[Bel Air Brewing]

Fortunately there are many yeast varieties available to us as brewers.

But our "go to" house yeast is W-34/70. It can ferment at a wide range of temperatures, all the way down into the mid 30's.

It is perfect for many Euro-Lagers, such as a Munich Helles, German Pils, Oktoberfest.

We have never tried it at traditional ale ferment temps, but I would guess that it would work just fine and produce a great "ale like" beer.

It is easily harvested, and performs great in each subsequent generation.

Perhaps these are the reasons why it is the most widely used yeast strain among the world's brewers.

Back on topic...we do not artificially inject O2 into wort.

[fredthecat]

I think everyone knows mine....😉

lol, i am likely going to give it a try in the next few months in fact.

Back on topic...we do not artificially inject O2 into wort.

please read what i wrote carefully. i really do believe that pure o2 injection is a good idea under certain circumstances. you're using dry yeast and from the beers you mentioned, i assume they have OGs between 1.045 and 1.055 - under these conditions you don't necessarily need pure o2 aeration.

[Saccharomyces]

"Well, we don't and the beer is fine"...

True. And our experience shows empirical data that there is little or no difference in our beers fermented with oxygenated wort versus wort that is simply racked into the fermenter from the boil kettle and then allowed to ferment "as is".

We use mostly liquid yeast, plus harvested yeast.

Again, this is technique only, not a hard and fast procedure that you must follow.

Your data is not representative because you overpitch to the order of three to four times the normal pitch rate.  Oxygen is needed for new cell growth.  One can get away with really flawed technique when one is pitching three to four times the normal pitch rate because it cuts the number of replication periods necessary to reach maximum cell density in half, but does so at the cost of long-term culture health. 

I just read that Pilsner Urquell's pitch rate is 500ml of thick slurry per hectoliter.  That is equivalent to 19ml of thick slurry per gallon.

[Saccharomyces]

Dry yeast normally does not need much in the way of dissolved O₂ because it is propagated aerobically in a medium that is below the Crabtree threshold (S.G. of 1.0008).  Aerobic propagation leads to cells that come out of the process with well, if not fully-charged ergosterol and unsaturated fatty acid reserves. 

That being said, the above does not hold for liquid and repitched yeast because liquid yeast propagation and fermentations occur in a medium above the Crabtree threshold. The number one problem that occurs when brewers who have only used dry yeast switch to liquid yeast is failure to adequately aerate their wort. One can get away with splash aeration with O1, maybe O2 yeast strains, but it is a recipe for under performance with O3 and O4 O₂ yeast strains. Almost all Yorkshire strains are O3 or 04 with respect to O₂ demands.

Class O1 - yeast cultures with O₂ demands that can be satisfied with half-air saturated wort (4ppm)
Class O2 - yeast cultures with O₂ demands that can be satisfied with air saturated wort (8ppm)
Class O3 - yeast cultures with O₂ demands that can be satisfied with pure O₂ wort (20ppm)
Class O4 - yeast cultures with O₂ demands that cannot be satisfied with pure O₂  saturated wort

Fishtails are used for O4 yeast cultures.  The cultures have such high O₂ requirements that they have to be roused and re-aerated mid-fermentation.

From https://www.ncyc.co.uk/saccharomyces-cerevisiae-1333 :

NCYC 1333

Information         Flocculent. O3/O4. Head forming Yorkshire Stone Square type recommended for bottled Pale ale.
Depositor            British Brewery
Deposit Name      Saccharomyces cerevisiae
Month of deposit  January
Deposit Year        1974
Habitat                Ale production strain - Yorkshire Stone Square type recommended for bottled Pale ale.
 

Please notice the strain above is classified as O3/O4 with respect to O₂ demands.


Once again, here is Brian Kirsop's Seminal paper on the subject entitled "Oxygen in Brewery Fermentations": https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1974.tb03614.x


From "The effect of wort aeration on fermentation, maturation and volatile components of beer produced on an industrial scale" (https://onlinelibrary.wiley.com/doi/full/10.1002/jib.392):

"Wort aeration control is difficult. Insufficient aeration can lead to an insufficient revitalization of the yeast, growing deficiency and low fermentation rates. An over‐aeration may lead to high biomass amount 6.

Yeast which are not aerated are able to grow only weakly during fermentation, and the consumption of sugar is also low. The activity of yeast increased with the degree of aeration, reading a maximum level after 5 h of aeration, under the adopted aerating conditions 7."

