Sometimes the simplest methods are the best. Both because they are effective and easy to do. Cold crashing meets the “simple” criteria and is a great way to help you brew bright beer.
Cold crashing beer is a simple process used to clarify beer. Once your beer has reached its final gravity, place the fermentor in a cold and dark place like a keezer or a fridge. The colder the better but don’t freeze things. Wait for anywhere from 3 days to 2 weeks and proceed to kegging or bottling.
The main reason to cold crash is to end up with clearer beer in your glass. You’re essentially employing two things, time and temperature, to your advantage. This will help drop yeast and any other particulate matter down and out of your beer.
How Clear Will My Beer Be?
The goal is not to have perfectly clear beer when packaging. But transferring nearly clear beer is the goal. You’ll need to give it extra time in the keg or bottle to clear up to the point of being truly bright.
You don’t want to cold crash to the point of brilliantly clear beer unless your kegging. Remember that you need some yeast going into your bottles for carbonation purposes. Those are the yeast that will consume the priming sugar and you need some around to do that job.
How Effective is Cold Crashing
In short, very effective. But it depends (as always) on some factors. Yeast strain is a big one. Remember that you’re essentially speeding up the precipitation process when you chill your beer while cold crashing.
It makes sense then that certain yeast strains that are highly flocculant (drop out of solution quickly) will take less time to floc when cold crashing. And the opposite is also true. A low flocculating yeast will take more time.
One major drawback to cold crashing is the risk of oxidation. This is primarily a concern for anyone using a traditional air lock on their fermentor. As the beer inside the fermentor cools, the volume of beer decreases in size and something needs to take its place. Thus air is drawn into the fermentor through the airlock.
Oxygen is beer’s worst enemy post fermentation a.k.a. on the cold side. It makes it stale. If wet cardboard and sherry are your thing, by all means disregard this. But honestly, no one likes stale beer.
So, what should you do? You could choose to simply forego cold crashing altogether but you have other options…read on.
Best Ways to Cold Crash
As we just talked about in the “Why You Shouldn’t Cold Crash” section of this post, oxidation is enemy number one when cold crashing. So, it makes sense that some innovative homebrewers have come up with ways to avoid cold-side oxidation from cold crashing.
Number one on the list is to simply go out and purchase this nifty CO2 Harvester Kit from NorthCal Brewing Solutions. It’s about 50 bucks. That seems a bit steep to a tightwad like myself. But it will ensure that the only thing getting vacuum sucked into your fermentor while cold crashing is CO2. It’s a small price to pay for peace of mind and better beer.
The way this CO2 Harvester works is pretty simple. It captures CO2 being produced during active fermentation in a mason jar. That CO2 is then sucked back into the fermentor as things chill during cold crashing.
The Homemade CO2 Capture Method
Marshall Schott from Brulosophy came up with what he calls the The BrüLoonLock. It’s a mylar balloon modified and taped to a bung. You simply throw this balloon onto your fermentor right near the end of fermentation and voila! Your bag is filled with CO2 and you’re ready to cold crash.
This less elegant design has one major drawback. You have time when you put it on your fermentor perfectly. Otherwise you’ll end up blowing it off the fermentor. Not dangerous but potentially annoying.
Alternatively, if you keg, you could simply fill your balloon with CO2 from a tank. Then you’d just fit it to a bung and pop it on your fermentor before cold crashing. Cheap and easy.
Furthermore, if you wanted to transfer from a fermentor with a spigot towards the bottom you could do so without much oxygen exposure. But you will need to continuously top up the balloons with CO2 as you transfer, unless you have a giant balloon.
Ferment in Kegs
If you have kegs, you can ferment in them. Once fermentation is nearly done, simply close the pressure relief valve (assuming you fermented with it open). After the keg is sealed, you can cold crash without any environmental air making its way into the vessel.
Once you’re done cold crashing, simply do a closed transfer from the fermentation keg to a purged and sanitized serving keg.
The only drawback to this method is the reason so many brewers will never even try it…you get less beer. More is better right? Depends. Would you rather have 15 liters of excellent beer or 19 liters of just “ok” beer?
At any rate, the reason you’ll end up with less beer is this: Most kegs are 19 liters (about 5 gallons). By the time you leave headspace for fermentation and leave behind the trub post fermentation, you’re left with a measly 14 – 15 liters (about 4 gallons) of beer.
Even with the decrease in volume output I think that fermenting in kegs is a highly underutilized method for avoiding cold-side oxidation almost entirely. Not just oxidation from cold crashing but also from transferring your beer while packaging. If we can get over the “more is better” syndrome, then we may see more people utilizing kegs as fermentation vessels.
*All that ranting about keg size and it turns out you can get a 6 gallon keg from MoreBeer for about 100 bucks. That’s a better option for fermenting in but 7 gallons would be damn perfect!
Cold crashing is an effective way to help drop the gunk out and is a great way to improve your homebrew. But remember to take steps to avoid cold-side oxidation from the vacuum effect created while cold crashing. Enjoy bright beer!
Frequently Asked Questions
Some FAQs and answers!
How Do I Cold Crash Without a Fridge?
You’ll need a fridge, a keezer, or a glycol chilled fermentor in order to cold crash your beer. Also, cold weather.
What Temp Should I Cold Crash?
You want to cold crash at as 34 F if possible. This is as cold as you can reasonably get with a refrigerator without the risk of freezing. Freezing will kill your yeast but you can always add more when you bottle.
If you can’t get to 34 F, don’t worry. Anywhere in the 34 – 45 ish degree range will work. It just might take longer.
Should I Cold Crash A NEIPA / Hazy IPA?
Yes, you should. It won’t reduce any of the delicious hop compounds but it will help excess amounts of yeast drop out. Don’t worry, it will still be hazy.
Do I Need to Cold Crash My Beer?
No. You don’t need to. You can simply wait a couple weeks for things to settle out. But no one likes waiting. And so we came up with cold crashing.