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Does the yeast do any "clean up" after FG is reached?

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kiwipen

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I've heard conflicting statements about this. Some say that when FG is reached and stable the yeast is done working, and the yeast itself wont to anything positively to the flavor. Others say that the yeast clean up off flavors at that point.
 

davidabcd

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I've heard the same. I picked a middle ground by leaving the beer in the fermenter for three weeks. Granted, all of my beers are high ABVs.
I think if you experiment (bottling/kegging at different intervals), you can confirm for yourself the best way for you.
Smaller beers finish often in three days so leaving the beer in the fermenter for one or two weeks is letting the yeast clean up and condition.
Edit: I have no scientific facts to back up my reply, just experience.
 

JohnSand

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I've also heard both views, and I guess it depends. Certainly the term "green beer" meant young beer that wasn't ready, and I've tasted that. I also leave mine in the fermenter for three weeks. Sometimes big beers, Belgian beers and spiced beer can take months to reach maturity, though I think that is not the yeast working, but other chemical processes.
 

CascadesBrewer

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My understanding mostly comes from writings of people smarter than me. My general practice is to give the beer enough time for fermentation to complete and the yeast to mostly settle out, which should give enough time for the yeast to "clean up". For most ales this is done in a 2 week fermentation cycle, but longer for higher gravity beers and some yeasts. Now that I have a fermentation chamber, I often start fermentation in the 64F to 66F range, then as fermentation slows (maybe day 4) I boost temps up to 68F to 72F for the remainder.

The online "How to Brew" is dated, but this description seems to match what I recall from the latest edition. It points at "clean up" occurring at the point where yeast have run out of sugars and are preparing for dormancy:

http://howtobrew.com/book/section-1/fermentation/conditioning-processes
 

Gnomebrewer

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Yeast can clean up some fermentation by-products.
This is from From 'Yeast: the Practical Guide to Beer Fermentation' (by Chris White and Jamil Zainasheff), which is well worth purchasing and reading.


Beer matures in the stationary phase, also known as the conditioning phase. Yeast reabsorb much of the diacetyl and acetaldehyde produced during fermentation......
........One of the things you do not want to do is force the yeast into dormancy before they have had every opportunity to clean up after themselves.......
........Our recommendation, especially for homebrewers, is to wait for the yeast to finish their tasks and clean up fermentation by-products as much as possible.

What you can do to speed this up, is improve and control fermentation conditions as much as possible. If you aren't getting many unwanted by-products produced in your beer, there isn't much for the yeast to clean up, so you can package earlier. If you properly control pitch rate and vitality, oxygenation and ferment temperature the wait for clean up is very short!
 

RPh_Guy

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Yeast can clean up some fermentation by-products.
This is from From 'Yeast: the Practical Guide to Beer Fermentation' (by Chris White and Jamil Zainasheff), which is well worth purchasing and reading.


Beer matures in the stationary phase, also known as the conditioning phase. Yeast reabsorb much of the diacetyl and acetaldehyde produced during fermentation......
........One of the things you do not want to do is force the yeast into dormancy before they have had every opportunity to clean up after themselves.......
........Our recommendation, especially for homebrewers, is to wait for the yeast to finish their tasks and clean up fermentation by-products as much as possible.

What you can do to speed this up, is improve and control fermentation conditions as much as possible. If you aren't getting many unwanted by-products produced in your beer, there isn't much for the yeast to clean up, so you can package earlier. If you properly control pitch rate and vitality, oxygenation and ferment temperature the wait for clean up is very short!
+1 all of this.

Yeast clean up acetaldehyde, diacetyl, and other vicinal diketones (VDKs) after & during fermentation.

If you conduct a healthy fermentation (and a diacetyl rest for lagers), the yeast typically finish removing those compounds by the time fermentation is complete, or within a day or two afterwards.
If your fermentation is unhealthy, it may take additional time... Hence the mixed reports.

If you bottle, there's no reason to wait because the yeast in the bottle can clean up.

Cheers
 

Day-Day

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I agree with above, there shouldn't be to much off/undesirable flavors from a strong healthy fermentation. Early in my brewing career I would leave beers in primary for 3-4 weeks before bottling, and often they would still need a few more weeks or longer to really taste good. After learning how to provide a strong healthy fermentation I generally keg my beers two weeks after brew day and that includes dry hopping time, they taste great as soon as they are carbed. My IPA's usually taste good when taking a gravity reading after only 7-10 days in primary and are usually at terminal gravity... but I just let them go two weeks before kegging. Some styles absolutely benefit from aging (big stouts, etc.) but that's a different story than aging out off flavors.
 

RPh_Guy

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Some styles absolutely benefit from aging (big stouts, etc.) but that's a different story than aging out off flavors.
Is it?
Higher OG just means they yeast have a more difficult task, but with the right help the beer or wine can still be immediately drinkable and delicious.

Personally I've made a couple 9% beers and some 10-15% wines & meads that were great and don't need aging.
For example my faux ice cider at 1.140 OG was delicious throughout the [slow] fermentation.
 

Qhrumphf

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But as said above, if fermentation management is good (proper healthy pitch, sufficient O2, adequate yeast nutrition, proper temp control, etc), beer shouldn't need more than a day or two after FG to be completely ready (and if spunding or racking to cask, that includes to drink).
 

Day-Day

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Is it?
Higher OG just means they yeast have a more difficult task, but with the right help the beer or wine can still be immediately drinkable and delicious.

Personally I've made a couple 9% beers and some 10-15% wines & meads that were great and don't need aging.
For example my faux ice cider at 1.140 OG was delicious throughout the [slow] fermentation.
I'm talking serious off flavors, unwanted esters, excessive fusel alcohols, things of that nature. I agree many beers even large ones may not need aging, especially if there were never any off flavors to begin with. I like my stouts aged (for the most part), I find that those bigger darker beers become more complex, richer, and more balanced for me when aged... but that's my taste... others may disagree but it's completely subjective.

My point with my original statement is there is a difference of yeast cleaning up undesirable traits in a beer that occurred because of poor fermentation vs aging (or not aging) a well made beer to your desired taste (in my case aging a stout)... in your case drinking your well made faux cider immediately...

I've had to age out some things... I had one stout that was pretty much undrinkable until 8 months in the bottle... but it was one of the best beers I've ever brewed or had.. and I'm talking about aging out because of poor fermentation, this was early in my brewing career.
 

Bobby_M

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In my experience, it doesnt take long if you are able to prevent a post ferment cool down. During active fermentation heat is being produced. As activity ramps down, the beer cools and forces more slow down etc. I bump my controller up a few degrees when fermentation slows to keep activity high and leave it there for 3 days past FG.
 

masskrug

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Not so sure if the yeast are finishing the job or things are just settling to the bottom. The yeast is done in a week or so, but everything needs time to settle and compact at the bottom of the fermentor.
 
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