Cold Crashing??

[brentt03]

Probably a dumb question, but I am going to ask it anyways

So, I have a brew in the fermenter, and I plan on cold crashing this one. Now I have read that you need to cold crash 24-48 hours before bottling.

Is there an ideal temperature for cold crashing??

And lets say you cold crash for 48 hours, do you just let the brew warm back up to room temp and then bottle it????

 

[flabyboy]

I just cold crashed for 2 days in 40 degree garage. Bottled at cold temps. Brought bottles into my 70 degree room to condition. It looked really clear coming into the bottling bucket

 

[skyebrewing]

Ive cold crashed for a couple weeks in a fridge set to high thirties before with no problems. Bottle as usual and get them to a place around 70 degrees. Check in three weeks and you'll be on your way to tasty beer

 

[Bizoune]

I cold crash for 48 hours then bottle. Works fine. There's a lot of CO2 in solution when the beer is colder so you end up with lest sugar added to you're bucket to get the volume of carbonation that you're looking for.

 

[brentt03]

I cold crash for 48 hours then bottle. Works fine. There's a lot of CO2 in solution when the beer is colder so you end up with lest sugar added to you're bucket to get the volume of carbonation that you're looking for.

How do you calculate the amount of sugar needed post cold crashing?? Is it not just the same as if you don't cold crash? Sorry, this is just new to me.

 

[Bizoune]

I use this handy calculator everytime i bottle.

http://hbd.org/cgi-bin/recipator/recipator/carbonation.html

You just need to figure out your beer temp/volume and how much volume of C02 you're shooting for. The calculator tells you how much sugar to add to your bottling bucket.

 

[schmaltzy]

Removed post because I did want to hijack this thread!

 

[Bru]

My understanding is when calculating the amount of sugar required one should use the highest temp the beer has been once fermentation has finished (and no longer producing CO2) not the temp of the beer at the time of bottling.

 

[Bizoune]

My understanding is when calculating the amount of sugar required one should use the highest temp the beer has been once fermentation has finished (and no longer producing CO2) not the temp of the beer at the time of bottling.

Really? I'd love to read up more on this. I've been adding my sugar in function of beer temp at time of bottling and results seem to be in line with volumes of C02 I'm looking for.

 

[WildGingerBrewing]

My understanding is when calculating the amount of sugar required one should use the highest temp the beer has been once fermentation has finished (and no longer producing CO2) not the temp of the beer at the time of bottling.

I've never heard this either. I always thought the amount of sugar added was based on the temp of the beer when bottling.

And back to the OP, I cold crash down to about 34-36F for a week or so, then let the beer sit at room temp for a few hours on bottling day to bring it back up. I could use the calculator mentioned above and use less priming sugar, I have just never done it. I find that by the time I am ready to bottle (cleaned, sanitized, etc...) the beer is pretty close to room temp anyway.

 

[CTS]

Sorry for my ignorance but what is the purpose behind cold crashing?

 

[vitrael]

Sorry for my ignorance but what is the purpose behind cold crashing?

It causes stuff in suspension, mostly yeast and protein, to precipitate into sediment, resulting in a clearer finished beer.

 

[CTS]

It causes stuff in suspension, mostly yeast and protein, to precipitate into sediment, resulting in a clearer finished beer.

Kinda what I thought, thanks for clearing that up!

 

[Veinman]

I'm trying to work through the science of the priming sugar question.
My thinking is as follows:
You have a beer that was fermented at 65F that is done fermenting since its sitting at 65F it has "x" CO2 in it that being the max amount of CO2 beer can hold at 65F. You cold crash it to 40F now the beer has the capability of holding more CO2 but in order to have more CO2 enter the beer CO2 must come from somewhere. I suppose the CO2 blanket in the neck of the carboy could be absorbed back into the beer much like happens in bottle conditioning. But what if you don't have a very big CO2 blanket because you moved to secondary or you have very little headspace in your carboy.

This leads me to believe you should use the highest temperature the beer has been at since fermentation was complete but I'm not totally and am open to hearing why the opposite might be true.

 

[sudsmcgee]

Kinda what I thought, thanks for clearing that up!

So, in a way, you just got cold crashed.

 

[BWN]

At what temp. will beer freeze, and is it bad if it does?

 

[brentt03]

Just thinking out loud, but I would think priming sugar amount would be based off of the beer's temp at bottling time...but some good discussion going on here!

 

[flabyboy]

Just thinking out loud, but I would think priming sugar amount would be based off of the beer's temp at bottling time...but some good discussion going on here!

