Rethinking the logic of cold crashing

[aidan]

I've read lots of topics on here about cold crashing and have asked my own questions about it too. For my first 3 batches of beer I did cold crashing for 5 days after 2 weeks of fermentation. The beer did turn out good but I'm beginning to wonder if cold crashing after 2 weeks fermentation is a good idea at all. I don't do secondary, just primary and I usually give it 2 weeks to ferment.

One thing I read on this forum (sorry I can't find the thread now) got me thinking that perhaps cold crashing might interfere with the conditioning process. It was something about temperature fluctuations being bad for the yeast. So I was thinking that after 2 weeks the beer is in the conditioning phase and if you bottle it then it will continue conditioning in the bottles. But if you cold crash it at that point, won't you will interfere with the yeast's conditioning work and pre-maturely end the conditioning phase? I can see that if you rack to a secondary and then leave it a few more weeks for conditioning, then cold crashing would be fine since the yeast will already have done most of their conditioning work. So now I'm thinking that for the type of brewing that I do, i.e. 2 week primary and no secondary, that cold crashing may do more harm than good. What do you think?

 

[MalFet]

Even after crash cooling, there is still a significant population of yeast in suspension. You don't need much yeast to process intermediate metabolic compounds ("clean up"), and the cold crashing can actually help suspended solids drop out into the trub. That said, yeast metabolism is pretty darn slow at 40F, so you won't have much activity during that time.

I don't crash cool, just because I have never needed to. But, that said, I don't suspect it actually causes any harm.

 

[weirdboy]

I cold crash just before packaging. If you want to condition then do so and cold crash later.

 

[aidan]

Even after crash cooling, there is still a significant population of yeast in suspension. You don't need much yeast to process intermediate metabolic compounds ("clean up"), and the cold crashing can actually help suspended solids drop out into the trub. That said, yeast metabolism is pretty darn slow at 40F, so you won't have much activity during that time.

I don't crash cool, just because I have never needed to. But, that said, I don't suspect it actually causes any harm.

Yes I realise there is still a significant yeast population but it would be significantly reduced after the cold crash. I've read that logic behind why conditioning in the primary is supposed to be better than conditioning in a secondary is because there is much more yeast at work when it's sitting on the cake. Extending that logic to the bottle conditioning - you would have significantly more yeast at work on bottle conditioning if you didn't cold crash vs. if you did. So following that logic you would get better bottle conditioning action by skipping the cold crash. But I dunno, just my thoughts on it.

 

[theredben]

Bottle conditioning reactions are not going to be 1:1 related to yeast population, many of those compounds take time to disappear. More yeast does not help, nor does less yeast hinder it.

 

[MalFet]

Yes I realise there is still a significant yeast population but it would be significantly reduced after the cold crash. I've read that logic behind why conditioning in the primary is supposed to be better than conditioning in a secondary is because there is much more yeast at work when it's sitting on the cake. Extending that logic to the bottle conditioning - you would have significantly more yeast at work on bottle conditioning if you didn't cold crash vs. if you did. So following that logic you would get better bottle conditioning action by skipping the cold crash. But I dunno, just my thoughts on it.

Based on my understanding of it, the analogy to secondary doesn't work.

First, I've not seen much evidence to suggest that the yeast cake is actually beneficial during conditioning. I don't think it is harmful, and skipping secondary lets you avoid a transfer that very much can be harmful. That said, if you have any links pointing to the role of the yeast cake in conditioning I would love to read them.

Also, as theredben mentioned, the conditioning reactions are not depended on yeast population, just on yeast presence. Many of them are purely mechanical and don't even require yeast at all.

Standard practice for bottle conditioning is to get about 100,000 cells/mL. I believe Kaiser had a project somewhere doing a side-by-side test and determined that more can actually be worse, but I can't find the link right now. His experiment was small and on maibocks, but I think he found that too much yeast actually prevented aging reactions related to oxygen that are desirable for some styles.

In any case, give it a side-by-side blind taste test and see what you come up with. I'm sure everyone would love to see some data on this

 

[aidan]

Based on my understanding of it, the analogy to secondary doesn't work.

