MeinStein
Member
I'm new to brewing but have brewed about 6 batches since March. I read in a lot of posts about cold crashing. Could someone please explain what this is and when you would consider it?
Can someone please explain "Cold Crashing"?
- Thread starter MeinStein
- Start date
Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:
solbes
Well-Known Member
Cold crashing is putting your primary, carboy, or bottles into the fridge to force the yeast into dormancy. This causes most of them to drop out of solution, forming sediment on the vessel bottom. If you are doing this in a primary or secondary, you can rack the beer off the yeast, giving you clearer beer. Generally the colder the better, but obviously you don't want ice.
Works really well for some yeasts. I did this to a Kolsch last year and it cleared and conditioned really well. Mmmm Kolsch, can't wait to refill that pipeline.
Works really well for some yeasts. I did this to a Kolsch last year and it cleared and conditioned really well. Mmmm Kolsch, can't wait to refill that pipeline.
Cold crashing is when you chill your beer in order to force yeast and proteins to fall out of suspension. It's usually done before bottling or kegging- after fermentation and conditioning have been completed.
It's optional, it's not mandatory, some folks swear by it....
I opt for a month long primary myself. My beer is crystal clear. Plus I don't have an easy way to cold crash.
It's optional, it's not mandatory, some folks swear by it....
I opt for a month long primary myself. My beer is crystal clear. Plus I don't have an easy way to cold crash.
MeinStein
Member
Thanks for the quick reply, so this will help eliminate that yeast that seems to eventually appear in the bottle even if it looked clear giong in?
MeinStein
Member
Since it only goes into dormancy it has no effect on carbonation when you prime and bottle if bottle conditioning?
NO.
If youre bottle conditioning you beer, there will ALWAYS be some sediment in the bottom of the bottle. That's an inevitble part of bottle conditioned beers regardless of whether they're homebrew or commercial beers.
Whether you secondary or not, you're always going to have some.
This is my yeastcake for my Sri Lankin Stout that sat in primary for 5 weeks. Us-04 yeast IIRC.
Notice how tight the yeast cake is? None of that got racked over to my bottling bucket. And the beer is extremely clear.
That little bit of beer to the right is all of the 5 gallons that DIDN'T get vaccumed off the surface of the tight trub. Note how clear it is, there's little if any floaties in there.
When I put 5 gallons in my fermenter, I tend to get 5 gallons into bottles. The cake itself is like cement, it's about an inch thick and very, very dense, you can't just tilt your bucket and have it fall out. I had to use water pressure to get it to come out.
This is the last little bit of the same beer in the bottling bucket, this is the only sediment that made it though and that was done on purpose, when I rack I always make sure to rub the autosiphon across the bottom of the primary to make sure there's plenty of yeast in suspension to carb the beer, but my bottles are all crystal clear and have little sediment in them.
Half the time I forget to use moss, and you can't tell the difference in clarity.
I get the barest hint of sediment in my bottles....just enough for the yeast to have done the job of carbonating the beer.
The longer you chill your bottled beer, the further tighter your bottle sediment will be. I recommend a week. But the longer you leave it the less will come out. I have bottles in my fridge for months that when I pour them they are extremely clear, not a hint of sediment falls through, and there is no chill haze.
But even if you have sediment, who cares? You leave it behind when you pour anyway. It's called pouring to the shoulder.
Last edited by a moderator:
You *should* have enough viable yeast left over from a short cold crashing to carb your beer. It *may* take a little longer than not cold crashing. Remember, there are BILLIONS of yeast cells left over in your beer.
They should wake up and start eating the priming sugars after your cold crash.
You may want to think about bottling right from the cold container. Cold crashing can leave more dissolved CO2 in your fermenter, which will throw off your priming calculations, since you are starting with a beer that has more CO2 in it, and adding priming sugar. This will end up being more carbonated than a beer that is bottled at room temp. I think it will only be a problem if you cold crash and use more than the recommended amount of priming sugar too. But I've never taken a hard look at the calculations to know for sure.
I have never cold crash when bottling. I usually keg my beers now, so I have no risk of bottle bombs.
They should wake up and start eating the priming sugars after your cold crash.
You may want to think about bottling right from the cold container. Cold crashing can leave more dissolved CO2 in your fermenter, which will throw off your priming calculations, since you are starting with a beer that has more CO2 in it, and adding priming sugar. This will end up being more carbonated than a beer that is bottled at room temp. I think it will only be a problem if you cold crash and use more than the recommended amount of priming sugar too. But I've never taken a hard look at the calculations to know for sure.