From what I was told, its actually the opposite. Use the highest temp during fermentation to determine your priming sugar weight

 

[Bru]

You will probably find that the temp at bottling time is very similair to the highest temp since fermentation was complete or at least very close to it.

This is one of those debatable topics but my understanding is like this :
as we know its fermentation that produces CO2 therefore once fermentation is complete no further CO2 wil be produced. From that point its temerature that determines how much CO2 will remain in the beer. If temperature increases the CO2 will be released and cannot be replaced (as fermentation is finished).
Likewise if temp drops the beer will only absorb CO2 that remains. If its been helluvu hot there won't be much left to absorb.
Thats why I think it makes sense to use the highest temp since fermentation completes.
I'd like to hear what others think.

Really? I'd love to read up more on this. I've been adding my sugar in function of beer temp at time of bottling and results seem to be in line with volumes of C02 I'm looking for.

 

[Frodo]

I've only read that it's the temp at time of bottling that matters, but I've wondered it that's true.

In a vacuum, if a beer that was at equilibrium was cooled from 65F to 38F it would be "starved" of dissolved gas. It would be willing to accept more gas into solution but there wouldn't be any. I doubt the beer cares whether it's CO2 gas or not. However we don't ferment in a vacuum (well I don't anyway). So if I took a carboy of beer (completely fermented) at 65F, who's max fermentation temp was 68F, and stuck it in the fridge at 38F, it would start absorbing gas from the headspace. When the headspace pressure was low enough due to gas absorption to overcome the gravity of the fluid in the airlock, wouldn't it suck the airlock fluid in and eventually get the gas it desires from the air in the fridge?

EDIT: I was wondering though, if that is true, would cold crashing then be causing oxidation? I've never cold-crashed, so have no experience with it by the way; just thinking through the physics.

 

[straylight77]

So if I took a carboy of beer (completely fermented) at 65F, who's max fermentation temp was 68F, and stuck it in the fridge at 38F, it would start absorbing gas from the headspace. When the headspace pressure was low enough due to gas absorption to overcome the gravity of the fluid in the airlock, wouldn't it suck the airlock fluid in and eventually get the gas it desires from the air in the fridge?

I think there are a couple of other factors that lead to pressure drop in the fermentor where the fluid in the airlock gets sucked in. Any drop in temperature would reduce the pressure of a gas (Ideal Gas Law). It may not be getting dissolved into the beer, it's just taking up less space because of the temp drop (think expansion and contraction of solids when the temp changes). I think that's where most of the effect of getting airlock fluid sucked in comes from.

Furthermore, I would think that, in order to get more CO2 dissolved into the beer you would need to increase the pressure. Most of CO2 has already escaped form the higher temperatures during fermentation. Once it reaches that state of equilibrium, combined with the pressure drop from the temperature, there wouldn't be enough force (pressure, mass, etc) to "push" it the solution.

Although, I'll admit my knowledge of the solubility of gases in a liquid is a bit limited. Someone please correct me if I'm wrong on these points...

 

[Frodo]

I think there are a couple of other factors that lead to pressure drop in the fermentor where the fluid in the airlock gets sucked in. Any drop in temperature would reduce the pressure of a gas (Ideal Gas Law). It may not be getting dissolved into the beer, it's just taking up less space because of the temp drop (think expansion and contraction of solids when the temp changes). I think that's where most of the effect of getting airlock fluid sucked in comes from.

I was just thinking through the gas equilibrium part, but I would definitely agree that reduction in temperature should cause a much larger reduction in pressure in the fermenter than any gas absorption could cause. When cold crashing, do people put sealed bungs on their carboys to prevent air being pulled in? Or only use sealed kegs?

 

[straylight77]

From what I've read on these forums people just move their fermentor to the fridge (or wherever). It's expected that a bit of liquid from the airlock will get into the beer -- which is why you need to use something where that's okay (i.e. vodka, star san, NOT bleach, etc).

I haven't actually done a cold crash yet but I'm hoping to for my next brew. So it's timely this has come up, specifically when it comes to how it affects the amount of priming sugar we should use.

 

[schmaltzy]

To kind of piggy back on straylight77's question.....if using star san, should you put new stuff in before cold crashing?

The star san I used in my airlock for fermenting is looking pretty hazy, is this still ok if it gets sucked in?

