Author Topic: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!  (Read 12854 times)

Offline brulosopher

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #15 on: October 19, 2015, 01:05:29 pm »
I honestly can't tell a difference using a mix stir over when I used to use O2, even on big beers - or I'd have switched back. Aerating thoroughly and using plenty of healthy yeast get's what I'm after.
I'm with you, I've never actually used O2 but my beers are at least as good those from dudes I know who do use it.
The aroma was perceivable by the biased brewer.

While the gravity difference is measurable - this is the second triangle that didn't show a statistical +/- over the drier beer. This boggles me.

Let's be careful about jumping to conclusions.

I am now really curious about this in a more delicate lager beer. Everything I read points to both vitality and biomass/weight needed for consistently well attenuated lagers - and O2 is discussed in depth in Boulton and Quain, as well as White's Yeast book.
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Blah blah, small sample size, yadda yadda, rigorous definition of significance, see my other comments. ;)

Seriously, though, be careful about reading too much into the results of a single trial when one taster could flip the test for significance.
I agree with Sean. That said, combining these and similar results with my anecdotal evidence, I'm pretty convinced pure O2 isn't a necessity on the homebrew scale... even for big beers.

I'd never give this advice though, as I've no desire to be tarred and feathered.
It's all fine and dandy until you bring lagers into the equation.
I'm not sure it'll matter, but you better believe we'll test it out.

Offline erockrph

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #16 on: October 19, 2015, 01:07:44 pm »
It's all fine and dandy until you bring lagers into the equation.
I'm not sure it'll matter, but you better believe we'll test it out.
I agree, Marshall. I think if you have an adequate, healthy pitch of yeast, then it doesn't matter if you're brewing a lager or an ale.
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Offline brulosopher

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Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #17 on: October 19, 2015, 01:09:19 pm »
It's all fine and dandy until you bring lagers into the equation.
I'm not sure it'll matter, but you better believe we'll test it out.
I agree, Marshall. I think if you have an adequate, healthy pitch of yeast, then it doesn't matter if you're brewing a lager or an ale.

I'm staring to think vitality starters may be the log lost brewing secret, whether lager or ale, low or high OG. Got a lot more testing to do, but so far, I'm beyond impressed.

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #18 on: October 19, 2015, 02:11:21 pm »
So both starters were well oxygenated, allowing yeast to manufacture all the fatty acids and ergosterol needed to build numbers up. The main difference was that the yeast pitched into the aerated wort could make even more. Maybe if a starter is well aerated, there's no need to also aerate the wort.

However, a stir plate without supplemental aeration does not provide as much aeration as home brewers have been led to believe.   Plus, the turbulence encountered in stirred cultures results in the cells being stressed; therefore, the stir plate is not the true reason for the outcome.

The more accurate reason behind for the results in this test lie in the chosen strain's O2 demands.  WLP007 is Whitbread B.   Whitbread B is a class O2 yeast culture with respect to O2 demands, which means that it is a relative lightweight when it comes to placing dissolved O2 demands on a medium.  A class O2 yeast strain's dissolved O2 demands can be met by dissolved O2 in the greater than 4ppm and less than or equal to 8ppm range.  If this experiment were to be run with WLP037 in a closed fermentation vessel, the results would be more definitive.

For those who are wondering about O2 demand classes, Brian Kirsop wrote the seminal paper on the topic: http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1974.tb03614.x/epdf

By the way, in addition to being known as Wyeast 1098, White Labs WLP007, and Fermentis S-04,  Whitbread B is also known as NCYC 1026.

NCYC 1026

Information
   Flocculent.
NewFlo type flocculation.
       1:5:4:5:5
       O2, DMS 33 µg/l, low acetic, high lactic (which is why the strain produces slightly tart beers),
       diacetyl 0.42ppm only, used commercially in Tower Fermenters (continuous process),
       non head-forming, no estery flavour. Contains 2µ plasmid.
Depositor
   British Brewery
Deposit Name
   Saccharomyces cerevisiae
Month of deposit
   June
Deposit Year
   1958
Habitat
   Ale production strain.