[fredthecat]

Dry yeast normally does not need much in the way of dissolved O₂ because it is propagated aerobically in a medium that is below the Crabtree threshold (S.G. of 1.0008).  Aerobic propagation leads to cells that come out of the process with well, if not fully-charged ergosterol and unsaturated fatty acid reserves. 

That being said, the above does not hold for liquid and repitched yeast because liquid yeast propagation and fermentations occur in a medium above the Crabtree threshold. The number one problem that occurs when brewers who have only used dry yeast switch to liquid yeast is failure to adequately aerate their wort. One can get away with splash aeration with O1, maybe O2 yeast strains, but it is a recipe for under performance with O3 and O4 O₂ yeast strains. Almost all Yorkshire strains are O3 or 04 with respect to O₂ demands.

Class O1 - yeast cultures with O₂ demands that can be satisfied with half-air saturated wort (4ppm)
Class O2 - yeast cultures with O₂ demands that can be satisfied with air saturated wort (8ppm)
Class O3 - yeast cultures with O₂ demands that can be satisfied with pure O₂ wort (20ppm)
Class O4 - yeast cultures with O₂ demands that cannot be satisfied with pure O₂  saturated wort

Fishtails are used for O4 yeast cultures.  The cultures have such high O₂ requirements that they have to be roused and re-aerated mid-fermentation.

From https://www.ncyc.co.uk/saccharomyces-cerevisiae-1333 :

NCYC 1333

Information         Flocculent. O3/O4. Head forming Yorkshire Stone Square type recommended for bottled Pale ale.
Depositor            British Brewery
Deposit Name      Saccharomyces cerevisiae
Month of deposit  January
Deposit Year        1974
Habitat                Ale production strain - Yorkshire Stone Square type recommended for bottled Pale ale.
 

Please notice the strain above is classified as O3/O4 with respect to O₂ demands.


Once again, here is Brian Kirsop's Seminal paper on the subject entitled "Oxygen in Brewery Fermentations": https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1974.tb03614.x


From "The effect of wort aeration on fermentation, maturation and volatile components of beer produced on an industrial scale" (https://onlinelibrary.wiley.com/doi/full/10.1002/jib.392):

"Wort aeration control is difficult. Insufficient aeration can lead to an insufficient revitalization of the yeast, growing deficiency and low fermentation rates. An over‐aeration may lead to high biomass amount 6.

Yeast which are not aerated are able to grow only weakly during fermentation, and the consumption of sugar is also low. The activity of yeast increased with the degree of aeration, reading a maximum level after 5 h of aeration, under the adopted aerating conditions 7."

i didn't want to beg of you directly, but i was hoping you would answer my questions. that link is an awesome looking site that i was unaware of

do you know of a chart that shows some yeasts and their oxygenation classes? i searched some yeasts on the site, but they are not labelled directly to correspond with known brand-names and product numbers.

I will keep checking this site, and likely compile an excel file if i can make any connections. i see not all strains there have oxygen requirements listed

[Oiscout]

I was waiting patiently too, very clever screen name aswell

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[Richard]

Does a SNS starter provide enough aeration for a yeast that is O3/O4 (for OG of ~1.060), or should the wort be oxygenated in addition?

[denny]

Does a SNS starter provide enough aeration for a yeast that is O3/O4 (for OG of ~1.060), or should the wort be oxygenated in addition?

Are you talking about a starter for dry yeast?

[Richard]

Does a SNS starter provide enough aeration for a yeast that is O3/O4 (for OG of ~1.060), or should the wort be oxygenated in addition?

Are you talking about a starter for dry yeast?

No, I am talking about the Yorkshire category yeasts that were said to be Class O3/O4 in their oxygen requirements. In particular WY1469.

[fredthecat]

Does a SNS starter provide enough aeration for a yeast that is O3/O4 (for OG of ~1.060), or should the wort be oxygenated in addition?

Are you talking about a starter for dry yeast?

No, I am talking about the Yorkshire category yeasts that were said to be Class O3/O4 in their oxygen requirements. In particular WY1469.

i have never used one, but im guessing that if you achieved 10ppm (much less than the recommended oxygenation for 03/04) and just left it to ferment you would probably have it ferment a typical (1.04-1.05) gravity wort pretty successfully. however, would it be an ideal fermentation, or would it work with a higher gravity? im guessing not.

the factors involved with oxygenation seem to be
-strain (including dry vs liquid or repitching)
-OG

if you have a strain that has extreme demands for oxygen but a modest OG, it will probably work to a degree.

for west yorkshire, maybe you could aerate it after 12 hours again? and then another 12 hours in?

