Poll

Which is the most practical & effective way to aerate Wort or equivalent?

Agitation - Shake Carboy
9 (23.7%)
Injection - Air Stone with pure O2
19 (50%)
Injection - Air Stone with pure room air
2 (5.3%)
Splashing - Pour through sanitized wire mess strainer or equivalent
3 (7.9%)
Olive Oil - Pin drop per 5 gallons
1 (2.6%)
Packet Yeast - No Aeration Needed, Yeast Already Sterol Rich
1 (2.6%)
I never worry about it - works out fine
3 (7.9%)

Total Members Voted: 38

Author Topic: Best Way to Aerate Wort  (Read 6060 times)

Offline denny

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Re: Best Way to Aerate Wort
« Reply #15 on: September 13, 2016, 03:32:46 PM »
Isn't aeration not all that necessary if you pitch enough healthy yeast?

Indeed.
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Offline Lazy Ant Brewing

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Re: Best Way to Aerate Wort
« Reply #16 on: September 13, 2016, 06:31:25 PM »
Is it correct that dry yeast needs no aeration at all?

Thanks in advance for your replies.
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Offline Stevie

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Re: Best Way to Aerate Wort
« Reply #17 on: September 13, 2016, 06:43:25 PM »
Is it correct that dry yeast needs no aeration at all?

Thanks in advance for your replies.
That's what some say. Basically they have everything they need to get started in the dry form. Liquid yeast relies on oxygen to synthesize sterols, or some sciencey answer.

Offline denny

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Re: Best Way to Aerate Wort
« Reply #18 on: September 13, 2016, 07:01:32 PM »
Is it correct that dry yeast needs no aeration at all?

Thanks in advance for your replies.

Yes, because the cell count of dry yeast is so high, most of the time there is no need for cell growth and therefore no need for aeration. 
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Offline neddles

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Re: Best Way to Aerate Wort
« Reply #19 on: September 13, 2016, 09:00:16 PM »
If pitching the "proper" amount of yeast there is no need for growth and therefor no need for any dissolved O2 in the wort…. should I be expecting to find the same number of cells at the bottom of my fermentor after fermentation that I pitched before fermentation? Or what am I missing here?

Offline denny

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Re: Best Way to Aerate Wort
« Reply #20 on: September 14, 2016, 01:06:40 AM »
If pitching the "proper" amount of yeast there is no need for growth and therefor no need for any dissolved O2 in the wort…. should I be expecting to find the same number of cells at the bottom of my fermentor after fermentation that I pitched before fermentation? Or what am I missing here?

Hmmm...good question.  I don't really know.  All I can say is that I successfully repitch yeast from a fermentation done like that.
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Offline neddles

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Re: Best Way to Aerate Wort
« Reply #21 on: September 14, 2016, 02:53:43 AM »
If pitching the "proper" amount of yeast there is no need for growth and therefor no need for any dissolved O2 in the wort…. should I be expecting to find the same number of cells at the bottom of my fermentor after fermentation that I pitched before fermentation? Or what am I missing here?

Hmmm...good question.  I don't really know.  All I can say is that I successfully repitch yeast from a fermentation done like that.

And your experience doing that is most valuable and applicable. But the idea that I will get zero increase in the number of yeast cells I pitched from a ferment of 5.5 gallons is pretty hard to believe.

Offline stevecrawshaw

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Re: Best Way to Aerate Wort
« Reply #22 on: September 14, 2016, 01:19:12 PM »
My method's not on that list, so FWIW, this is it.

I ferment in a plastic jerrycan from no-chill and have around 15L wort in a 23L jerrycan, so headspace. When it's cool I squirt pure O2 into the headspace after pitching and shake like it owes me money. After 18 - 24 hours fermentation I do the same again following the guidance in "Yeast" which is that this is the period at which oxygen is most beneficial for the synthesis of sterols. This practice also aligns with the principles of the shaken not stirred starter in that the availability of oxygen to wort is maximised in the oxygen rich foam from shaking.

As others have said, this may not be necessary, but my fermentations are always healthy and never any off flavours from fermenting.
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Offline narcout

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Re: Best Way to Aerate Wort
« Reply #23 on: September 14, 2016, 08:19:30 PM »
Is it correct that dry yeast needs no aeration at all?

