proteins suspended in the beer sink to the bottom and form what’s known as “lees” or “trub”.
Why Would I Want Trub?
It’s not the trub you’re after. It’s the clarity in the beer or wine that comes from cold crashing that you want. When beer is rapidly cooled to a near-freezing temperature, the yeast and protein floating in it tend to flocculate (a fancy word meaning “group together”) making them heavy so that they fall to the bottom of the fermenter.
This means less yeast and protein floating in your beer. Floating or suspended yeast and protein is usually the cause of beer, wine, or cider that has a hazy appearance. By cold crashing, your beer will pour clear until the bottom of the keg.
If you’ve ever wanted to brew beer that has the same clarity as the popular commercial beers, the best way to get there is by cold crashing.
What Are The Downsides?
Cold crashing is not without its downsides. There are several things the cold crashing home brewer needs to be aware of and account for.
First, to successfully cold crash, you need fairly precise temperature control. If you already have a modified chest freezer or a refrigerator used to control fermentation temperatures, then you’re set. If you have a kegerator or keezer, those are often already configured for the right temperatures.
Obviously, kegging your beer gives you an advantage here. It’s going to be harder to be successful with fermentation control when you use simpler methods like ice packs and insulating materials, and if you bottle beer before refrigerating it, it’s going to be even more difficult.
The second downside is that cold crashing can in some situations prolong the time it takes to make your beer. Cold crashing takes several days to work properly, which is several days of not drinking your delicious homebrew.
Finally, special consideration needs to be taken to account for what is known as “suck back”. As the beer and air in the fermentation chamber cool down, CO2 begins to dissolve into the brewing beer. This causes the air in the chamber to become more dense, which in turn causes the pressure to drop and air from outside the vessel to be sucked inside.
You’ll want to be sure to avoid this, as failing to do so can cause the beer to become oxidized or even infected by airborne bacteria or wild yeast.
How to Cold Crash Your Beer?
As noted above, the first and most obvious thing you’ll need is some sort of temperature-controlled storage. This is most commonly either a refrigerator or a modified chest freezer.
Whatever your solution is, you’ll want to place your fermentation vessel into this for a period of 48 to 72 hours at a temperature range of 32 to 38 degrees Fahrenheit. Higher ABV beers are safer to put at the bottom end of this range.
If you can’t reach temperatures as low as these, it’s still worth it to cold crash – it’ll just take longer to get results. A beer cold crashed at 32 degrees might be good to go in two days, while a beer crashed at 50 degrees might take a week or more to clear up. But both will clarify.
It’s not necessary to transfer your beer from its primary fermentation vessel into a secondary one to cold crash, but if you’re kegging the beer it’s a good idea to transfer it into the keg before cold crashing.
In addition to temperature control, you’ll need a way to manage suck back. If you’re cold crashing with a keg, you can manage it by purging the keg with CO2 and pressurizing the keg. This way any air absorbed by the beer will be pure clean CO2 and you can carbonate your beer and cold crash at the same time.
If you’re bottling your beer, there are two common workarounds to this problem. The first is to strap a balloon to the top of the fermenter just before it’s finished fermenting and still producing some CO2. If you time it right, you’ll fill the balloon with CO2 without popping it or making it fly away.
This fermenter and balloon can then be moved into your cold crashing chamber and when the beer tries to suck air back in, it will instead draw the CO2 from the balloon. This may take some practice, but many home brewers successfully use this technique.
Another common workaround is to simply bottle your beer and, once carbonated, leave the bottles in the refrigerator for several days before drinking. While you may end up with yeast and trub in the bottom of your bottles, most if not all of this can be left there with a careful and deliberate pour.
Are There Any Alternatives?
If you’re unable to cold crash there are indeed several other options that will help clear up your brew.
The first is also the cheapest: time. Simply wait and your beer will eventually clear itself up. The downside is that it can take weeks or months before you end up with a truly clear beer, but if this is your only option it’ll get the job done.
The second option is gelatin. That’s right, the same stuff you use to make Jello. Measure out ½ a teaspoon of unflavored gelatin per five gallons batch of your beer, then dissolve and boil it in water for a few minutes. Add this to your fermentation vessel and it’ll help clear up your beer.
This works because the gelatin molecules attach themselves to the yeast and protein, making them heavier so they drop faster. Gelatin is extremely popular as a clarifying agent and is often used at the same time as cold crashing to give an even clearer beer even more quickly.
Products like Isinglass or Super Kleer work much like gelatin but may give even better results. These products are more often used for wine or mead since they’re more expensive than gelatin.
As you can see, there are many alternatives to cold crashing as well as options that can be used in conjunction with it to give you the clarity you’re looking for. It’s worth it to give all of them a try at least once to see what works best for you.