First, I've not seen much evidence to suggest that the yeast cake is actually beneficial during conditioning. I don't think it is harmful, and skipping secondary lets you avoid a transfer that very much can be harmful. That said, if you have any links pointing to the role of the yeast cake in conditioning I would love to read them.

Don't have any specific links to point to, it was just stuff I read on this forum, i.e people's opinions, theorising, etc.

In any case one of the questions I'd like to hear some opinions on is, if I've fermented for 2 weeks in primary and I'm going to give it another 4 or 5 days in primary before bottling, am I better using that time for cold crashing or just leave it at fermentation temperature to continue conditioning process?

 

[UrbanBrew]

I was under the impression that you cold crash after secondary. That said if you don't secondary then I would think you wouldn't cold crash until it has been in your primary for 4 weeks. Just my understanding.

 

[ongreystreet]

I've never cold crashed, but I have done a secondary, and I've seen the additional yeast on the bottom of my secondary. I'd be willing to bet you have a lot more drop off with a few more weeks in your bucket, primary or secondary, then with cold crashing. I am not saying cold crashing doesn't work, but I think sitting in the bucket is rough grit, cold crashing is the fine.

 

[TANSTAAFB]

What are you trying to get out of your beer through cold crashing that you feel you do not get by not cold crashing?

The biggest reason I have heard for cold crashing is to clear the beer by dropping solids out of solution. In my experience, more time in the primary at fermentation temps (or cooler after 2-3 weeks) results in the same clarity. In addition my yeast cake is very compact so I can actually vaccuum my beer off the cake. I feel that bulk conditioning in the fermenter takes less time than conditioning in the bottle, resulting in better, cleaner beer in less time. As soon as my beer is carbed it tastes great. I no longer have to wait for that "green" flavor to go away.

IMHO, brew a recipe you have cold crashed after 2 weeks, leave the beer in the primary for 3-4 weeks, skip the cold crash, and you decide if there is a difference. Please post your results as we would love to hear which method you feel produced the better beer and why

 

[rycov]

i usually cold crash after the beer has fermented and conditioned. so after about a month. it helps a little with the clearing and it gets the beer cold, so when i put it carbs a little faster in the keg. (i guess it would be slower in the bottles)

 

[aidan]

Looks like you all concur that the answer to my question in #7 is to leave it at fermentation temperature for the extra days in the primary instead of cold crashing it. That's the conclusion I was coming to myself.

I had started cold crashing from my very first batch because it was suggested to me on this forum on one of my first topics, about how to use gelatin finings, so I looked into it a bit more and decided to do it since I'm already brewing in a fridge. But from now on, backed up by the responses in this thread, I think I'll skip the cold crash and give it a little longer in the primary at fermentation temp instead.

 

[MalFet]

Don't have any specific links to point to, it was just stuff I read on this forum, i.e people's opinions, theorising, etc.

In any case one of the questions I'd like to hear some opinions on is, if I've fermented for 2 weeks in primary and I'm going to give it another 4 or 5 days in primary before bottling, am I better using that time for cold crashing or just leave it at fermentation temperature to continue conditioning process?

I think it would very much depend on the beer. Cold crashing to my mind is a way of speeding up the process of dropping solids (particularly yeast, but not only) out of suspension. If you can wait for those things to fall out at their own pace, then you're good. Some styles of beer and some types of yeast see this happen quicker than others. Rather than coming up with a hard rule, I think your best bet is to decide based on the situation. If your beer has cleared nicely 4-5 days before you want to bottle, then leave it at standard temps. If it hasn't, then decide if you are willing to wait another week or two. If not, crash cool.

