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Old 07-15-2012, 01:48 PM   #1
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Default cold-conditioning vs warm conditioning - what is the science?

I'm trying to understand what is happening when we condition our beers. We all know lagers must be lagered - that month or three just above freezing really drives off those sulphur compounds and makes the beer "come together". The yeast are not active at these temperatures.

But we also bottle-condition and store other beers at room temperature. We rely on yeast in suspension to consume off-flavors as well as carbonate the beer.

We know that cool cellaring preserves the character of big, malty beers for long periods.

So when is the right time to cold-condition (30's) cellar (50's) or warm-condition (60's)? Does it depend on the beer? Would it be better to give every beer ~2 weeks warm, then cold crash for 2-4 weeks of lagering?

What is the chemistry happening during lagering and aging, and how can we take advantage of it?

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Old 07-27-2012, 05:11 PM   #2
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Ok I'll take a stab at this. The difference between conditioning and lagering, from my understanding, are 2 worlds apart. For instance if you have a beer that is ending the primary fermentation you increase the temperature, in ales and lagers, for the diacetyl rest to let the yeast absorb the diactyl. From here often the beers are chilled to near 32 degrees for a few days to have the majority of the yeast biomass drop out of solution.
This is where the 2 differ. At a brewery I once worked at, for lagers, we transfered the Lager beer to a lagering tank where the yeast that was still in suspension cleaned up the sulfers and off flavors produced by that yeast before being sent to the filter. On average this lagering took 4-6 weeks.

In ales, after cold crashing, the beers were sent to filtration then to packaging. Now at this stage the beers needs time to mature which means time is given to allow all the flavors to blend together and become stable while sitting in the cold room at near 32 degrees. On the other side of things when doing cask ale or bottle conditioned, which more resembles homebrew processes, after cold crashing the beer still has enough yeast in suspension (even though it may look bright) to carbonate the beer using sugars (table sugar, brown sugar, fermenting wort, and so on). When doing this the packaged beer must be warmed up and stay at the fermenting temperature of that yeast strain to condition or allow the yeast to ferment the sugars creating the proper CO2 levels needed. This is the conditioning stage that usually lasts about a week before dropping the temperature to around 32 degrees to the maturing stage. If doing lagers after the lagering stage the beer is pitched with priming sugar and let to condition just as ales then sent to the maturing stage. If force carbonating then there is no need or use for conditioning stage and goes straight to maturing stage.

So it depends on the time, intent, and desired outcome of your temperature rest that dictates if you are doing a diacetyl rest, lagering, conditioning, or maturing a beer. I hope this is on topic of what you are looking for.

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Old 07-27-2012, 05:26 PM   #3
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Ok I'll take a stab at this. The difference between conditioning and lagering, from my understanding, are 2 worlds apart. For instance if you have a beer that is ending the primary fermentation you increase the temperature, in ales and lagers, for the diacetyl rest to let the yeast absorb the diactyl. From here often the beers are chilled to near 32 degrees for a few days to have the majority of the yeast biomass drop out of solution.
This is where the 2 differ. At a brewery I once worked at, for lagers, we transfered the Lager beer to a lagering tank where the yeast that was still in suspension cleaned up the sulfers and off flavors produced by that yeast before being sent to the filter. On average this lagering took 4-6 weeks.

In ales, after cold crashing, the beers were sent to filtration then to packaging. Now at this stage the beers needs time to mature which means time is given to allow all the flavors to blend together and become stable while sitting in the cold room at near 32 degrees. On the other side of things when doing cask ale or bottle conditioned, which more resembles homebrew processes, after cold crashing the beer still has enough yeast in suspension (even though it may look bright) to carbonate the beer using sugars (table sugar, brown sugar, fermenting wort, and so on). When doing this the packaged beer must be warmed up and stay at the fermenting temperature of that yeast strain to condition or allow the yeast to ferment the sugars creating the proper CO2 levels needed. This is the conditioning stage that usually lasts about a week before dropping the temperature to around 32 degrees to the maturing stage. If doing lagers after the lagering stage the beer is pitched with priming sugar and let to condition just as ales then sent to the maturing stage. If force carbonating then there is no need or use for conditioning stage and goes straight to maturing stage.

So it depends on the time, intent, and desired outcome of your temperature rest that dictates if you are doing a diacetyl rest, lagering, conditioning, or maturing a beer. I hope this is on topic of what you are looking for.

