Cold crash. Purpose and Execution

[Louz]

I've picked up a few tid bits around here about cold crashing but I'm a bit confused.

From what I've read, a cold crash is solely for the purpose of "cleaning up" the brew. Resulting in all the sediment dropping to the bottom of the fermenter. Is that correct?
(I will be bottling my beers)

My current recipe (Dead Ringer IPA) instructions call for a secondary fermentation transfer after 1-2 weeks with a 1oz dry hop addition. Then 1-2 weeks before bottling.

At what point in the process should the cold crash be done? After active fermentation? How cold and for how long?

I want to end up with the cleanest beer I possibly can. I must admit, I hate having leftover yeast/sediment laying on the bottom of my beer. Are there any other steps available to avoid that?

 

[Jtk78]

Most around here will advise against transferring to a secondary vessel and I agree with them. Leave it be for about a week. Then check the gravity sample (drink the sample, DO NOT put it back in the carboy!) You should be at or very close to final gravity. If so, add your dry hops. 3-5 days later cold crash it.

Cold crashing is to get as much stuff that's still in suspension to settle out. Actually bumping the temperature up before this time can help the yeast in "cleaning up", but we're really referring to the yeast eating the last few meals before they go dormit, if you will. Be aware when cold crashing you can get "suck back". Do a little research on that to figure out how your going to deal with it. Many options are out there. My temp schedule may look like the following:
Pitch - 63F
First sign of fermentation (about 12hrs) - 63F
12-18 hrs later - 64F
24 hours later - 65F
48 hours later - 67F
48 hours later - 69F
10-14 days after pitch - 40F (I feel this prevents overshooting to low)
Once it's stable around 40F I'll turn it down to 32F

If you're bottling, you're probably going to have a little yeast on the bottom of the bottle. Leaving them in the fridge a few days will help it settle and pack down. Best to pour bottle conditioned beer in a glass leaving the last little bit. I've created some pretty clear bottle conditioned batches before.

 

[JimRausch]

Slight correction- cold crashing 'clears' beer, not 'cleans'. It helps sediment everything down into a nice compact layer that makes it easier to rack a clear beer at packaging time. If you choose to use a secondary, then a cold crash is not necessary, because racking from primary to secondary results in removing most of the sediment anyways. Although if you want to, cold crashing a secondary won't hurt.
Cold crashing is best done a couple days to a week before packaging. Get the beer down as close to 32*F as you can and leave it there for a couple days. Hitting it with gelatin after it's at chill temp helps as well.

 

[JimRausch]

Another thing- a slight pet peeve: Unless you are adding more fermentables, the second vessel is not a 'secondary fermenter'. It's more appropriate to call it a cold conditioning vessel, or maybe a brite tank. But everyone says secondary....... Maybe some day.

 

[SoCal-Doug]

Clearing 101:

If left alone long enough, most beers will clear. Some never will. "Long enough" might be days or months. It all depends on the ingredients. In theory, whenever your keg or bottles hit the fridge, they are being cold crashed, but its what you do during and after the crash to exclude the schmutz, that makes the difference.

"Cold crashing" Helps remove (settle out) a bit more stuff that is in suspension. Not a cure-all, but helps a little. If you cold crash AND use gelatin, the cold can also help "bring on" or "cause" some chill haze, then the gelatin will help remove more of it. Again, not always a perfect thing, but better than doing nothing.

If you are going to crash it, just wait until you know that fermentation is complete. Then go for the chill (preferably in the low 30's). No need to use a secondary, just stick the fermenter in the fridge. Add your gelatin and stir a bit. A few days later with gelatin, or a week or so later without, you'll see it settling out. Do your kegging or bottling now. If you plan to bottle condition it, you WILL have some dregs in the bottle. There's no way around that.

For the (as you say) clearest beer possible: Ferment to completion. Rack into keg. Add gelatin and shake the hell out of it. Chill overnight at about 34F. Put 30PSI of CO2 on it. Two days later, vent and bring the CO2 down to whatever serving pressure you require. A couple days later, pull off a couple nasty cloudy muddy pints (most the schmutz and gelatin will be at the bottom now). Then you should be good to go with fairly clear beer. In another week or two it will really clear (with more schmutz on the bottom). If you wish to bottle it now (carb'ed, clear and ready), use a counter pressure bottle filler to transfer from the keg to the bottles.

Option 2: Get yourself one of those half micron wonder pressure filter setups. I find them a pain to sterilize, prime, clean, pricey, wasteful, and not worth the money and effort over waiting a week or two with crashing and gelatin. Makes sense for larger scale pubs and breweries, not for 5 and 10 gallon home brewers.

Notes:

if you are using one of those low/non-flocculating yeasts or some wiz-bang juicy dry hopped turpentine bombs, it's probably not going to clear without mechanical filtering.

Use irish moss or whirlfloc. It does help a little and will make settling out of some of the compounds a bit faster.

no need to crash wheat beers or beers that are meant to be cloudy

gelatin: heat up a cup of water to 150F. mix and totally dissolve 1/4 tsp to 1/2 tsp of unflavored gelatin. dump it on in and stir a bit.