 

[Wyrmwood]

That said, if you have any links pointing to the role of the yeast cake in conditioning I would love to read them.

https://www.homebrewtalk.com/f163/s...inasheff-weigh-176837/index3.html#post2049152
https://www.homebrewtalk.com/f163/s...inasheff-weigh-176837/index4.html#post2050533
https://www.homebrewtalk.com/f163/s...nasheff-weigh-176837/index10.html#post2087565

 

[MalFet]

https://www.homebrewtalk.com/f163/s...inasheff-weigh-176837/index3.html#post2049152
https://www.homebrewtalk.com/f163/s...inasheff-weigh-176837/index4.html#post2050533

I'm not sure what I should be looking for in those posts. Revvy talks about why skipping skipping secondary is a good thing, more or less repeating what JP and JZ say. I completely agree with it, but it isn't really a discussion of the role of the yeast cake. More a statement that long conditioning is good, transferring is unnecessary, and the yeast cake isn't harmful. I'd love to see something that says otherwise, but I haven't really seen much that suggests that the yeast cake plays an active role in aging or, say, that conical brewers should stop dumping their trub after krausen drops.

The beechwood stuff is interesting, but I have always been skeptical. It is strange, anyway, that A-B is the only brewery that still uses it. If the principle conditioning reactions were taking place at the point of contact between the liquid and sedimented yeast (as opposed to by yeast in suspension), I would imagine that we should all be beechwood aging.

 

[Wyrmwood]

I'm not sure what I should be looking for in those posts. ...

Secondly- when we talk about the "yeast cleaning up after themselves' we're talking about the yeast having plenty of time to go the extra mile and pull a lot more proteins and stuff out of solution which results in overall clarity. Think of it like polishing the beer molecules. The beer as a whole takes on a cleaner, and crisper flavor profile and overall visual clarity, including reducing chill haze proteins.

...most of us who have been leaving our beer in prmary for a month, ... that leaving our beer on the yeast for a month has led to a VAST improvement in our beers. In terms of clarity, in terms of clearing up those by products of fermentation, and in terms of an overall crispness to our beers. ...

It's mostly Revvy doing the "preaching", but it's a pretty long thread and there are some quoted industry folks making the same claims. Having said that, I'm finding Revvy about as trusted a source as any

 

[MalFet]

It's mostly Revvy doing the "preaching", but it's a pretty long thread and there are some quoted industry folks making the same claims. Having said that, I'm finding Revvy about as trusted a source as any

Not meaning to be stubborn here, but none of those quotes make any distinction whatsoever between yeast in suspension and yeast flocced down into the cake. I don't think anybody would dispute that suspended yeast are extremely important to conditioning beer, but that isn't what is being discussed here.

 

[earwig]

It's mostly Revvy doing the "preaching", but it's a pretty long thread and there are some quoted industry folks making the same claims. Having said that, I'm finding Revvy about as trusted a source as any

sorry bro, revvy is full of **** sometimes and will say anything to backup a claim he has made. He tried saying that he has sealed buckets with no leaks in them at all and only gets airlock activity 50% of the time... BS.

 

[user 19629]

This has all been beat to death and I keep telling myself I am going to ignore these type of threads, but I can't help it.

The AHA has an Ask The Experts on their website.
I asked White and JZ about the benefits of "extended primaries"
And their answer was pretty much "let the beer ferment, give it a couple of days to reabsorb diacytl etc. and then bottle or keg, there is no advantage to leaving it sit on the yeast cake for any longer.
I tried making some of these points in that other thread to no avail.
I was pretty much told I didn't know what I was talking about.
Doing a secondary is perfectly OK as long as you don't do it too soon.
Same with cold crashing.
I would think if you need weeks for the yeast to "clean up" you are doing something wrong. But if that's what it takes for your beer hey go for it.
Try different things see what works for you and your beer and have fun.
I say there are only to things that are mandatory in brewing.
1. good sanitation
2. RDWHAHB

 

[unionrdr]

Well,what I did on my 1st brew (with Cooper's lager kit),was to let it ferment towards the low end of the temp range(20C) till it cleared up to a slight haze at 12 days. Made sure the FG was steady,then primed & bottled. Cooper's & many others I've read say to condition the bottled beer at above 18C (about 68F) for at least 2 weeks. Carbonate & clean/clear up,ya know. After further reading of how some beers turned out,& even something Cooper's said,I'm letting them mature at cool room temp for 3 weeks,then into the fridge for a 4th week cold crash. I understood that to help it clear more,& make the small amount of hazy stuff firm up a lil more in the bottom of the bottle.

 

[boo boo]

I'll add my 2 cents here.