Thanks in advance for your replies.

http://www.lallemandyeast.com/articles/crabtree-effect-and-overflow-metabolism

"When the wort has more than >0.2% sugar, the function of the O2 is to assist the yeast in producing lipids. The lipids in the cell wall act as a growth factor by keeping the cell wall fluid, allowing buds to form. The production of these lipids require trace amounts of oxygen to move the squalene to the lipid stage. With out O2 the mother cell cannot produce any lipids and must shares her lipids with her daughter cell. This can occur for about 3 - 4 cycles before the cell wall becomes leathery and will not allow a new bud to form. Active Dry Beer Yeast initially contain enough lipids in their cell wall for 3 - 4 growth cycles. This is enough to complete most beer fermentations."
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Offline Joe Sr.

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Re: Best Way to Aerate Wort
« Reply #24 on: September 14, 2016, 08:33:04 PM »
If pitching the "proper" amount of yeast there is no need for growth and therefor no need for any dissolved O2 in the wort…. should I be expecting to find the same number of cells at the bottom of my fermentor after fermentation that I pitched before fermentation? Or what am I missing here?

Hmmm...good question.  I don't really know.  All I can say is that I successfully repitch yeast from a fermentation done like that.

And your experience doing that is most valuable and applicable. But the idea that I will get zero increase in the number of yeast cells I pitched from a ferment of 5.5 gallons is pretty hard to believe.

If there's enough cells in a dry yeast pack such that there is no cell growth, you could never have an overpitch by re-using a yeast cake, right?  Because the yeast cake would be the same number of cells as a dry yeast pack.  Maybe I'm confused.  I don't think it's possible that there's no growth.
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Offline narcout

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Re: Best Way to Aerate Wort
« Reply #25 on: September 15, 2016, 05:48:21 PM »
If there's enough cells in a dry yeast pack such that there is no cell growth, you could never have an overpitch by re-using a yeast cake, right?

If you pitch a single packet of dry yeast into 5 gallons of wort, there will be several replication periods.

If you assume maximum cell density of 200 billion cells per liter, a 5 gallon batch size, and that a dry yeast packet contains 200 billion cells (I don't know how many cells a dry yeast packet actually contains), you are looking at approximately 4.2 replication periods.  If you assume there are 400 billion cells in a packet, you are looking at approximately 3.2 replication periods.

S.C. laid out the math here:  https://www.experimentalbrew.com/blogs/saccharomyces/yeast-cultures-are-nuclear-weapons

I suppose you could pitch enough yeast so that there was little or no cell growth, but I believe it would negatively impact flavor (that would be an interesting experiment).
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Offline Joe Sr.

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Re: Best Way to Aerate Wort
« Reply #26 on: September 15, 2016, 06:46:07 PM »
If you pitch a single packet of dry yeast into 5 gallons of wort, there will be several replication periods.

because the cell count of dry yeast is so high, most of the time there is no need for cell growth and therefore no need for aeration. 

Assuming growth=replication, Denny's statement seems incorrect.  Hence my extrapolation that if this is correct, you couldn't overpitch using a yeast cake.  Except that I'm certain that using a full yeast cake results in a drastic overpitch.

My understanding is that dry yeast doesn't need oxygen because it has sterol reserves already built up in whatever science-y way they go about making it.
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Offline neddles

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Re: Best Way to Aerate Wort
« Reply #27 on: September 15, 2016, 09:46:16 PM »
If you pitch a single packet of dry yeast into 5 gallons of wort, there will be several replication periods.

because the cell count of dry yeast is so high, most of the time there is no need for cell growth and therefore no need for aeration. 

Assuming growth=replication, Denny's statement seems incorrect.  Hence my extrapolation that if this is correct, you couldn't overpitch using a yeast cake.  Except that I'm certain that using a full yeast cake results in a drastic overpitch.

My understanding is that dry yeast doesn't need oxygen because it has sterol reserves already built up in whatever science-y way they go about making it.
Agree, and Denny has been saying the same thing WRT liquid yeast…paraphrasing, 'if you pitch enough healthy yeast then there will be no growth and therefor no need for dissolved O2 in the wort'.
« Last Edit: September 15, 2016, 09:48:14 PM by neddles »

Offline denny

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Re: Best Way to Aerate Wort
« Reply #28 on: September 15, 2016, 10:21:30 PM »
Agree, and Denny has been saying the same thing WRT liquid yeast…paraphrasing, 'if you pitch enough healthy yeast then there will be no growth and therefor no need for dissolved O2 in the wort'.

I think it's inevitable that there will be some growth, but the need for growth is greatly reduced.
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Offline brewinhard

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Re: Best Way to Aerate Wort
« Reply #29 on: September 15, 2016, 11:16:55 PM »
Keep in mind the viability of the age of the packet you are getting.  Even with how slowly dry yeast drop-off, I can't imagine that 100% of the cells are ready to rock especially when the packet has a bit of age on it. Not all survive the rehydration stage either (whether its in wort or water).