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Old 07-27-2012, 08:55 PM   #4
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On the other side of things when doing cask ale or bottle conditioned, which more resembles homebrew processes, after cold crashing the beer still has enough yeast in suspension (even though it may look bright) to carbonate the beer using sugars (table sugar, brown sugar, fermenting wort, and so on). When doing this the packaged beer must be warmed up and stay at the fermenting temperature of that yeast strain to condition or allow the yeast to ferment the sugars creating the proper CO2 levels needed. This is the conditioning stage that usually lasts about a week before dropping the temperature to around 32 degrees to the maturing stage.
It sounds very interesting to me , since I also bottle condition my ales at home .

But , you separated "Conditioning" from "Maturing" !

It's been told and written several times by several Threads in "HBT" that we prime and bottle the "Green" Beer , so that it will be

carbed and matured simultaneously in the bottle at room temperature and it takes much longer than just one Week .

Now , you are saying that it should be kept in the bottle at room temperature for ONLY one Week in order to be carbed ( Conditioning ) and

then dropping the temperature to 32 F to begin the maturing stage .

Would you please make it clear for me .

Have we as home brewers done it always wrong ?!

Is it really so , that maturing takes place at such a cold temperature ?!

Hector
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Old 07-27-2012, 10:35 PM   #5
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Originally Posted by hector

It sounds very interesting to me , since I also bottle condition my ales at home .

But , you separated "Conditioning" from "Maturing" !

It's been told and written several times by several Threads in "HBT" that we prime and bottle the "Green" Beer , so that it will be

carbed and matured simultaneously in the bottle at room temperature and it takes much longer than just one Week .

Now , you are saying that it should be kept in the bottle at room temperature for ONLY one Week in order to be carbed ( Conditioning ) and

then dropping the temperature to 32 F to begin the maturing stage .

Would you please make it clear for me .

Have we as home brewers done it always wrong ?!

Is it really so , that maturing takes place at such a cold temperature ?!

Hector
I guess that technically while carbonating the maturing process also starts but also continues once the temperature has dropped. About carbonating beer it usually only takes 7-10 days depending on style, gravities and other factors. It is not a standard week for all beers but often close to it depending on these factors. I don't see why this would be hard to believe when you are only fermenting a very small portion of sugars to create a few volumes of carbon dioxide and the original primary fermentation is often completed in the same amount of time (give or take a day or 2).

Now while at the brewery after the given time to condition, or referment (~7-10 days), the casks went to the cold stoarge room (~32 degreeF) where it was given time to mature. Obviously some styles may require longer time at each step. From what I've been told and read maturing is the time that is given to let the compounds in the beer to stabilize and flavors mold together not the time it takes to carbonate a beer. This can happen at any temperature but we did it at a lower temperature to help slow down any oxidation and staling,properties that may occur in the normal process of beer.

I have not been here on HBT all too long and have not seen the posts that you mention but they differ from what I've been taught and practice. I have read a lot of posts and topics here and you folks are have a wealth of knowledge and am interested in any science background that supports that conditioning and maturing are the samething but with everything that I've been taught and the results shown in process that I have experienced I would have to respectfully disagree.
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Old 07-27-2012, 10:54 PM   #6
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Originally Posted by blacksailj View Post
Ok I'll take a stab at this. The difference between conditioning and lagering, from my understanding, are 2 worlds apart. For instance if you have a beer that is ending the primary fermentation you increase the temperature, in ales and lagers, for the diacetyl rest to let the yeast absorb the diactyl. From here often the beers are chilled to near 32 degrees for a few days to have the majority of the yeast biomass drop out of solution.
This is where the 2 differ. At a brewery I once worked at, for lagers, we transfered the Lager beer to a lagering tank where the yeast that was still in suspension cleaned up the sulfers and off flavors produced by that yeast before being sent to the filter. On average this lagering took 4-6 weeks.

In ales, after cold crashing, the beers were sent to filtration then to packaging. Now at this stage the beers needs time to mature which means time is given to allow all the flavors to blend together and become stable while sitting in the cold room at near 32 degrees. On the other side of things when doing cask ale or bottle conditioned, which more resembles homebrew processes, after cold crashing the beer still has enough yeast in suspension (even though it may look bright) to carbonate the beer using sugars (table sugar, brown sugar, fermenting wort, and so on). When doing this the packaged beer must be warmed up and stay at the fermenting temperature of that yeast strain to condition or allow the yeast to ferment the sugars creating the proper CO2 levels needed. This is the conditioning stage that usually lasts about a week before dropping the temperature to around 32 degrees to the maturing stage. If doing lagers after the lagering stage the beer is pitched with priming sugar and let to condition just as ales then sent to the maturing stage. If force carbonating then there is no need or use for conditioning stage and goes straight to maturing stage.

