Author Topic: Yeast Mutation  (Read 1994 times)

Offline TXFlyGuy

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Re: Yeast Mutation
« Reply #30 on: December 05, 2020, 04:11:39 PM »
Do you know the volume of these fermentation vessels in hectoliters?

Very large. Not sure about the size. Perhaps two or more stories in height.

That is a lot of hydrostatic pressure.  That is the problem with tall, cylindroconical fermentation vessels.  They place significant hydrostatic pressure on what is in the cone.  People who dive experience hydrostatic pressure.  If one examines the breweries known for repitching, volume is increased not by growing fermentation vessels up, but by growing them outward.

So as home brewers we are causing issues with tall conical type ferment vessels?
I have seen large, flat, shallow, open air ferment tanks in a few breweries in the Old World.
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Offline denny

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Re: Yeast Mutation
« Reply #31 on: December 05, 2020, 05:06:25 PM »
Do you know the volume of these fermentation vessels in hectoliters?

Very large. Not sure about the size. Perhaps two or more stories in height.

That is a lot of hydrostatic pressure.  That is the problem with tall, cylindroconical fermentation vessels.  They place significant hydrostatic pressure on what is in the cone.  People who dive experience hydrostatic pressure.  If one examines the breweries known for repitching, volume is increased not by growing fermentation vessels up, but by growing them outward.

So as home brewers we are causing issues with tall conical type ferment vessels?
I have seen large, flat, shallow, open air ferment tanks in a few breweries in the Old World.

No, because ours are smaller volume.
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Offline Saccharomyces

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Re: Yeast Mutation
« Reply #32 on: December 06, 2020, 05:45:27 PM »
That is a lot of hydrostatic pressure.  That is the problem with tall, cylindroconical fermentation vessels.  They place significant hydrostatic pressure on what is in the cone.  People who dive experience hydrostatic pressure.  If one examines the breweries known for repitching, volume is increased not by growing fermentation vessels up, but by growing them outward.

So as home brewers we are causing issues with tall conical type ferment vessels?
I have seen large, flat, shallow, open air ferment tanks in a few breweries in the Old World.

As Denny mentioned, our volumes are not large enough to exert much in the way of hydrostatic pressure.  If temperature is maintained, the average amateur brewers places little in the way of environment stress on a yeast culture, which is why we should be able to serially repitch bottom-cropped yeast if care is made to ensure that average cell age remains young.  The major problem with bottom-cropped yeast is wild microflora ingress.  Top-cropped yeast is much cleaner in terms of wild microflora because wild microflora does not floc to the top. However, few brewing cultures are true top-croppers these days due to the extensive use of cylindroconical fermentation vessels and I have yet to see a Sacharomyces pastorianus culture floc to the top. 

That being said, I am currently reading "Lager" by Dave Carpenter.  The book is beautifully put together, but sadly, it has erroneous information with respect to top-cropping.  The author states that top-cropping involves harvesting yeast from krausen and that the practice leads yeast that has lost its ability to flocculate, which is about as incorrect as one can get.   First off, the rocky brown head that forms first is skimmed.  There is very little in the way of re-usable yeast in the brown head.  However, the second head that forms it almost pure yeast that has flocculated. A lot of brewers conflate flocculation with sedimentation.  Even non-flocculent yeast strains will eventually sediment if given enough time.  Flocculation is the aggregation of yeast cells into flocs.  Most brewing cultures fall into the NewFlo flocculation phenotype.   Flocculaton occurs in NewFlo cultures after the sugars mannose, glucose, sucrose, maltose, and all of the polysaccharides that can be reduced to one of these sugars have been exhausted, which is why spinning a yeast culture to keep it in suspension demonstrates a fundamental lack of understanding of brewing yeast culture biology.  Flocculation is inhibited as long as mannose is in solution because mannose binds to the protein-saccharide receptor that is involved in flocculation.  We can think of this receptor as the yeast cell wall equivalent of Velcro. What differentiates true top-cropping brewing cultures from the rest is that they entrap CO2 gas when they floc, which is which why they rise to the surface.  What keeps a top-cropped culture from becoming powdery (non-flocculent) is the practice of taking the middle head.  If we discarded the middle head and kept the last head, our culture would become progressively more powdery.