[erockrph]

Dry yeast normally does not need much in the way of dissolved O₂ because it is propagated aerobically in a medium that is below the Crabtree threshold (S.G. of 1.0008).  Aerobic propagation leads to cells that come out of the process with well, if not fully-charged ergosterol and unsaturated fatty acid reserves. 

That being said, the above does not hold for liquid and repitched yeast because liquid yeast propagation and fermentations occur in a medium above the Crabtree threshold. The number one problem that occurs when brewers who have only used dry yeast switch to liquid yeast is failure to adequately aerate their wort. One can get away with splash aeration with O1, maybe O2 yeast strains, but it is a recipe for under performance with O3 and O4 O₂ yeast strains. Almost all Yorkshire strains are O3 or 04 with respect to O₂ demands.

Class O1 - yeast cultures with O₂ demands that can be satisfied with half-air saturated wort (4ppm)
Class O2 - yeast cultures with O₂ demands that can be satisfied with air saturated wort (8ppm)
Class O3 - yeast cultures with O₂ demands that can be satisfied with pure O₂ wort (20ppm)
Class O4 - yeast cultures with O₂ demands that cannot be satisfied with pure O₂  saturated wort

Fishtails are used for O4 yeast cultures.  The cultures have such high O₂ requirements that they have to be roused and re-aerated mid-fermentation.

From https://www.ncyc.co.uk/saccharomyces-cerevisiae-1333 :

NCYC 1333

Information         Flocculent. O3/O4. Head forming Yorkshire Stone Square type recommended for bottled Pale ale.
Depositor            British Brewery
Deposit Name      Saccharomyces cerevisiae
Month of deposit  January
Deposit Year        1974
Habitat                Ale production strain - Yorkshire Stone Square type recommended for bottled Pale ale.
 

Please notice the strain above is classified as O3/O4 with respect to O₂ demands.


Once again, here is Brian Kirsop's Seminal paper on the subject entitled "Oxygen in Brewery Fermentations": https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.1974.tb03614.x


From "The effect of wort aeration on fermentation, maturation and volatile components of beer produced on an industrial scale" (https://onlinelibrary.wiley.com/doi/full/10.1002/jib.392):

"Wort aeration control is difficult. Insufficient aeration can lead to an insufficient revitalization of the yeast, growing deficiency and low fermentation rates. An over‐aeration may lead to high biomass amount 6.

Yeast which are not aerated are able to grow only weakly during fermentation, and the consumption of sugar is also low. The activity of yeast increased with the degree of aeration, reading a maximum level after 5 h of aeration, under the adopted aerating conditions 7."

What's interesting to me is that I typically pitch one pack of 1469, no starter, into 3 gallons of splash aerated wort. I ferment it in a sealed keg with my PRV set to 2 PSI, with no further aeration or oxygenation. This sounds like a recipe for disaster based on the information you've provided. But my beers all attenuate well, and I don't pick up any off flavors. Any idea how I'm getting away with this?

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[RC]

What's interesting to me is that I typically pitch one pack of 1469, no starter, into 3 gallons of splash aerated wort. I ferment it in a sealed keg with my PRV set to 2 PSI, with no further aeration or oxygenation. This sounds like a recipe for disaster based on the information you've provided. But my beers all attenuate well, and I don't pick up any off flavors. Any idea how I'm getting away with this?

Reality astonishing theory would be my guess.

[denny]

What's interesting to me is that I typically pitch one pack of 1469, no starter, into 3 gallons of splash aerated wort. I ferment it in a sealed keg with my PRV set to 2 PSI, with no further aeration or oxygenation. This sounds like a recipe for disaster based on the information you've provided. But my beers all attenuate well, and I don't pick up any off flavors. Any idea how I'm getting away with this?

Reality astonishing theory would be my guess.

Took the words right out of my fingers

[RC]

What's interesting to me is that I typically pitch one pack of 1469, no starter, into 3 gallons of splash aerated wort. I ferment it in a sealed keg with my PRV set to 2 PSI, with no further aeration or oxygenation. This sounds like a recipe for disaster based on the information you've provided. But my beers all attenuate well, and I don't pick up any off flavors. Any idea how I'm getting away with this?

Reality astonishing theory would be my guess.

Took the words right out of my fingers

And for the record, it's your saying ;-) Apologies in advance if I don't always give it a proper citation. It's something I live by as well.

[pete b]

I am embarrassed to admit this but in 11 years of home brewing and all the time on this forum in particular, I have never gotten the "dry yeast doesn't need aeration" memo. I always aerate, usually with a mix stir, before pitching any yeast.
Is aeration at all detrimental when using dry yeast?