So it depends on the time, intent, and desired outcome of your temperature rest that dictates if you are doing a diacetyl rest, lagering, conditioning, or maturing a beer. I hope this is on topic of what you are looking for.
excellent post and exactly what I was looking for - thank you

I'm also interested to note the distinction between d-rest, lagering, conditioning and maturing - we often use some of these terms interchangeably

in your opinion maturing does not depend on having any yeast in suspension, while the other processes do?

also since lager beers produce undesirable sulfurs, while ales can produce undesirable fusels, esters, and phenols, do we know that yeast is more efficient at removing sulfurs at cold temps, and the other off-flavors at warm temps?
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Old 07-27-2012, 10:59 PM   #7
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I have not been here on HBT all too long and have not seen the posts that you mention but they differ from what I've been taught and practice. I have read a lot of posts and topics here and you folks are have a wealth of knowledge and am interested in any science background that supports that conditioning and maturing are the samething but with everything that I've been taught and the results shown in process that I have experienced I would have to respectfully disagree.
Please take a look at post #8 of this Thread and tell me your Opinion about it :

http://www.homebrewtalk.com/f35/bott...2/#post1030387

Hector
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Old 07-27-2012, 11:16 PM   #8
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I don't see why this would be hard to believe when you are only fermenting a very small portion of sugars to create a few volumes of carbon dioxide and the original primary fermentation is often completed in the same amount of time (give or take a day or 2).
By the time of Primary fermentation , there are lots of minerals and nutrients that the yeasties would love to consume .
That means the yeast cells are under 0% stress and they do their job well .

But , after bottling they are in an environment with less nutrients and more Alcohol .
That means they are under Stress and need more time to do their job as well as the Primary time .

Hector
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Old 07-27-2012, 11:30 PM   #9
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I was just reading a section in the book Malting and Brewing Science: Hopped Wort and Beer, Volume 2 about this and they mainly talk about lagers but it still applies to ales. The maturing does happen at fermenting temperatures until the yeast is completed carbonation and continues to stabilize the compounds during the aging stage which I always refered to as maturing stage. I believe this might be where we had a misunderstanding. I read that post you linked and it was very well written and I do agree. Most of the beers that I have worked with are of average gravities and roughly 5.5%abv. With this we never had the need to condition or mature for 3+ weeks although if doing a more intense brew that time most likely would be needed, and as mentioned of doing a barley wine it could take up to a year. Yes the yeast are under more stress but you are only fermenting a small portion of yeast and in average beers carbonation should be complete within 7-10 days. During the aging (what I concidered maturing stage) the flavors still continue to blend even at colder temperatures.

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Old 07-27-2012, 11:37 PM   #10
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I'm also interested to note the distinction between d-rest, lagering, conditioning and maturing - we often use some of these terms interchangeably
A diacetyl rest is raising the temperature of the fermentation near the end of the active fermentation in order to encourage the yeast to remain active and digest their own waste products (like diacetyl).

I highly recommend Kai Troester's website braukaiser.com if you like "geeky" scientific explanations for most things. I love it.

Here's an explanation of lagering, for example:
When the beer is conditioned at low temperatures various processes take place that lead to the smooth character which is expected from a lager:
Proteins and polyphenols (tannins) form agglomerations (basically bind with each other to form larger molecules) which become insoluble and precipitate out of solution. [Nguyen 2007]
Hop polyphenols will drop out leading to milder hop bitterness
Yeast sediment which cleans up the beer and removes the yeasty smell and taste associated with young beer
Some of the alcohols and acids form esters in the beer which leads to new flavor compounds. This process is very slow and becomes only significant after more than 12 weeks [Narziss 2005].
Some yeast activity may be present which leads to further clean-up and extract reduction of the beer. I oftentimes see another extract drop of 0.1 - 0.2 Plato over the course of a few weeks.

__________________________________________________ ____________

Conditioning and maturation are the same thing. Lagering is also a form of conditioning, but done cold usually following a fermentation by lager yeast.

The reason a lager tastes so much "cleaner" and "crisper" than an ale is usually due to the first reason listed above- the polyphenols are dropped out and the beer becomes smoother and crisp.
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