Author Topic: racking to limit attenuation  (Read 2151 times)

Offline pinnah

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racking to limit attenuation
« on: March 09, 2013, 01:14:00 PM »
Wondering if there are any issues to be aware of
when racking prior to reaching potential terminal gravity?

I have a honey lager that I would like to stop before it drops any lower.
I am at 80% atten. right now, but it has only been fermenting two weeks and is active.

Planning on racking to secondary vessel and cold crashing.

Thanks for any thoughts.

Offline HydraulicSammich

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Re: racking to limit attenuation
« Reply #1 on: March 09, 2013, 01:25:57 PM »
It may be finished with fermentation!  What has been the gravity over the last 2 or three days.  Is it stable?  I am betting it is finished.  However, I would let it sit another two weeks just to clean up after itself then rack and lager.  I don't risk the sulfur taste.
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Offline denny

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Re: racking to limit attenuation
« Reply #2 on: March 09, 2013, 01:40:23 PM »
Just racking will not necessarily stop fermentation.  Neither will refrigeration.  You need to kill off the yeast somehow.
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Offline gmac

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Re: racking to limit attenuation
« Reply #3 on: March 09, 2013, 05:37:49 PM »
You need to kill off the yeast somehow.

Plutonium?

Offline pinnah

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Re: racking to limit attenuation
« Reply #4 on: March 10, 2013, 08:22:10 AM »
It may be finished with fermentation!  What has been the gravity over the last 2 or three days.  Is it stable?  I am betting it is finished.  However, I would let it sit another two weeks just to clean up after itself then rack and lager.  I don't risk the sulfur taste.

You are probably right, it is pretty much finished. Maybe 95% done?
What is the sulfur taste you mention?  A result of not letting the yeasties clean up?

Just racking will not necessarily stop fermentation.  Neither will refrigeration.  You need to kill off the yeast somehow.

Wow.  I thought if you racked off the primary cake and cold crashed it you basically halt the fermentation and the yeast drop out?  Maybe a few months of lagering would do the trick?

Offline denny

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Re: racking to limit attenuation
« Reply #5 on: March 10, 2013, 09:47:31 AM »
You need to kill off the yeast somehow.

Plutonium?

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Offline philljennbrewing

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Re: racking to limit attenuation
« Reply #6 on: March 10, 2013, 10:10:11 AM »
You can use Potassium Sorbate (used when sweetening wines and meads). Kills off all yeast to prevent renewed fermentation. Available in your local brew shop, wine additive section.

Online Thirsty_Monk

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Re: racking to limit attenuation
« Reply #7 on: March 11, 2013, 07:06:41 AM »
Just racking will not necessarily stop fermentation.  Neither will refrigeration.  You need to kill off the yeast somehow.
The easeast way to do this is to filter the yeast out.
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Offline mmitchem

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Re: racking to limit attenuation
« Reply #8 on: March 11, 2013, 07:09:37 AM »
You need to kill off the yeast somehow.

Plutonium?

Glow in the dark beer!

Could this beer fuel the flux capacitor and help to achieve 1.21 gigawatts???
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Offline kylekohlmorgen

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Re: racking to limit attenuation
« Reply #9 on: March 11, 2013, 07:25:20 AM »
I tend to do everything I can to make sure the yeast complete the full cycle of fermentation. If you halt yeast activity early, whether on purpose or by accident, you risk fermentation off-flavors such as butter (diacetyl) or astringent green apple (acetylaldehyde). This is especially true in a lager fermentation.

I'd rather have a beer that is clean but too dry than one that has the proper finishing gravity but is flawed by one of the above flavors.

If you are kegging: After fermentation is complete and the yeast have cleaned up their by-products, you can add potassium sorbate to kill the yeast and then back-sweeten with more honey. Adding honey after fermentation is a great way to get honey flavor and aroma (kind of like dry-hopping with honey, while adding gravity/sugars).

If you're bottling: at bottling, add maltodextrin along with your priming sugar and bottling yeast. Figure out the amount of MD powder needed to add the desired gravity points to your bottling volume. Dissolve the powder with your priming sugar.
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Offline tschmidlin

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Re: racking to limit attenuation
« Reply #10 on: March 11, 2013, 10:03:55 PM »
Quick point - sorbate does not kill yeast, it prevents it from starting fermentation again.  And it is not necessarily 100% effective.  You can definitely use it, but just be aware of the possibility of renewed fermentation if you aren't careful.  I would keep it cold to minimize the risk of problems.
Tom Schmidlin

Offline pinnah

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Re: racking to limit attenuation
« Reply #11 on: March 12, 2013, 04:29:28 AM »
Hey thanks all for the recommendations!