I have never cold crash when bottling. I usually keg my beers now, so I have no risk of bottle bombs.
What Revvy said. However, cold crashing can greatly reduce the amount of sediment in your bottles. I've had beer that sat for 3-4 weeks before cold crashing and there is only a very small amount of sediment.
Also, your amount of sediment depends on how careful you are in racking into the bottling bucket.
Clearer beer can be helped by using a fining agent like irish moss, or gelatin or both. Then longer primary and/or secondary and cold crashing. And you have to consider the ingredients Some beers will be very hard to clear up without filtering.
There are many factors. Cold crashing is just one method to help.
Allow fermentation to complete before cold-crashing. This means a stable gravity for 2-3 days.
As long as you do this, just use the fermentation temperature when you calculate the residual CO2 to determine the amount of priming sugar and you will have no problems.
As long as you do this, just use the fermentation temperature when you calculate the residual CO2 to determine the amount of priming sugar and you will have no problems.
MeinStein
Member
Revvy
Thanks for the detailed reply. I have never had a yeast cake get that solid (in my limited experience) I dont mind the sediment, its natural, but you mentioned that when you put in 5 gallons of wort you generally get back 5 gallons. Does the extra time in the primary just allow the yeast to settle? Am I answering my own question?
Thanks for the detailed reply. I have never had a yeast cake get that solid (in my limited experience) I dont mind the sediment, its natural, but you mentioned that when you put in 5 gallons of wort you generally get back 5 gallons. Does the extra time in the primary just allow the yeast to settle? Am I answering my own question?
- Joined
- Mar 12, 2007
- Messages
- 6,841
- Reaction score
- 857
Not sure where this idea comes from, but it seem to persist here. The take I have I cold crashing is that it's a relatively quick drop in temperature to near freezing for the purpose of clearing the beer before transfer. Chilling bottles or kegs will help clear beer over time, but it's not what cold crashing is about. If it's not done before going into the final storage container it's simply refrigeration.
Yes. It allows the yeast cake to settle, and more importanly, it COMPRESSES and gets hard. So rather than your trub layer being very viscous and mixed with beer which you ultimately lose, the beer sits on top of a harder yeast layer, and when you rack you can pretty much rack like a vacuum the beer off the surface of the cake.
solbes
Well-Known Member
I don't think you can argue that the colder temps make the yeast cells go dormant. But I could be sold that it's not the dormancy that causes them to drop.
What is the actual phenomina that changes due to temperature that causes the beer to clear? Change in density? Something else?
I'm no chemist, but I'm given to understand that there is less activity in general at lower temperatures, all the way down. Your yeast would engage in less activity, which would produce less agitation of solids in solution. It should also have an influence on Brownian motion, which is molecules dancing their dance at the tiny level (that's technical talk)
I'm also interested to hear a reply about this.
My understanding is that cold temperatures absolutely cause yeast to go dormant, flocculate and sediment. And this helps clear the beer. And, as others have mentioned, cold temperatures also expedite sedimentation of additional suspended particles.
So, with this in mind, it really should not matter when the cold crash occurs. It should have the same effect. In primary, in secondary, in the keg or in the bottle.
But I'm open to other thoughts...
- Joined
- Mar 12, 2007
- Messages
- 6,841
- Reaction score
- 857
My point is that there's no "early" cold crashing. Any time you quickly drop the temperature before transferring to your final storage container, it's cold crashing. Chilling a bottle or keg that you'll be serving from is refrigeration, not cold crashing.
Curious to hear why you think that because you bottle you can't cold crash? If your worried about not having enough yeast left, don't. Cold crashing for a few days will not prevent your beer from carbing. You can transfer to bottles cold and then store them at room temperature for a few weeks.
I would especially cold crash if I bottled.
Here is how the "cold crashing" method actually works..
I am sure most of you know that when water gets hotter, it becomes more soluble, as in it will absorb more.. For example, 1 gallon of water at 70F will absorb roughly 38 grams of salt. If you raise the temperature to 140F, it will absorb considerably more salt. This is because the water "thins" at the higher temperature and has more "room" to absorb dissolved solids, such as salt. You have seen this before when you run your malt extracts under hot water to make them easier to pour out of the jars they come in.
Yeast in your beer follows the same principle. The types of yeast that we use are soluble in water (or beer) so when you cold crash your beer, you are doing the exact opposite of the heating process. By lowering the temperature of the beer, you are making it LESS soluble, and the yeast that is in suspension is forced to fall out and settle at the bottom.