Offline Qzm

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Re: Yeast Mutation
« Reply #33 on: December 14, 2020, 03:30:01 PM »
As Denny mentioned, our volumes are not large enough to exert much in the way of hydrostatic pressure.
To put it another way:

If you take a typical homebrew in a conical fermenter and measure the absolute bottom-most molecule, you will find it has ~21kg* sitting on top of it.

Take the equivalent molecule from 1000l conical of the same batch, and it has more than* a literal tonne weighing down on it (and that much fits in roughly a cubic yard, for visualisation).

There's more complexity to it, certainly, but for the purpose of getting the idea into even the drunkest homebrewer's head... it's enough to use the imagery of carrying a sack of grain versus carrying a car. That should be enough to grasp that the home and commercial situations are subtly different :P.

*Twenty liters multiplied by a specific gravity of 1.06.

Online hopfenundmalz

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Re: Yeast Mutation
« Reply #34 on: December 15, 2020, 12:57:53 AM »
As Denny mentioned, our volumes are not large enough to exert much in the way of hydrostatic pressure.
To put it another way:

If you take a typical homebrew in a conical fermenter and measure the absolute bottom-most molecule, you will find it has ~21kg* sitting on top of it.

Take the equivalent molecule from 1000l conical of the same batch, and it has more than* a literal tonne weighing down on it (and that much fits in roughly a cubic yard, for visualisation).

There's more complexity to it, certainly, but for the purpose of getting the idea into even the drunkest homebrewer's head... it's enough to use the imagery of carrying a sack of grain versus carrying a car. That should be enough to grasp that the home and commercial situations are subtly different :P.

*Twenty liters multiplied by a specific gravity of 1.06.

Volume doesn't factor in to hydrostatic pressure.

https://www.engineeringtoolbox.com/hydrostatic-pressure-water-d_1632.html
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Offline Qzm

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Re: Yeast Mutation
« Reply #35 on: December 15, 2020, 02:27:58 AM »
Volume doesn't factor in to hydrostatic pressure.

https://www.engineeringtoolbox.com/hydrostatic-pressure-water-d_1632.html
I've not studied fluid mechanics in the slightest, but my understanding was that mass is what we'd be most concerned with here (given that we can't do much about gravitational acceleration, and we're buying off-the-shelf conical designs :P). Pressure may be the relevant unit of measurement regarding the cells, but expressing it as weight is not exactly wrong*, though the conceptualisation I presented is obviously a gross simplification and explicitly specific to a theoretical lowest, narrowest possible point (higher points will have lower pressures/less force being applied).

The thrust of my post was to illustrate why people don't have to worry about it in homebrewing, rather than to elaborate how it works.

*Though one should really give weight by area, in order for it to actually be convertible.

EDIT: And I am assuming we're brewing in incompressible fluids. If not, I'd love to see a vlog on the process :D.
« Last Edit: December 15, 2020, 06:35:02 AM by Qzm »

Offline Saccharomyces

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Re: Yeast Mutation
« Reply #36 on: December 18, 2020, 12:17:59 PM »

Volume doesn't factor in to hydrostatic pressure.

https://www.engineeringtoolbox.com/hydrostatic-pressure-water-d_1632.html

However, fermentation vessel volume does play a role in hydrostatic pressure due to the fact that breweries tend to want to maximize floor space, which means growing fermentation vessels up instead of out.  Let's compare 5.22 gallons of wort in a 6-gallon plastic carboy versus 5.22 gallons in a 2" diameter, 32' high cylindrical fermentation vessel (3.14 * 1 * 1 * 32 * 12 / 231 = ~5.22 gallons).  The yeast cake on the bottom of the plastic plastic carboy experiences less than 1.42 psi of hyrdrostatic pressure whereas the yeast cake at the bottom of the 2" diameter fermentation vessel experiences over 42.7 psi of hydrostatic pressure.  The moral of the story is that if one has space, it is better to grow fermentation vessels out than up.  That recommendation not only applies to hydrostatic pressure, but also to heat dissipation and O2 pickup. Let's look at Anchor.  Anchor open ferments in what are basically coolships for the very reason that wort used to be cooled in coolships; namely, the high surface area to volume ratio afforded the original Anchor brewers better heat dissipation than other fermentation vessel designs during a period of time when mechanical refrigeration was a luxury.  Today, that style of fermentation is part of the flavor profile.