 

[ESBrewer]

I've picked up a few tid bits around here about cold crashing but I'm a bit confused.

From what I've read, a cold crash is solely for the purpose of "cleaning up" the brew. Resulting in all the sediment dropping to the bottom of the fermenter. Is that correct?
(I will be bottling my beers)

My current recipe (Dead Ringer IPA) instructions call for a secondary fermentation transfer after 1-2 weeks with a 1oz dry hop addition. Then 1-2 weeks before bottling.

At what point in the process should the cold crash be done? After active fermentation? How cold and for how long?

I want to end up with the cleanest beer I possibly can. I must admit, I hate having leftover yeast/sediment laying on the bottom of my beer. Are there any other steps available to avoid that?

There is a lot more you can do for clarity than one week in cold. Where should we start? There are different kinds of haze in the beer. Yeast is one thing and then there is another form of biological haze that is other (often unwanted) micro organisms. Then there can be unhydrolyzed starch particles from grains that remain floating around. And something that is called colloidal haze. This is generally so called chill haze that is formed by polyphenols (group of organic molecules) combined with proteins. The polyphenols come from grains and hops and the (mainly small molecular weight) proteins come from malts. The limiting factor in the formation of chill haze is the amount of polyphenols in the beer. It is called chill haze because it is not present when the beer is warm, but when you cool it down to serving temperatures, it may be overwhelming. So, chill haze is reversible and it always appears when things are cooled down because of the nature of the chemical (weak) interactions between proteins and polyphenols.

It is possible to combat the haze and sediments in each and every step of the brewing process. To get it as clear as possible (even at cold temperatures), a couple of key aspects are probably
- make sure mash/sparge pH and temperatures are optimal (especially pH <<6)
- vorlauf (or recirculate) the wort before you start collecting it from the mash tun (if using a traditional mash tun). This will form a grain filter through which the wort runs and prevents insoluble stuff entering the boil kettle
- ensure that there is enough calcium ions in the brewing water so that there is some calcium present when you start the boil (and even in the fermentation)
- use vigorous boil to form a good and complete "hot break"
- use more effective (rapid & extensive) cooling post boil to form a more complete "cold break" that essentially contains the chill haze forming molecules
- use carrageenan (Irish moss or preferably the more concentrated forms such as Whirlfloc/Protafloc) late in the boil
- now the break material (trub) contains a lot of the haze forming proteins and polyphenols, along with some other compounds -> to avoid chill haze, do not put this stuff to the fermenter
- rather than introducing trub to fermenter, let the trub settle down complete (when chilled), then use gentle flow rate when racking the clear phase and stop before the trub starts to enter the fermenter
- post fermentation, let the beer stand for a while so that yeast starts to settle down, use flocculent yeast strains, and use cold temperature to speed up the flocculation of yeast
- give it enough time in the cold (and use as cold as possible without freezing)
- the chill haze also starts to go down in cold, but it may take substantial amount of time (weeks for sure, yeast is often faster)
- to speed up the process, after a good cold crash, you can introduce some finings to the cold beer (gelatin from supermarket, isinglass(high-class version of gelatin), silica gel based beer finings, PVPP)
- I prefer fining with (silica +) gelatin because those are somewhat more natural products compared to PVPP which contains microscopic plastic particles
- if going with finings, be accustomed to the idea that they may take down some of the flavors and mouthfeel and thus, less is better (certain amount of protein and probably even polyphenols may sometimes be part of the character in your beer so it is a question of balance)
- some beer styles are meant to be hazy
- it is always better to drop things early in the process, because this will eventually make it more effective - especially the cooling efficiency is important for the chill haze and cold conditioning & time is important for all kinds of insoluble material hovering around
- when you bottle, do not introduce too much air (excessive head space) that will encourage the yeast to multiply more -> more yeast sediment
- understand that a new fermentation process takes place in the bottles so you need to give it time (and eventually some cold) so that the yeast drops down
- it is not possible to bottle carbonate without ANY sediment in the bottle, you just can't do it, I can't and top Belgian breweries cant do that - but the beer itself may be clear if you really want it

Of course there are additional things you can sometimes do, such as choosing malts and grains that contain less polyphenols / proteins or tend to release less starchy granules. Or pay more attention to the correct grain crush, maybe set up some commercial scale filtering devices... But carefully doing all the steps in the list above works great for me (using a very flocculent yeast).

If you (or google translator) can read German, this is a great take on beer clarity
https://braumagazin.de/article/bierfehler-des-quartals-biertruebung/

 

[eetu]

I think cold crashing has quite minimal impact on anything. If you have the equipment to do it without trouble, then why not. It does help the beer clear up a bit faster. But that's really that. I bottle my beers and after a week of refrigeration no one could tell if it was cold crashed or not prior to packaging.

 

[Louz]

Thank you all for your comments. A lot of great info. I will refer back to this thread often

 

[brandonlovesbeer]

Cold crashing brings out all of the hazy-beer proteins. This is the time to add gelatin. It will grab the chill haze proteins and drop them out of suspension.

I typically drop to around 33°F or as low as I can get it without freezing.
I usually hold it for a few days.