Cold crashing beer is a technique implemented by many brewers to produce crystal clear beer and improve the level of clarity by removing unsightly sediment and yeast.
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What is Cold Crashing Beer?
It is the last step in the brewing process right before you bottle or keg your beer. It improves the clarity of the beer by lowering its temperature to just above freezing. The colder temperatures cause the solids such as the remaining yeast, hop debris, and proteins that are still in suspension within the beer to clump together and drop to the bottom of the fermenter.
Should You Cold Crash Your Beer?
Deciding whether to cold crash your beer or not is a personal preference. The proteins within the beer that cause the beer to have a cloudy appearance are perfectly safe to drink and do not affect the flavor of the beer. The sole purpose of cold crashing is to produce a clear beer, if you don’t mind having a slight cloudiness to your beer then you do not need to cold crash.
However, If you are entering your beer into a competition it is strongly recommended to cold crash it as most beers (although not all) are judged on their clarity. Keep in mind that some beers such as a NEIPA are meant to have a cloudy and hazy look and as such, you would skip this process with those styles.
When to Cold Crash Beer
The best time to cold-crash beer is 2 – 4 days before it is ready to be bottled or kegged. The first step is to determine that the final gravity has been reached. In order to determine the final gravity, it is important to learn how to read a hydrometer.
When the gravity has stopped moving for 2 days you can be assured that fermentation has finished, it is then recommended that you leave the beer sit in the fermenter for a few more days in order to allow it to condition properly and give the yeast time to clean itself up.
How Long to Cold Crash
At the very least you should cold crash for 24 hours. This is the bare minimum time it will take for all of the debris to drop out of suspension. Industry-wide it is generally agreed that the ideal time frame to produce very clear beer is 48 hours.
Do not be concerned if you go longer than 48 hours it is not going to hurt your beer, in fact, lagering beer is really just an extended cold crash. The worst that could happen is the yeast that is left in suspension will be dormant and if you are bottling your beer it might take the yeast longer to wake up resulting in it taking slightly longer to carbonate your beer in the bottle.
If this is a concern let your bottles sit in a room temperature space in your home for 2 -3 weeks which will be a sufficient amount of time for the yeast to wake up and for carbonation to occur.
How to Cold Crash Beer
Simply take the primary fermenter the beer fermented in and 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.
Some brewers will rack (transfer) their homebrew from the primary fermenter to a secondary and then cold crash. The rationale for this technique is they believe that leaving behind all of the trub that has formed at the bottom of the primary fermenter will result in a clearer beer.
We do not recommend this technique due to concerns of oxidation; which is air getting into your beer and contaminating it and causing off flavors; we advise exposing your beer to as little oxygen as possible in the brewing process.
How to Cold Crash Without a Fridge
There are a few options available to people who do not have a spare refrigerator available for cold crashing.
The first option is to use a freezer and modify it into a Keezer of sorts. In order to do so, you will need to pick up a temperature-controlling device such as an Ink Bird to control the temperature and keep it at fridge temperatures.
Another option is 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 as it melts.
And lastly, if you live in a cold climate depending on the time of the year you can consider cold crashing your beer outside or in your garage as long as temperatures stay above freezing. Be careful not to allow your beer to freeze or you may mistakenly end up making ice beer.
How to Avoid Oxidization
There is not a huge risk of oxidization when cold crashing your beer but it is 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 which if you are not prepared for it in advance can result in oxygen and the liquid from the airlock being sucked into the fermenter and into your beer.
Oxygen 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 get sucked into the beer either.
Simple solutions are to remove the airlock and put a bung in its place. If you don’t have a bung use tin foil or saran wrap and put it over the mouth of the fermenter where the airlock was, securing it in place with an elastic. 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.
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Other Methods of Clearing Beer
If your goal is to create a crystal clear beer there are other techniques you can implement alongside cold crashing.
Whirlfloc or Irish moss is kettle finings that can be added towards the end of your boil to help clear your beer. Add them with 15 – 20 minutes left in your boil.
Whirlpooling at the end of your boil before you chill is another tactic some brewers use. Simply stir the wort for a couple of minutes and create a whirlpool effect within the kettle, this will separate the wort from the trub and hop debris. Let the wort rest for 10 – 20 minutes after whirlpooling before moving on to cooling your wort.
You can also add fining agents such as gelatin directly to your kegs to help clear the beer. Adding gelatin is a technique known to create very clear beer.
Another option is to use an inline filter to help remove debris particles. The bouncer beer filter is one such option.
And lastly, time is an excellent way to produce clear beer. Allowing your beer to condition by letting it sit in the bottle or keg for a few weeks will give the trub and hop debris ample time to fall to the bottom.
This post goes into further details on how to clear home brew beer.
If you prefer your beer to resemble crystal clear commercial beer styles, then cold crashing beer is a simple technique you should implement that only adds an extra 2 days to the brewing process but produces excellent results.
P.S. Be sure to check out our gift to you, on the side of the blog or at the bottom on your smart device you can get access to Robb’s top 5 best-selling recipes from his brewpub. Cheers!