Offline Cliffs

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Re: Yeast Mutation
« Reply #37 on: December 18, 2020, 04:45:26 PM »
unfortunately Anchor Steam doesnt seem too preoccupied with how their beer tastes these days. I live somewhat close to the brewery and can get fresh examples and it has declined greatly in the last few years.

Offline Saccharomyces

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Re: Yeast Mutation
« Reply #38 on: December 19, 2020, 01:09:25 PM »
unfortunately Anchor Steam doesnt seem too preoccupied with how their beer tastes these days. I live somewhat close to the brewery and can get fresh examples and it has declined greatly in the last few years.

I was wondering what the Sapporo purchase of Anchor would do to the beer.

Offline TXFlyGuy

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Re: Yeast Mutation
« Reply #39 on: December 19, 2020, 02:03:08 PM »
unfortunately Anchor Steam doesnt seem too preoccupied with how their beer tastes these days. I live somewhat close to the brewery and can get fresh examples and it has declined greatly in the last few years.

I was wondering what the Sapporo purchase of Anchor would do to the beer.

Let's hope the result is not the same as when Miller purchased the Celis Brewery, in Austin, Texas. Celis brewed wonderful Belgian beers. But after the purchase was made, the brewery was scuttled.

Recently, the original owners somehow obtained the rights to the building, and started the brewery up again, but it is a shadow of what it used to be.

As I do not consume wheat beers, I was not a fan. No idea what yeast they use, or if the yeast tends to mutate in their brewery.

https://www.celisbeers.com/
« Last Edit: December 19, 2020, 02:04:51 PM by TXFlyGuy »
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Online hopfenundmalz

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Re: Yeast Mutation
« Reply #40 on: December 19, 2020, 03:54:22 PM »

Volume doesn't factor in to hydrostatic pressure.

https://www.engineeringtoolbox.com/hydrostatic-pressure-water-d_1632.html

However, fermentation vessel volume does play a role in hydrostatic pressure due to the fact that breweries tend to want to maximize floor space, which means growing fermentation vessels up instead of out.  Let's compare 5.22 gallons of wort in a 6-gallon plastic carboy versus 5.22 gallons in a 2" diameter, 32' high cylindrical fermentation vessel (3.14 * 1 * 1 * 32 * 12 / 231 = ~5.22 gallons).  The yeast cake on the bottom of the plastic plastic carboy experiences less than 1.42 psi of hyrdrostatic pressure whereas the yeast cake at the bottom of the 2" diameter fermentation vessel experiences over 42.7 psi of hydrostatic pressure.  The moral of the story is that if one has space, it is better to grow fermentation vessels out than up.  That recommendation not only applies to hydrostatic pressure, but also to heat dissipation and O2 pickup. Let's look at Anchor.  Anchor open ferments in what are basically coolships for the very reason that wort used to be cooled in coolships; namely, the high surface area to volume ratio afforded the original Anchor brewers better heat dissipation than other fermentation vessel designs during a period of time when mechanical refrigeration was a luxury.  Today, that style of fermentation is part of the flavor profile.

It is still specific gravity times acceleration of gravity times height that determines the pressure. I get your point on vessel geometry. There is also the square vs round designs, the round ones are used for Weißbier in Germany, I've seen many square ones for lagers.

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Offline Saccharomyces

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Re: Yeast Mutation
« Reply #41 on: December 19, 2020, 04:07:21 PM »
It is still specific gravity times acceleration of gravity times height that determines the pressure. I get your point on vessel geometry. There is also the square vs round designs, the round ones are used for Weißbier in Germany, I've seen many square ones for lagers.

Yes, it is still a specific gravity times acceleration of gravity times height problem.  However, the takeaway here is that the volumes of wort amateur brewers make are too small to have to make the height versus width trade off that designers of commercial breweries have to make.  Any commonly used fermentation vessel at the amateur brewing level is not going to place much in the way of hydrostatic pressure on fermenting beer. Hydrostatic pressure does have an upside; namely, reduction in ester production.

Offline ynotbrusum

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Re: Yeast Mutation
« Reply #42 on: December 21, 2020, 12:06:10 PM »
Brewing under pressure has many advocates.  I wonder about yeast pitches and repitches at say, 12 or 15 psi - how well the yeast holds up....
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