Author Topic: Yeast Cell Count, Diameter, and BioMass  (Read 1099 times)

Offline klickitat jim

  • I must live here
  • **********
  • Posts: 8604
    • View Profile
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #15 on: July 27, 2018, 11:05:04 AM »
At one point I would read "Amateur brewers get far too wrapped around the axle when it comes to yeast cell counts." And all that stuck was "amateur". Amature? Wha...  who... wha??? I'm angry! Who does this guy think he is? Deep breaths...

Ya, you know what? I was totally going by cell count calculations but totally ballparking the viability of my sample, and not in anyway doing any actual counting. So I started listening and trying and wham, I haven't worried about cell count in about 3 years.

Thanks Mark!

Offline Big Monk

  • Brewmaster
  • *****
  • Posts: 644
  • My name is Derek Scott. I like De Clerck and pH.
    • View Profile
    • Low Oxygen Brewing
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #16 on: July 27, 2018, 11:33:31 AM »
Lager yeast cells also tend to be smaller than ale yeast cells.  That is why I have always prefaced maximum cell density with the word "approximately." Maximum cell density is based on the space between cells while the culture is in suspension, not count.  A smaller cell size results in a higher cell count before maximum cell density is reached.

Amateur brewers get far too wrapped around the axle when it comes to yeast cell counts.  Yeast cultures are truly like nuclear weapons in that close with healthy cells (i.e., cells with good plasma membrane health) is more than good enough because a culture grows exponentially until maximum cells density is reached or the medium is spent.

The reason why high gravity beer requires a larger biomass is because it is more difficult to dissolve O2 in high gravity wort and osmotic pressure is high.  Osmotic pressure occurs when the solution on the outside of the cells has a higher solute (what is dissolved in the solution) level than the fluid inside of the cells.  Water is drawn to the side of the plasma membrane with the higher solute level, which is the wort.  The migration of fluid from inside of the cell to the wort causes the cells to shrink and the cell membrane to lose turgor pressure (turgor pressure holds the cell membrane up against the cell wall), which can result in cell implosion.   That is why it is a good practice to pitch at high krausen instead of waiting for a culture to ferment out.  Pitching at high krausen yields the maximum viable biomass while ensuring that the cells still have strong and pliable plasma membranes due to having good ergosterol and unsaturated fatty acid reserves (UFA).  Waiting until the cells have reached quiescence (fermented out) before pitching results in a brewer pitching cells that have lower ergosterol and UFA reserves; thus, weaker and less pliable cell membranes.  That is why I tell people to ditch the stir plate until quiescence is reached approach that has become fashionable in the last decade or so.  A stir plate does not buy a brewer much when growing yeast biomass because brewing cultures tend to stay in suspension until the sugars that a culture can break down to glucose becomes limiting. What is important is dissolved O2 when the culture is pitched because O2 is used synthesize ergosterol and UFAs during the lag phase.  Anyone who has used pure O2 or the poor man's O2 bottle (a.k.a. SNS) to aerate the medium before pitching understands this fundamental.

FWIW I increase the volume by about 1/3 to 1/2 for lager yeast if I'm pitching around 50°F.  Seems to work right.  I would think that lager yeast is just yeast, and if pitched at say 60°F, it would not need an increase, but would grow sufficiently.  Would be nice to hear from the expert.

Pitching a larger culture with a lager fementation reduces the time to high krausen because yeast cells replicate slower at lower temperatures due to reduced metabolic rate.   The beauty of lager fermentation and why it made industrial brewing possible is because lager yeast can function at lower temperatures than bacteria and other spoilage microflora that are often found in breweries.

And just like that, he's back.

Damn we missed you around here.
“We are what we repeatedly do. Excellence, therefore, is not an act, but a habit.” Aristotle
"Messieurs, c’est les microbes qui auront le dernier mot." Louis Pasteur
Check us out at http://www.lowoxygenbrewing.com/
Check out The Brewing Engine https://brewingengine.yolasite.com/

Offline mabrungard

  • Brewmaster General
  • *******
  • Posts: 2578
  • Water matters!
    • View Profile
    • Bru'n Water
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #17 on: July 27, 2018, 12:13:53 PM »
If there is any doubt, you've erased it...Mark you certainly are an asset.
Martin B
Carmel, IN

BJCP National
Foam Blowers of Indiana (FBI)

Brewing Water Information at:
https://sites.google.com/site/brunwater/

Like Bru'n Water on Facebook
https://www.facebook.com/Brun-Water-464551136933908/?ref=bookmarks

Offline erockrph

  • Official Poobah of No Life.
  • *
  • Posts: 6229
  • Chepachet, RI
    • View Profile
    • The Hop WHisperer
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #18 on: July 27, 2018, 05:20:27 PM »
That moment when one of your team's best pitchers comes off the DL.  ;D
Eric B.

Finally got around to starting a homebrewing blog: The Hop Whisperer

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 20470
  • Noti OR [1991.4, 287.6deg] AR
    • View Profile
    • Dennybrew
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #19 on: July 27, 2018, 06:51:20 PM »
If there is any doubt, you've erased it...Mark you certainly are an asset.

Which is why I contacted him to be in the book!  We want only the best!  ;)
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell

Offline hopfenundmalz

  • Global Moderator
  • I must live here
  • *****
  • Posts: 9197
  • Milford, MI
    • View Profile
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #20 on: July 27, 2018, 06:58:28 PM »
If there is any doubt, you've erased it...Mark you certainly are an asset.

Which is why I contacted him to be in the book!  We want only the best!  ;)

What is the new books title? I have somehow missed that.
Jeff Rankert
Ann Arbor Brewers Guild
AHA Governing Committee
BJCP National
Home-brewing, not just a hobby, it is a lifestyle!

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 20470
  • Noti OR [1991.4, 287.6deg] AR
    • View Profile
    • Dennybrew
Re: Yeast Cell Count, Diameter, and BioMass
« Reply #21 on: July 27, 2018, 08:18:35 PM »
If there is any doubt, you've erased it...Mark you certainly are an asset.

Which is why I contacted him to be in the book!  We want only the best!  ;)

What is the new books title? I have somehow missed that.

I think it's gonna be "Simple Homebrewing: Expert Advice for Brewers of All Levels". 
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts." - Bertrand Russell