 

[Yooper]

I'm trying to work through the science of the priming sugar question.
My thinking is as follows:
You have a beer that was fermented at 65F that is done fermenting since its sitting at 65F it has "x" CO2 in it that being the max amount of CO2 beer can hold at 65F. You cold crash it to 40F now the beer has the capability of holding more CO2 but in order to have more CO2 enter the beer CO2 must come from somewhere. I suppose the CO2 blanket in the neck of the carboy could be absorbed back into the beer much like happens in bottle conditioning. But what if you don't have a very big CO2 blanket because you moved to secondary or you have very little headspace in your carboy.

This leads me to believe you should use the highest temperature the beer has been at since fermentation was complete but I'm not totally and am open to hearing why the opposite might be true.

I've only read that it's the temp at time of bottling that matters, but I've wondered it that's true.

In a vacuum, if a beer that was at equilibrium was cooled from 65F to 38F it would be "starved" of dissolved gas. It would be willing to accept more gas into solution but there wouldn't be any. I doubt the beer cares whether it's CO2 gas or not. However we don't ferment in a vacuum (well I don't anyway). So if I took a carboy of beer (completely fermented) at 65F, who's max fermentation temp was 68F, and stuck it in the fridge at 38F, it would start absorbing gas from the headspace. When the headspace pressure was low enough due to gas absorption to overcome the gravity of the fluid in the airlock, wouldn't it suck the airlock fluid in and eventually get the gas it desires from the air in the fridge?

EDIT: I was wondering though, if that is true, would cold crashing then be causing oxidation? I've never cold-crashed, so have no experience with it by the way; just thinking through the physics.

The first post is correct- more co2 isn't produced after fermentation is over, so you don't go by the current beer temperature for priming calculations. As we all know, more co2 is released at warmer temperatures so you use the highest temperature the beer was at after fermentation, or right before it ended.

If your airlock sucked in all the liquid from the airlock, I suppose it is true that oxygen/air would be sucked in once the liquid is gone. That's why you don't want an empty airlock.

 

[RandalG]

So I 'm kegging my first batch of Jamil's Evil Twin in a few weeks and was thinking about cold crashing it first. So do I just lower the temp in the chest freezer the last few days of secondary to the upper 30's than rack into a keg and stick it in the kegerator set at the serving temp. I wasn't sure if the process is different as I'll be force carbing not bottling.

 

[Yooper]

So I 'm kegging my first batch of Jamil's Evil Twin in a few weeks and was thinking about cold crashing it first. So do I just lower the temp in the chest freezer the last few days of secondary to the upper 30's than rack into a keg and stick it in the kegerator set at the serving temp. I wasn't sure if the process is different as I'll be force carbing not bottling.

You can do that, of course, and many people do. I'm a lazy short, so I keg first. Then stick the keg in the kegerator, which is a cold crash. One step, same results.

 

[Bizoune]

So I 'm kegging my first batch of Jamil's Evil Twin in a few weeks and was thinking about cold crashing it first. So do I just lower the temp in the chest freezer the last few days of secondary to the upper 30's than rack into a keg and stick it in the kegerator set at the serving temp. I wasn't sure if the process is different as I'll be force carbing not bottling.

This is exactly what I do. Cold crash for 48 hours then off to the keg it goes. 12PSI for 7 days = Bingo! Perfectly carbed homebrew.

 

[Redpiper]

Here is quite a lengthy thread on the sugar/temp question:
https://www.homebrewtalk.com/f128/effects-cold-crashing-priming-sugar-needs-134347/

As I recall, interesting thread and the answers varied. I have gone (as have many earlier in this post) with the highest fermenting temp. I cold crash 2-3 days and then bottle cold. The carbonation has worked out perfectly. The pale ales are higher and nicely carbed, the stouts and IPA's lower, more gently carbed.

In other words, my results in practice support the idea that you use the highest temp achieved during fermenting (actually I use the dominant temp - i.e. was mostly 68 but hit 70 once, I use 68).

 

[h22lude]

I have a Belgian Wit about to be bottled. It is around 1.015 right now and I brewed it 3 weeks ago. I want to try to make it less cloudy so I think this one I will cold crash. I also have a golden ale that is almost 2 weeks that I might try to use gelatin just to see the difference but that is another topic.

Anyway, I have a kegerator that I can cold crash at a low temp (high 30s to low 40s). I will do that for 2 days. I like to bottle in my kitchen so I will probably move my fermenter to the kitchen to bottle. I would assume it would take a long time for the beer to get to room temp. Using that calculator...Belgian Wit desired CO2 around 2.2, bottling 5 gallons, highest temp around 68 using corn sugar I would use 3.59 oz.

Sound about right to everyone?