I don't know brewing yet, but I am a chemist ;-)
I am sure most of you know that when water gets hotter, it becomes more soluble, as in it will absorb more.. For example, 1 gallon of water at 70F will absorb roughly 38 grams of salt. If you raise the temperature to 140F, it will absorb considerably more salt. This is because the water "thins" at the higher temperature and has more "room" to absorb dissolved solids, such as salt. You have seen this before when you run your malt extracts under hot water to make them easier to pour out of the jars they come in.
Yeast in your beer follows the same principle. The types of yeast that we use are soluble in water (or beer) so when you cold crash your beer, you are doing the exact opposite of the heating process. By lowering the temperature of the beer, you are making it LESS soluble, and the yeast that is in suspension is forced to fall out and settle at the bottom.
I don't know brewing yet, but I am a chemist ;-)
LVBen
Well-Known Member
Apparently, you are a very bad chemist. Yeast is NOT soluble! The ions and sugars do not drop out when we cool our beers, because sugars and brewing salts ARE soluble.
I think it's relatively common sense but common sense has failed me plenty of times in the past. Warm gases/liquids have a lot of molecular movement so yeast cells and other small solids will be bounced around in the liquid column. Of course, not all of it. Eventually all particles will fall to the bottom. However, getting the beer really cold slows the molecules down and let the sediment take a direct route to the bottom quicker.
One thing that people may not realize is that yeast cells don't swim when they are active. The reason why they are swirling around in the beer is from being carried around on the rising CO2 bubbles and the currents created by other rising CO2 bubbles. Once active fermentation is done, the one thing that can slow down the sedimentation are small increases in temperature which drive dissolved CO2 out of solution and pull all the crap back off the bottom. Therefore, cold crashing will also prevent this sort of thing. I suppose another way to ensure a faster clearing is to slightly degas with a vacuum.
One other sort of OT thing... kinda... I've noticed sedimentation happens quicker when the carboy is disturbed in any way. A little swirl or even transferring to a secondary. No, I don't mean leaving existing sediment behind. I mean after moving a cloudy beer to secondary, you'll see a rather immediate sediment layer. I suspect this is happening due to the degassing that happens or there may be some kind of surface tension issue at play that I just don't understand.
One thing that people may not realize is that yeast cells don't swim when they are active. The reason why they are swirling around in the beer is from being carried around on the rising CO2 bubbles and the currents created by other rising CO2 bubbles. Once active fermentation is done, the one thing that can slow down the sedimentation are small increases in temperature which drive dissolved CO2 out of solution and pull all the crap back off the bottom. Therefore, cold crashing will also prevent this sort of thing. I suppose another way to ensure a faster clearing is to slightly degas with a vacuum.
One other sort of OT thing... kinda... I've noticed sedimentation happens quicker when the carboy is disturbed in any way. A little swirl or even transferring to a secondary. No, I don't mean leaving existing sediment behind. I mean after moving a cloudy beer to secondary, you'll see a rather immediate sediment layer. I suspect this is happening due to the degassing that happens or there may be some kind of surface tension issue at play that I just don't understand.
Just to clarify... I do cold crash. I do this in primary. I never meant to infer I didn't. Its just that it's my understanding (and you seem to agree) that you can't cold crash before fermentation has completed (as you may want to do to emulate styles such as british bitters - there is a huge post about this on another thread) if you bottle. You can't do this with bottling because with bottling you let the temp rise back up after cold conditioning and added priming sugar to allow carbonation at room temperature. This would allow fermentation to restart and bottle bombs.
But the first part of what you said is what I don't understand. In my way of thinking, you CAN cold crash in the bottle. I don't do this but I would think you could. Although it may take longer for reasons suggested in later posts above.
Right, the benefit of cold crashing has nothing to do with setting FG.
- Joined
- Jun 2, 2008
- Messages
- 64,951
- Reaction score
- 16,516
There was a post on here from a "pro" brewer in Colorado who said that they do that (cold crash to set FG)....
Once they get where they wanted their FG; the cold crash, filter, and keg....
It didn't make sense to me, but he said he was the pro...
I suppose it works for when you can filter the yeast out but it wouldn't be practical on a homebrew scale. At least not using my logic.
This discussion is becoming highly technical. Shouldn't it be
moved to the Brew Science forum?