Especially this thoughtful explanation:
I tend to do everything I can to make sure the yeast complete the full cycle of fermentation. If you halt yeast activity early, whether on purpose or by accident, you risk fermentation off-flavors such as butter (diacetyl) or astringent green apple (acetylaldehyde). This is especially true in a lager fermentation.

I'd rather have a beer that is clean but too dry than one that has the proper finishing gravity but is flawed by one of the above flavors.

Wish I had read it before I acted.  That will teach me to ask questions on the weekend. :-X




I went ahead and transferred to secondary glass and set it outside on the porch for the night.
23 degrees will drop some yeasties.

Not too worried about stopping fermentation at this point,
airlock activity has all but ceased, but hoping I have caused no off flavors.

I guess I do not fully understand the yeast "clean up after themselves" thing.
There is a gorgeous white yeast cake at the bottom of that secondary vessel now.
Are those yeasties somehow incapable of cleaning up their mess?
Whatcha got?



Offline mmitchem

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Re: racking to limit attenuation
« Reply #12 on: March 12, 2013, 05:38:23 AM »
The yeast will clean up, or take back up, things like diacetyl at the end of fermentation. The thing is...to do so, the yeast have to be active and in suspension. Since you cold crashed your secondary and sent your yeast to the bottom (dormant), they will not have the chance to do so.

As said previously, it is better to let the fermentation do its thing fully, go as low as it wants to. You can always adjust your recipe in the future to limit the amount of fermentable sugars, body, etc. Letting that yeast go all the way to the end before cold crashing has several benefits that go far beyond just the ABV.
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Offline tschmidlin

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Re: racking to limit attenuation
« Reply #13 on: March 12, 2013, 09:26:00 AM »
The yeast will clean up, or take back up, things like diacetyl at the end of fermentation. The thing is...to do so, the yeast have to be active and in suspension. Since you cold crashed your secondary and sent your yeast to the bottom (dormant), they will not have the chance to do so.
I am not convinced that this is 100% the case - I believe it will slow, but not stop the process.  I think it comes down to surface area and availability.  By cold crashing you massively reduce the surface area of yeast exposed to the beer.  You also drastically reduce that yeasts' exposure to compounds that need to get cleared up.  During an active or semi active fermentation the CO2 bubbling out is constantly mixing the beer, so the non-flocculating yeast and the compounds like diacetyl are being mixed throughout.  When the beer has been chilled and CO2 is no longer coming out, the compounds have to diffuse through the beer to come into contact with the yeast, which is now mostly at the bottom.  So I think it is these two factors, combined with the lower yeast activity due to the cold, that keep the yeast from cleaning up the beer.  And I don't mean to minimize the decreased activity due to the lower temperature, but it is not zero.
Tom Schmidlin

Offline kylekohlmorgen

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Re: racking to limit attenuation
« Reply #14 on: March 12, 2013, 09:50:01 AM »
The yeast will clean up, or take back up, things like diacetyl at the end of fermentation. The thing is...to do so, the yeast have to be active and in suspension. Since you cold crashed your secondary and sent your yeast to the bottom (dormant), they will not have the chance to do so.
I am not convinced that this is 100% the case - I believe it will slow, but not stop the process.  I think it comes down to surface area and availability.  By cold crashing you massively reduce the surface area of yeast exposed to the beer.  You also drastically reduce that yeasts' exposure to compounds that need to get cleared up.  During an active or semi active fermentation the CO2 bubbling out is constantly mixing the beer, so the non-flocculating yeast and the compounds like diacetyl are being mixed throughout.  When the beer has been chilled and CO2 is no longer coming out, the compounds have to diffuse through the beer to come into contact with the yeast, which is now mostly at the bottom.  So I think it is these two factors, combined with the lower yeast activity due to the cold, that keep the yeast from cleaning up the beer.  And I don't mean to minimize the decreased activity due to the lower temperature, but it is not zero.

Makes a lot of sense.

Tom - do you think this is why you don't need a diacetyl rest with more powdery yeasts like WLP001/1056? Or is it that some yeasts are just better at completing fermentation in less-than-ideal conditions?
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