I think that removing the beer from the spent yeast makes for a better beer as among other things keeps the beer from fatty acids in the dead yeast that promotes a soapy flavour.
Leting the yeast keep doing what it is supposed to do while being in suspension can only help a beer. Crash cooling will drop out still active yeast that helps reduce diacetyl and further smooth out a young beer.
This has been preached by many worthy brewers over the years and as always, your results may vary.

 

[jeffmeh]

I was under the impression that you cold crash after secondary. That said if you don't secondary then I would think you wouldn't cold crash until it has been in your primary for 4 weeks. Just my understanding.

+1. Try giving more conditioning time at fermentation temp before you cold crash. I tend to go 4 weeks then cold crash for a week.

 

[MalFet]

This has all been beat to death and I keep telling myself I am going to ignore these type of threads, but I can't help it.

The AHA has an Ask The Experts on their website.
I asked White and JZ about the benefits of "extended primaries"
And their answer was pretty much "let the beer ferment, give it a couple of days to reabsorb diacytl etc. and then bottle or keg, there is no advantage to leaving it sit on the yeast cake for any longer.
I tried making some of these points in that other thread to no avail.
I was pretty much told I didn't know what I was talking about.
Doing a secondary is perfectly OK as long as you don't do it too soon.
Same with cold crashing.
I would think if you need weeks for the yeast to "clean up" you are doing something wrong. But if that's what it takes for your beer hey go for it.
Try different things see what works for you and your beer and have fun.
I say there are only to things that are mandatory in brewing.
1. good sanitation
2. RDWHAHB

You don't know what you are talking about...

I'm just kidding, of course. I certainly agree with you that it is far too simple to just say "all beers must be in primary for 37.2 weeks or they will taste like diaperjuice." At the same time, and with all respect, I think you are guilty here of the same sin of oversimplification. Beer changes as it ages; I don't think anyone would dispute that, right? Calling these changes "cleaning up" is certainly dumbing down the science involved, but there are a diversity of things that happen as beer sits: some metabolic processing, some inorganic chemical reactions, and some purely mechanical stuff as solids agglutinate and drop out of suspension.

There have been interesting discussions here and elsewhere about the relative benefits of bulk vs. bottle aging and about pre-carbonation and post-carbonation aging, but saying that beer is ready after two weeks or after twenty weeks just begs a definition of "ready". This sh!t is alive, yo.

The JPs, JZs, and CPs of the world are knowledgeable enough about their processes that they can turn around beer faster than I can. But I've also noticed with my own stuff that my beer gets better faster than it used to, and I'm sure that's all about better technique. That said, saying that if you need to age your beer you are doing it wrong is redonkulously simplistic. We're all "doing it wrong" to some degree, and all beer changes as it ages. The real skill is to develop a sensitivity to and vocabulary for these changes in order to better anticipate and control them.

 

[unionrdr]

Well,what I said,for instance,is a general consensus of what the companies/other more knowledgeable brewers say. They also said,letting it sit for 3 months or more in the bottle makes them even better. Of course,this would depend on the style. But in general,for the average beer to be considered good or good enough to try/drink,3-4 weeks is "minimum good".

 

[Yooper]

There is nothing "magical" about leaving the beer on the yeast after about 3-4 days after fermentation ends. There is also nothing "harmful" in leaving it on the yeast cake for 4 weeks or more, contrary to older advice. I've never left my beer in primary more than 3-4 weeks, so I can't speak with experience how long it will be before any hints of autolysis will begin for my beers but at 3 weeks, there certainly isn't any at that point.

The beer needs a bit of time, whether in primary or secondary. Leaving it in primary is simply a secondary without the yeast removed, when you think about it. The key is time to condition and clarify. Pro Breweries move the beer to the brite tank- to give it some time, to be able to start a new batch in the fermenter, and sometimes to carbonate. Nothing magical about moving it, really, since the yeast is dropped from the fermenter when needed.

I also want to be clear that I'm talking about ales here, and ale temperatures.

