[Nagel Family Brewing]

I am curious as to the science behind crash cooling a beer.  When you crash cool are you permantly precipitating out compounds that won't resuspend if the beer warms back up.  I am assuming that the yeast that floc to the bottom during crash cooling would resuspend into solution if the beer warms back up.  Is this a correct assumption?  What about other compounds that precipitate out during crash cooling.  What are they and will they resuspend if the beer is warmed back up?
Thanks,
Ryan

[Thirsty_Monk]

If you listen Brew Strong with Dr. Bamforth he talked a little bit about it (and other things).

When you cold condition your beer small particles like haze will drop down.
It is better cold condition at 32F for just a few days then at 36F for couple of weeks.

http://thebrewingnetwork.com/shows/572
http://www.thebrewingnetwork.com/membersarchive/bs_haze110309.mp3

[Nagel Family Brewing]

If you listen Brew Strong with Dr. Bamforth he talked a little bit about it (and other things).

When you cold condition your beer small particles like haze will drop down.
It is better cold condition at 32F for just a few days then at 36F for couple of weeks.

http://thebrewingnetwork.com/shows/572
http://www.thebrewingnetwork.com/membersarchive/bs_haze110309.mp3

I think I listened to that.  I am curious as to what happens though if the beer is crash cooled but then warms back up before transferring?  I don't remember that coming up on Brew Strong.

[Thirsty_Monk]

You should transfer the cold beer because if you worm it up some "chill" haze might return.
That also goes if you filter your beer.
You want to leave all the "gunk" (technical term) in the first vessel.

[Nagel Family Brewing]

You should transfer the cold beer because if you worm it up some "chill" haze might return.
That also goes if you filter your beer.
You want to leave all the "gunk" (technical term) in the first vessel.

Yeah, I understand I want to do that.  I am just curious of the science behind it and what happens when the beer warms up.  I am curious what is permanently flocculating and what is temporarily flocculating. 

[Kaiser]

The chill haze is formed by hydrogen bonds between tannins and the proline rich regions of proteins. Proline is a particularly hydrophobic (water hating) amino acids and typical for haze forming proteins. So typical in fact that some fining agents are able to use that property of haze forming proteins to selectively remove them while keeping the foam positive proteins in the beer.

As more and more proteins link with tannins the blob grows lager and larger and eventually precipitates and settles to the bottom. But since these bonds are very weak, an increase in the thermal energy in the beer (i.e. temperature increase) can easily break them and the blobs disintegrate and go back into solution. As a result the colder the beer the more bonds will form and the larger the blobs will become.

If the heating and cooling cycle repeats the bonds can get stronger and eventually so strong that warming the beer doesn’t break them and won’t re-dissolve the haze. At this point you have a permanent haze. We don’t really get this as we don’t abuse our beer as much.

To efficiently remove chill haze from a beer you need to chill it as cold as possible w/o freezing it (29-30F), let the haze settle and rack the cold beer off the sediment. You may also filter. But I feel that lagering the beer long enough is less hassle than setting up a filter.

Kai

[Nagel Family Brewing]

Perfect.  Thanks.

[dimik]

I cold crash in a keg and suck out the sediment.

[Kaiser]

I cold crash in a keg and suck out the sediment.

I don't think that you can suck out all the sediment in a keg. The sides of the bottom are not steep enough for all the sediment to slide towards the dip tube.

Kai

[dimik]

I don't know. After keeping it cold for a week or two, I suck it out and the beer is clean and clear, however when the keg is about to kick, some yeast appears (guess they must be on the sides or something)

[Kaiser]

I don't know. After keeping it cold for a week or two, I suck it out and the beer is clean and clear, however when the keg is about to kick, some yeast appears (guess they must be on the sides or something)

What you are making is a small area around the dip tube that is free of sediment. The bottom is still filled with sediment but it won't move until the beer level is low enough that it starts to wash the sediment down. This is when the keg goes empty. As a result the last and the first few glasses are the cloudy ones.

There may not be a problem with that. Especially if you don't move the keg around. I just prefer to rack the beer off the sediment into a new keg.

Kai

[dimik]

Sounds good. You're more experienced than I am, so I'll heed your advice

[narcout]

I am assuming that the yeast that floc to the bottom during crash cooling would resuspend into solution if the beer warms back up.  Is this a correct assumption?

Once the yeast drops out of suspension, I think it tends to stay there unless you agitate it.

To efficiently remove chill haze from a beer you need to chill it as cold as possible w/o freezing it (29-30F), let the haze settle and rack the cold beer off the sediment.

I find that this usually takes around 3 weeks or so for me, but my kegerator is set at 37 degrees. Do you find that keeping it colder speeds up this process?

[narcout]

I don't know. After keeping it cold for a week or two, I suck it out and the beer is clean and clear, however when the keg is about to kick, some yeast appears (guess they must be on the sides or something)

That's been my experience as well.

I usually crash cool the primary to 32 degrees for 2 or 3 days, then rack off the sediment into a keg. Then I stick that in the kegerator and carbonate/cold condition for several weeks. Most of the additional crud that drops out during that time comes out in the first few ounces, then it pours clear (of both yeast and chill haze) until the last pint (by which I mean the last pint has some sediment in it).

[stout_fan]

The problem with crash cooling is some folks do it too soon. The yeast consumes the diacetyl it produces last.
Putting the yeasties to sleep too early can have bad consequences.
Let the little guys finish their job first.