« Last Edit: October 20, 2015, 07:22:33 am by S. cerevisiae »

Offline charles1968

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #19 on: October 19, 2015, 02:46:07 pm »
So both starters were well oxygenated, allowing yeast to manufacture all the fatty acids and ergosterol needed to build numbers up. The main difference was that the yeast pitched into the aerated wort could make even more. Maybe if a starter is well aerated, there's no need to also aerate the wort.

However, a stir plate without supplemental aeration does not provide as much aeration as home brewers have been led to believe.   Plus, the turbulence encountered in stirred cultures results in the cells being stressed; therefore, the stir plate is not the true reason for the outcome.

The more accurate reason behind for the results in this test lie in the chosen strain's O2 demands.  WLP007 is Whitbread B.   Whitbread B is a class O2 yeast culture with respect to O2 demands, which means that it is relative lightweight when it comes to placing dissolved O2 demands on a medium.  A class O2 yeast strain's dissolved O2 demands can be met by dissolved O2 in the greater than 4ppm and less than or equal to 8ppm range.  If this experiment were to be run with WLP037 in a closed fermentation vessel, the results would be more definitive.

For those who are wondering about O2 demand classes, Brian Kirsop wrote the seminal paper on the topic: http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.1974.tb03614.x/epdf

By the way, in addition to being known as Wyeast 1098, White Labs WLP007, and Fermentis S-04,  Whitbread B is also known as NCYC 1026.

NCYC 1026

Information
   Flocculent.
NewFlo type flocculation.
       1:5:4:5:5
       O2, DMS 33 µg/l, low acetic, high lactic (which is why the strain produces slightly tart beers),
       diacetyl 0.42ppm only, used commercially in Tower Fermenters (continuous process),
       non head-forming, no estery flavour. Contains 2µ plasmid.
Depositor
   British Brewery
Deposit Name
   Saccharomyces cerevisiae
Month of deposit
   June
Deposit Year
   1958
Habitat
   Ale production strain.

Interesting paper. Regarding the stir plate - even if the yeast cells from a stir plate are dead, they'll still contribute ergosterol when pitched and will help make up for an O2 deficit.

Offline a10t2

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #20 on: October 19, 2015, 03:12:07 pm »
While the gravity difference is measurable - this is the second triangle that didn't show a statistical +/- over the drier beer. This boggles me.

That's actually the least surprising part, IME. QA panels can never pick out small differences in FG.
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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #21 on: October 19, 2015, 03:14:13 pm »
It's all fine and dandy until you bring lagers into the equation.
I'm not sure it'll matter, but you better believe we'll test it out.
I agree, Marshall. I think if you have an adequate, healthy pitch of yeast, then it doesn't matter if you're brewing a lager or an ale.

And that makes perfect sense if you think about the role of oxygen.  It's to facilitate cell growth.  If you pitch enough healthy yeast, then you need minimal, f any, cell growth.


waiting for Mark to tell me where I'm wrong....;)
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Offline brulosopher

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #22 on: October 19, 2015, 03:25:24 pm »

It's all fine and dandy until you bring lagers into the equation.
I'm not sure it'll matter, but you better believe we'll test it out.
I agree, Marshall. I think if you have an adequate, healthy pitch of yeast, then it doesn't matter if you're brewing a lager or an ale.

And that makes perfect sense if you think about the role of oxygen.  It's to facilitate cell growth.  If you pitch enough healthy yeast, then you need minimal, f any, cell growth.


waiting for Mark to tell me where I'm wrong....;)

I'm waiting Mark to confirm that 007 is not the same as S-04... I used to think so, then I was told it's not... now I'm not sure.

Offline narcout

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #23 on: October 19, 2015, 04:24:50 pm »
And that makes perfect sense if you think about the role of oxygen.  It's to facilitate cell growth.  If you pitch enough healthy yeast, then you need minimal, f any, cell growth.

I think the idea is if you pitch yeast with sufficient UFA and ergosterol reserves, they already have what they need for healthy replication and do not need to synthesize further sterols or UFA, which would require access to oxygen.

The healthy pitched yeast is still replicating, it just doesn't need much dissolved O2 to do so.   

