If you’ve been getting into homebrewing, you’ve likely seen the term ‘cold crash’ thrown around in forums or articles quite a bit. In this article, I’d like to go through how to cold crash and clear beer, and why you would want to do so!
What is Cold Crashing?
Cold crashing your beer is the act of decreasing the temperature of the beer after fermentation. This is performed to increase clarity of the finished beer. Cold crashing can be used as a method on its own, or in addition to using fining agents (discussed later on) to produce brilliant clarity.
Cold crashing can be as simple as placing your homebrew outside or in the garage in the winter months, or by using a refrigerator or temperature-controlled freezer.
Why Should I Cold Crash Beer?
I’m sure I’m not alone in the belief that some beers just tend to feel higher quality when they are brilliantly clear vs slightly hazy. Obviously, this completely depends on the beer style, hazy beers can be desirable in styles like the New England IPA. However, if you serve your friends a solid lager you just brewed, and it’s hazy, they may not be super impressed despite the aroma and flavor!
Cold crashing is a method to help produce this desirable brilliant clarity. It can be used to avoid using other fining agents or filtering, or it can be used along with those methods if you are short on time.
How to Cold Crash Beer
The first step to cold crashing your beer is to ensure that fermentation has completed. Whether you prefer to take serial final gravities or wait a set amount of time, please make sure that fermentation has completed. If you cold crash prior to the cessation of fermentation, you will either have an under-attenuated beer or the beer will complete fermentation during packaging (possible bottle bombs).
Once fermentation has completed, find space for your fermentor in a fridge, temperature-controlled freezer (I highly recommend the Inkbird Controller), or cold garage. Then you will simply let the beer sit and cool down! Please continue reading for further details on the process.
Best temperature to cold crash
The ideal cold crashing temperature is 35-40F. You do not want the liquid to freeze unless you’re making Apple Jack or an Eisbock!
How long to cold crash beer
I recommend cold crashing beer for at least 24 hours. However, some beers do take up to a couple weeks to clear sufficiently. This process can be sped up by using fining agents that are discussed in detail below.
Will cold crashing kill yeast?
No, fortunately, for your yeast friends, cold crashing will not kill yeast. It will, however, assist in helping the yeast go ‘dormant’. This is a state that you generally purchase your yeast in, and why the yeast requires refrigeration before being used.
Even though your beer will look much clearer, there will still be some yeast suspended in the beer after cold crashing.
Can I bottle condition after cold crashing?
Yes, you sure can. The above question about killing yeast is often asked in regards to bottle conditioning. As you need yeast present in the bottle to metabolize the priming sugar and produce CO2 as a byproduct, it is a very important question to ask.
Even though the yeast will go dormant when refrigerated, some yeast will still remain in suspension in your beer when bottled. When you add priming sugar, and let the bottles sit at room temperature for 2 weeks, the yeast will come out of dormancy to produce the CO2 you desire in your finished product!
It is important to let the bottles sit at room temperature and not leave them at 35-40F during bottle conditioning! As the yeast warms up, it will become active again.
How to Clear Beer Very Quickly
Often times, you do not have weeks or months to wait for a beer to clear on its own. I know I find myself in this position quite often. Let’s talk about ways to produce quality clear beer as quickly as we can.
- Kettle Finings
Kettle finings that are often used are Irish Moss and Whirlfloc tablets. Both of these products are made out of a certain type of seaweed and contain carrageenan. Carrageenan is negatively charged and works by attracting positively charged proteins and other molecules.
Kettle finings are added during the last 10-15 minutes of the boil. When the wort is cooled after the boil, these agents will help with the sedimentation of the molecules that it attracted.
I generally prefer to use Irish Moss in the smaller batches that I brew. A half tablet of Whirlfloc works very well in a 5 gallon batch, or a full tablet for a 10 gallon batch!
Fun fact, the scientific name for Irish Moss is Chondrus crispus, so if you’re looking for a crispy beer, look no further!
- Fermentor Fining Agents
These are fining agents that are added after fermentation has completed. The most commonly used products are gelatin, isinglass, and Biofine Clear.
Gelatin– A tried and true fining agent. Gelatin works best when the beer is cold crashed for at least 24 hours prior to adding. This product does require rehydration in water.
I like to add 1/4tsp of gelatin to 2oz of water for a one gallon batch (scale up accordingly for larger batches). Stir the mixture well, and then slowly heat the mixture to 160F in a microwave. I generally heat in 10 second bursts in the microwave, stirring in between. Once dissolved, add the mixture to your cold beer.
Gelatin is derived from bones, tendons, or hooves of horses or cows. Please keep this in mind if you are brewing for vegans. It can also strip tannins from beer/wine, so keep this is mind.
Isinglass– Another fining agent that has been used for decades, isinglass is derived from dried swim bladders of fish. Isinglass is positively charged, and therefore, strongly attracts negatively charged molecules. This works very well for clearing yeast products from your finished beer.
There are several different isinglass products for sale today, and they each require slightly different preparation methods. I would recommend following the instructions on the product you purchase closely.
As mentioned earlier with gelatin, if you are trying to avoid animal products completely in your beer, you would want to steer away from isinglass as well.
Biofine Clear– a relatively newer product to the market, Biofine Clear is a purified silicic acid solution. It works by clearing your beer of yeast and other haze-forming molecules.
I have found that Biofine Clear works well after cold crashing, similar to how I use gelatin. However, it does not explicitly say this on the provided instructions.
This is a product that can certainly be used in vegan-friendly beers, which fills a certain niche in the market.
Pectic enzyme– I feel that it is worth mentioning, if there is a potential that the haze in your beer is formed from fruit products, this may be ‘pectin haze’. Pectin is a molecule that hold fruits’ fiber together. When pectin is not sufficiently broken down during fermentation, a cloudiness can form. Pectic enzyme is a widely available product that can be used to successfully combat this pectin haze.
- Filtering– I’m not going to lie, this is a method that I have yet to personally use. However, when you want nothing but a brilliantly clear beer, filtering can be your ticket to success.
Filtering generally involves placing a filter canister between two corny kegs when transferring to your serving keg. This will quickly filter out all molecules larger than a certain size. If you would like to learn more about transferring from keg to keg, please see my article here.
This method obviously involves more expense and equipment, but it can produce a highly desirable appearing product extremely quickly.
- Cooling Wort Quickly– it is worth mentioning something called ‘chill haze’. Chill haze is formed when a beer is cooled lower than 35F. At this temperature, proteins and polyphenols form a bond that reflects light, and is thus, visible to the eye.
Two reasons that this often occurs in homebrew is too much oxygen exposure and/or an insufficient ‘cold break’ during chilling of the beer. To ensure that this cold break happens correctly, it is important to chill your wort after boiling very quickly.
Though we have been discussing ways to help to clear your beer quickly, I feel that this article would not be complete without mentioning a huge factor in beer clarity- TIME.
The vast majority of beers will clear on their own given enough time, especially when kept at cold temperatures.
If you are trying to avoid any further procedures or additions to your brewing protocol, that’s perfectly fine. After sufficient bottle conditioning, simply refrigerate your beer and it will eventually reach sufficient clarity.
Thank you so much for stopping by! If you have any questions, feel free to contact me!
If you enjoyed this article, please check out my other how-to articles!