Remember that beer ages faster at warmer temperatures, so if the beer needs some time it's best to do that at a warmer temperature. Once the beer is ready, cold crashing will help it clear. I don't see a benefit to cold crashing a beer longer than a couple of days, unless you're trying to get rid of chill haze which may take a couple of weeks.

My preference has been to treat lagers a bit differently- still racking after the diaceytl rest and a relatively short primary.

My ales are usually in the fermenter for 2 weeks, but I've gone as long as three.

 

[remilard]

The AHA has an Ask The Experts on their website.
I asked White and JZ about the benefits of "extended primaries"
And their answer was pretty much "let the beer ferment, give it a couple of days to reabsorb diacytl etc. and then bottle or keg, there is no advantage to leaving it sit on the yeast cake for any longer.
I tried making some of these points in that other thread to no avail.

There are certain points that can't be made in certain parts of the internet. My process is consistent with the above but I've stopped advocating for it here.

 

[user 19629]

>>>>>>>>>> I think you are guilty here of the same sin of oversimplification. Beer changes as it ages; I don't think anyone would dispute that, right? Calling these changes "cleaning up" is certainly dumbing down the science involved, but there are a diversity of things that happen as beer sits: some metabolic processing, some inorganic chemical reactions, and some purely mechanical stuff as solids agglutinate and drop out of suspension.
>>>>>>>>>> That said, saying that if you need to age your beer you are doing it wrong is redonkulously simplistic. We're all "doing it wrong" to some degree, and all beer changes as it ages. The real skill is to develop a sensitivity to and vocabulary for these changes in order to better anticipate and control them.

I can accept that, guilty as charged
and for me to say:
"I would think if you need weeks for the yeast to "clean up" you are doing something wrong. But if that's what it takes for your beer hey go for it."
was a bit reactionary what I should have said was:
" If your beer is better leaving for several weeks to "clean up " that's great keep on doing what your doing."

 

[Chad]

And this is one of the reasons to drink your hydrometer samples. I brew a lot of moderate gravity beers -- 1.038 to 1.050 -- and ferment cool. Rarely does actual fermentation take more than a week to 10 days. Another couple of days on the yeast is always a good thing to allow the yeast to process diacetyl and other fermentation products. After that, if I don't taste anything weird in the fermentor, the beer goes in the fridge to drop clear for a couple of days and then is kegged and carbed. In all, I usually go 12-14 days at fermentation temps plus 2-3 days in the fridge. My last beer followed this fermentation schedule and took first in English Ales at a regional competition.

I used to leave my beer on the yeast for weeks and weeks, and I'm certainly not afraid to do so, but for session beers (what I brew) I don't find it necessary. As somebody quoted JZ and JP above, all you need is a couple of days of cleanup, usually at a slightly elevated temperature. I take my bucket or carboy out of its water bath & let it rise to low room temp.

If you make higher gravity beers or have to ferment at the high end of the yeast's temperature range, by all means let it clean up as long as necessary. I do the same if I taste diacetyl or other off flavors. But for the most part if you have control of your fermentation temperatures it's not necessary for moderate gravity beers.

 

[unionrdr]

That was pretty much my thoughts on the fermenter stage. My last one took 12 days. If this one takes only 7 or 8,so be it. Just let it stay long enough to clear to a slight haze,& I'm good. Usually there by FG time anyway. Congrats on the victories! I'd like to do that with this brew,but we'll see how this 1st version of the recipe goes...

 

[Bobby_M]

The way I look at it is if your beer requires extended warm conditioning, it's because there was something problematic in the primary fermentation already. Elevated diacytel for example. If you've already got a nice clean ferment that is throughly completed with no real biproducts (fusels) then it's time to get the beer clear and start drinking. My impression is that most of what people call "green" flavors in beer is due to suspended yeast and other particulates. To test this theory, take two beers that have been bottle conditioned and have sat undisturbed in a fridge for 2 weeks. Gently swirl and invert one of them a few times, let it sit for 5 minutes, then pour both. The one with junk swirled in reminds me of young beer. Commercial guys can accomplish this by filtering or homebrewers can do it by cold crashing or extended warm aging. Of course this is just my opinion on the matter. My cold crashed beers are always drinkable sooner and I don't feel like I'm sacrificing quality at all.