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Offline Steve Ruch

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #24 on: October 19, 2015, 04:42:03 pm »
Some people think that you don't need to add any oxygen at all if using dry yeast.
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Offline Stevie

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #25 on: October 19, 2015, 05:13:46 pm »
I've heard one could oxygenate with olive oil.





;)

Offline klickitat jim

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #26 on: October 19, 2015, 05:16:19 pm »
I've heard one could oxygenate with olive oil.





;)
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Offline neddles

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #27 on: October 19, 2015, 10:12:03 pm »

It's all fine and dandy until you bring lagers into the equation.
I'm not sure it'll matter, but you better believe we'll test it out.
I agree, Marshall. I think if you have an adequate, healthy pitch of yeast, then it doesn't matter if you're brewing a lager or an ale.

And that makes perfect sense if you think about the role of oxygen.  It's to facilitate cell growth.  If you pitch enough healthy yeast, then you need minimal, f any, cell growth.


waiting for Mark to tell me where I'm wrong....;)

I'm waiting Mark to confirm that 007 is not the same as S-04... I used to think so, then I was told it's not... now I'm not sure.
Yeah, I always thought S-04 was WY1099. Don't remember where I learned that but maybe it was wrong.

S. cerevisiae

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #28 on: October 20, 2015, 07:57:40 am »
Interesting paper. Regarding the stir plate - even if the yeast cells from a stir plate are dead, they'll still contribute ergosterol when pitched and will help make up for an O2 deficit.

The practice of a spinning a culture until it sediments results in low ergosterol and UFA reserves, which is why sedimented cells take longer to exit the lag phase and place higher O2 demands on the wort.  The yeast from a White Labs vial will consume enough of the available carbon in a 1L starter that carbon will start to become limiting within 18 hours, resulting in the normal transition to quiescence.  By twenty-four hours, only the cells from low viability White Labs cultures have not started to undergo the survival-related morphological changes that occur when carbon becomes limiting.   

A stir plate does not aerate a culture.  About all it does is keep the medium homogeneous and degas the culture. O2 pickup is bounded by the amount of surface area between the gas and the liquid based on Henry's Law, which is why proper culturing glassware is short and wide (e.g., a Fernbach flask versus an Erlenmeyer Flask).  Little to no O2 enters the fermentation after the culture starts to outgas because the culture is under positive pressure.  Brewing strains do not reproduce aerobically in wort above approximately 1.008 due to being Crabtree positive.

Ergosterol production requires O2, and the ergosterol the is synthesized while O2 is still in solution is shared between mother cells and daughter cells. Ergosterol is used throughout fermentation to maintain cell membranes.  Ergosterol is to yeast cells what cholesterol is to human cells.  It is a precursor to vitamin D2.
« Last Edit: October 22, 2015, 07:24:21 am by S. cerevisiae »

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Re: Wort Aeration - Pt. 3: Nothing vs. Pure Oxygen | exBEERiment Results!
« Reply #29 on: October 20, 2015, 08:32:46 am »
Some people think that you don't need to add any oxygen at all if using dry yeast.

That is correct.  Dry yeast does not require O2 on the initial pitch due to the fact that it is propagated in a bioreactor below the Crabtree threshold, which results in aerobic growth versus anaerobic growth.  Since ergosterol and UFAs are synthesized in the aerobic metabolic pathway and O2 never becomes limiting, the yeast cells have fully charged ergosterol and UFA reserves. 

With that said, O2 is not the key to forcing aerobic growth.  O2 and holding the amount of available glucose in a steady state below the Crabtree threshold is the key to forcing aerobic growth with brewing yeast because Saccharomyces is Crabtree positive.  Aerobic propagation is significantly more efficient than anaerobic propagation. A yeast cell derives 18 times more energy by metabolizing glucose via the aerobic metabolic pathway than it does via the anaerobic metabolic pathway (36 ATP versus 2 ATP), which is why the big boys use aerobic propagation.  Aerobic propagation requires a yeast propagator to be able to maintain a chemically static environment on a large scale.  If you look up Fermentis' parent company Lesaffre, you will discover that they are leaders in the design of bioreactors.  Bioreactor design is a specialty within the field of biochemical engineering.