Ray
LVBen
Well-Known Member
Or the beer would have to be held at low temperatures until consumed. In the 32°-42°F range, most yeast activity should have ceased or at least decreased significantly.
- Joined
- Mar 12, 2007
- Messages
- 6,841
- Reaction score
- 857
We’re getting into nothing but semantics here, and I admit that this is only my take on the definition, but you can’t cold crash in a bottle. People have been refrigerating their beer for years and not calling it cold crashing. Does it clear the product over time? Sure. But cold crashing is a term developed to define a pre final packaging way of accomplishing this so that the beer is clear on the first draw from the tap or as soon as the bottle has carbed.
Cold crash and then package. Seems simple to me, but I could be wrong.
Anything that's soluble will fall out of solution if the temperature is lowered enough. Yeast is soluble. Different solids are soluble at different temperatures, which is why the yeast will fall out of suspension and sugars or whatever else don't. Another example of this is how starch isnt soluble until the water gets to 212F
If you were to pour 10oz of salt and 10oz of starch into a gallon of water, the salt would dissolve immediately, but the starch wouldn't dissolve until you bring it to a boil.
and apparently you are the bad chemist... ions aren't soluble. That's because ions aren't solids, they are charged particles, and they won't "dissolve" in water. In fact, this argument is irrelevant. Water (and beer) is covalent, not ionic. It seems that a lot of the brewing community is mixed up in this catagory.. the word you were looking for is "element"
Now that this has been brought up, I'm having a hard time understanding what being "soluble" means. Yeasts are organisms. Are organisms soluble? By your statement it appears that somehow, yes, this is possible. Where I'm having a problem is that it seems that there's a corollary, and that is that a swimming pool full of kids are water soluble because they're in the pool. What is the distinction that makes yeast soluble but children not?
What am I missing?
soluble is to be dissolved in a liquid to make a homogeneous solution (the smallest of particle size mixture) yeast is microscopic, that's why its soluble.. the basic idea is dissolved to where you cant tell where yeast is specifically.. with kids in a pool, you can pick them out (heterogeneous)
This actually clears it up (no pun intended) for me. I always thought cold crashing was defined as ramping the temperature down to clear beer. I did not realize it was a term specific to pre-packaging.
I agree with AnoldUR in that chilling beer is useful for different reasons throughout our processes but the specific term cold crashing is really specific to chilling cloudy post fermented beer in order to get it to drop clear faster than if you left it at ferment temps. I wouldn't get all excited if someone called in-bottle refrigeration "cold crashing" but I just don't think the term fits. If you don't cold crash in primary/secondary, you'd just wait an extra week to let it clear or package it cloudy.
StittsvilleJames
Well-Known Member
Well, if you are missing any children, I would try cold crashing your pool...
gr8shandini
Well-Known Member
Not quite. A solution happens at a molecular level. Yeast may be small, but they're way bigger than molecules. That's why you can filter the yeast out of your beer, but not any dissolved salts / gases.
Yeast floating in beer is a colloidal suspension, not a solution.
http://en.wikipedia.org/wiki/Colloid
Edit: Damn, dizzy beat me to the punch
Perhaps what happens in a cold crash is as the fluid is cooled the movement of the molecules slows as the liquid comes closer to what would be the freezing point. This reduction of kinetic energy might allow the larger particles of yeast being held in a colloidal suspension to fall out of "solution".
From the wikipedia article, it follows that the yeast falling out of the suspension is called flocculation in general, it matches the action in a collodial suspension. We have a winner! Dizzy and you.
LVBen
Well-Known Member
The information on that link is about molecules at gas, liquid, and solid states. The yeast cells are obviously in suspension, but I don't see anything that says that they are colloids. Do you have any link to something that says that organisms can be colloids or more specifically that yeast are colloids? Are humans colloids when we are swimming in the ocean or swimming pools? That Wikipedia link says that organisms can have colloids inside of them, but since organisms are made up of multiple molecules with liquid, solid, and gas inside of us, I don't see how that link is relevant.
The yeast will eventually drop out of suspension whether we crash cool or not. Cooling just makes it faster, because it decreases the amount of movement, making it more difficult for the cells to swim and drift upwards. If there is sugar left for the yeast, they'll stop eating it, and they will also no longer be creating the CO2 that helps them rise up into suspension.
To Crew, I didn't say that ions were soluble. I said that the salts we use in brewing are soluble. The temperature of the wort/beer certainly does affect the solubility of brewing salts and sugar.
