I can remember back when I first started homebrewing; way before I had ever heard of brewing techniques like cold crashing beer; Man was I excited about making my first batch of homebrew.
Oh man I couldn’t wait to try that first pour.
I can recall like it was yesterday carefully taking the beer bottle out of the fridge, twisting the cap, relishing in the incredible hissing sound it made, titling my beer mug ever so slightly as I got ready to pour this delicious and what I imagined crystal clear liquid into my mug only to be rudely interrupted from my fantasy by a cloudy and hazy looking concoction that was filled with little floaty things floating all around in it.
My visions of brewing a commercial clear beer in my kitchen came crashing down hard.
However, after much research, trial and error as well as experience eventually I figured out how to brew very clear and crisp looking beer. I now accomplish this using a few different techniques to include cold crashing which we are going to take a look at in detail today.
What is Cold Crashing Beer?
The very basics of cold crashing are that after your beer has finished fermenting you place the fermenter into a cold area. Most people will use a fridge or a freezer that has an adapter attached to it to regulate the temperature and keep it at fridge temperatures.
Don’t worry about an exact temperature; remember this is make beer easy after all, however strive to get the temperature down close to 2- 4 degrees C or 35 – 40 degrees F.
You leave your beer to cold crash at these temperatures for 24 – 72 hours, or longer if you like.
A more detailed explanation is that the cold temperature makes the gunk that is floating around in the fermenter come together and clump up. You will see the clumps of gunk form (debris from hops, yeast, other proteins and solids). And you will see them fall out of suspension to the bottom of your fermenter.
The technical term for the yeast clumping together and falling out of suspension is called flocculation.
All of this gunk that settles on the bottom of the fermenter forms the trub.
With all of this gunk no longer in suspension within the beer it becomes much cleaner and crisper looking. If you left this debris in suspension your beers would have a much hazier and cloudier appearance. And in fact with some beer you want that to happen.
New England IPA’s (NEIPA) for example you would not cold crash, as you are striving for that hazy cloudy look. Same goes for many wheat beers.
Myself I prefer a clear, clean and crisp looking beer so I cold crash pretty much every batch of homebrew.
Cold Crashing Instructional Video
When to Start Cold Crashing
The best time to cold crash your homebrew is 2 – 4 days before you are ready to bottle or keg your brew. Wait until your final gravity has been reached. If you don’t know how to check to see when your final gravity has been reached you can check out this post; How to read a hydrometer.
This also allows you plenty of time to dry hop your beer if you are doing so. You want to dry hop before cold crashing, typically about 7 – 10 days into fermentation. But again if you are brewing an NEIPA you want the hop debris to remain suspended in the liquid so you will not cold crash.
How to Cold Crash Homebrew
You can either simply take the primary fermenter the beer fermented in and literally move it to a fridge or a freezer that is temperature controlled to maintain fridge temperatures and let it sit there for 2 – 4 days.
Or some people rack (transfer) their homebrew from the primary fermenter to secondary and then cold crash. Their rationale is that they are leaving behind all of the trub that has already formed at the bottom of the primary fermenter.
I do not do this out of concerns of oxidation; which is air getting into your homebrew and contaminating it, I prefer to expose my brew to as little oxygen as possible in the brewing process.
Watch Out For Air Vacuum
This is not a major concern but something to be aware of. As the temperature drops within the fermenter a vacuum occurs. This is caused by the air in the fermenter contracting resulting in air and liquid from the airlock being sucked into the fermenter and into your homebrew.
As we have discussed, air is not a good thing to have get in your beer during most of the brewing process and it is never a great thing to have sanitizer from the airlock get sucked into the beer either.
Simple solutions are to remove the airlock and put a bung in its place. I also have taken tin foil or saran wrap and put it over the mouth of the fermenter where the air lock was, I use an elastic to seal it into place. Some people will also put vodka in the airlock so that if any liquid gets in it is the vodka and not water or sanitizer. All of these solutions work great.
How to Cold Crash Without a Fridge
So what can you do if you do not have space in your fridge for a fermenter or you do not have a spare fridge you can use for brewing.
Well I have briefly touched on one solution which is to use a freezer. If you use a freezer you will need to pick up a temperature controlling device such as an Ink Bird to control the temperature within the freezer and keep it above freezing and at fridge temperatures.
Lots of people who do this also use the freezer as a keezer. They store their kegs of beer in them for serving as well so it has a dual-purpose.
Outside of a freezer you can get creative with other methods.
I live in Canada so depending on the time of the year I have actually been able to cold crash outside when temps were just above freezing. I have also been able to cold crash in my garage in the winter as temperatures typically stay above freezing. But you have to be careful as frozen home brew is not a good thing.
Another option you could try would be to cold crash in a swamp box cooler. Put your fermenter in a big container filled with ice water and ice packs. Drap a wet towel around the fermenter and make sure the edges of the towel are soaking in the water. Replace the ice packs and add more ice every 12 hours.
So Should You Cold Crash Your Beer?
That my friend is 100% a call you will have to make. There are times I don’t cold crash my beer and there are times I do.
Again it depends on the type of homebrew I am making and it also depends on how much of a rush I am in to get some beer brewed up as well as how much space I have available in my fridge and keezer.
In the end it is really just a matter of preference when it comes to how you want your beer to look. Taste wise there is very little if any difference.
There are other things you can do along with and instead of cold crashing to make your beer clearer.
What Else Can You Do to Clear Your Beer?
Whirlfloc or Irish moss are kettle finings that can be added towards the end of your boil to help clear your beer. I use whirlfloc in pretty much every batch of beer I brew except NEIPA’s.
Whirlpooling at the end of your boil before you chill is also another tactic some brewers use. Simply stir the wort for a couple of minutes and create a whirlpool within the kettle, this will separate the wort from the trub and hop debris.
Let the wort rest for 10 – 20 minutes after you whirlpool it before moving into the chilling process.
You can also add fining agents such as gelatin directly to your kegs to help clear the beer. Gelatin does a really good job of clearing your beer.
And lastly time is an excellent way to clear your beer. Let your beer sit in the bottle or kegs for a few weeks and the trub and hop debris will fall to the bottom on its own.
This post will give you more details and ideas on how to clear home brew beer.
There you have it my friend you now know exactly how to cold crash your beer. Give it a try and let me know how you make out.
If you have any questions drop them in the comments and I will be sure to help you out.
Cheers & Get Y’er Brew Awwwnn!
P.S. If you want to make sure you are brewing the best tasting beer possible be sure to sign up for my Free Brewing Tips on the side of the blog, and get yourself a Free copy of my favorite Beer Recipes while you’re at it.