SMB AT Kegging

Filtering, fining, bottling, etc

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wobdee
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SMB AT Kegging

Postby wobdee » Tue May 03, 2016 2:36 pm

Was thinking about this lately. Say you transfer from your fermenter when beer is finished to keg with a 6-10mg/l dose of smb. The smb should help some by scrubbing O2 but doesn't it also kill any yeast that was transfered over as well? Could that dead yeast lead to off flavors?

Also was thinking of other options besides timing the fermentation for Spunding. What about transferring after complete fermentation and adding gyle or speise, anyone try that? I could see where life could get in the way at times you need to transfer.
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Ancient Abbey
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Re: SMB AT Kegging

Postby Ancient Abbey » Tue May 03, 2016 3:08 pm

My bottle says to use at 2 oz per 1/2 gal to sanitize, so I'm not too worried about 6-10 mg/l.

Krausen would work fine. I just did it with my dopplebock as some insurance to ensure I reach EVG.
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Re: SMB AT Kegging

Postby Kit_B » Tue May 03, 2016 3:12 pm

I was always under the impression that it did not kill the yeast, but it removed the oxygen that they need & force them into dormancy.
But...I could be wrong.
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Re: SMB AT Kegging

Postby wobdee » Tue May 03, 2016 3:37 pm

I heard they use it the day before they pitch the yeast for wine to Degas and kill off any wild yeast? After a day it's safe for yeast. I don't know how high a dose it would take to do any damage?
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Re: SMB AT Kegging

Postby wobdee » Wed May 04, 2016 11:41 am

Kit_B wrote:I was always under the impression that it did not kill the yeast, but it removed the oxygen that they need & force them into dormancy.
But...I could be wrong.


Ya, I think your right the more I read into it. It will kill other beasties by eliminating O2 but basically put yeast to sleep temporarily. Shouldn't be a problem.
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Re: SMB AT Kegging

Postby mchrispen » Wed May 04, 2016 2:38 pm

I use K-meta in mead and wine. Exactly as Kit says... the K-meta occludes oxygen, also has a direct effect on LAB in a low pH environment. Sorbates are used as well to prevent cell replication. The dosage is pretty small and should consider the must pH when stabilizing. My GoogleFu failed me or I would put a link.
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Ancient Abbey
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Re: SMB AT Kegging

Postby Ancient Abbey » Sat May 07, 2016 7:36 am

It does't quite make sense to me how eliminating oxygen would kill organisms capable of fermentation. I think either the sulfur dioxide or sulfite are directly toxic to the cells. This suggests that yeast can build a tolerance to sulfur dioxide. Some also suggest to combine with citric acid to sanitize, as the sulfur dioxide is more effective with lower pH.

http://www.danstaryeast.com/articles/su ... wing-yeast
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Re: SMB AT Kegging

Postby mchrispen » Sat May 07, 2016 4:19 pm

The low oxygen is preventing replication as O2 is exhausted much more quickly, stopping any budding, not killing. Toxicity from the sulfur dioxide, etc. requires fairly high doses. I personally do not like using it - even with fresh fruit, especially apples. Anything delicate will carry over some of the sulfur properties. I prefer to only use K-meta + sorbate to stabilize a wine/mead where I want it - and use the pH to calculate the minimum effective dosage. Stabilization doesn't kill, so much as functionally neuter yeast and LAB. The K-meta_sorbate dosage should account for previously added K-meta doses from earlier racking. That is usually near the LODO dosage rates (FYI). I have tried ascorbic acid and I do not like the residual flavors, but I could do more experimentation to see how effective it might be. I have switched recently to 0.45u filtering for a more sterile result, combined with bringing pH levels below 3.2 (again mead and wine).

Perhaps an additional small dosage might be anti-oxidant, but I wonder about the additional sulfur compounds that would remain. They certainly show in a delicate show mead, and I suspect in a helles maybe detectable. It's a different aroma than yeast driven sulfur, IMO.

I think there is a paper on this from UC Davis, I just cannot find it. I will ping Schramm and Moteulo to see if they can point me to the pertinent info.
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SMB AT Kegging

Postby Ancient Abbey » Sat May 07, 2016 8:47 pm

mchrispen wrote:The low oxygen is preventing replication as O2 is exhausted much more quickly, stopping any budding, not killing.


I don't know that much about the specific nutrient requirements of wild yeasts, but S. cerevisiae can bud during fermentation. Oxygen is not required in the form of free dissolved oxygen to do so. The first generation of new cells are formed under aerobic conditions during the first 3-4 hours after aerating. After that, there is no more oxygen in the wort, yet log phase growth lasts for 2-6 days and cell counts do not stop increasing until the population has reached maximum density.

It appears the mechanism of action for sulfites is targeting a broad class of cellular constituents, often enzyme inhibition.

Sulfite MOA.png
Sulfite MOA.png (176.61 KiB) Viewed 638 times


https://books.google.com/books?id=RE_lB ... te&f=false
Last edited by Ancient Abbey on Sun May 08, 2016 7:49 am, edited 2 times in total.
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Re: SMB AT Kegging

Postby narcout » Sun May 08, 2016 12:11 am

Ancient Abbey wrote:I don't know that much about the specific nutrient requirements of wild yeasts, but S. cerevisiae can bud during fermentation. Oxygen is not required in the form of free dissolved oxygen to do so. The first generation of new cells are formed aerobically during the first 3-4 hours after aerating. After that, there is no more oxygen in the wort, yet log phase growth lasts for 2-6 days and cell counts do not stop increasing until the population has reached maximum density.


Isn't all yeast reproduction in wort anaerobic due to the Crabtree effect? I know some older texts say otherwise, but I thought they had been shown to be incorrect.

My understanding is that yeast use oxygen to synthesize UFA and ergosterol which are needed for reproduction. So as long as the yeast has sufficient UFA and ergosterol reserves,they can continue to reproduce without access to additional oxygen. Once those reserves are used up, new buds cannot be formed.

http://www.lallemandyeast.com/articles/ ... metabolism

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