Victory Brewery Question About the Number of Yeast

[zaxsan]

This was the "Friday Fun Question" from Victory Brewery on Facebook.

"Our question of the week is super science geeky (thanks to our Quality Lab Technician, Zach). Let your nerd flag fly and answer this one for us!

What is the average number of yeast cells present in a 200-barrel fermentation tank of Golden Monkey?"


This is the answer that I thought was the best - From Jacob Scheiterlein


‎6 - 10 million yeast cells per milliliter per degree plato

200 barrel x 31 gallons = 6200 gallons

6200 gallons x 3785 ml = 23,467,000 ml

23,467,000 ml x a median of 8 million yeast cells per ml = 187,736,000,000,000

187,736,000,000,000 yeast cells x degree plato for golden monkey (I'm going to just take a guess at around 18 degree = 3,379,248,000,000,000

So a total of 3,379,248,000,000,000 yeast cells in a 200 barrel batch of Golden Monkey.




I actually came up with 3.5 Quadrillion, but this is due to a different deg plato used.

Victoy's answer..........

"Winner: Wnndy XXXXX with a guess of 320 trillion. Actual answer, 325 trillion."







Ok. I now open this up for review. I am WAY confused. Could they be under pitching for a reason? Does Victory have super yeast that work 10x better? Does the fact that it is so large change the calculation?

I questioned Victory on the link and have no response. Any help would be great as I went from understanding yeast to now having no clue what is going on in fermentation at a brewery.

 

[beerkrump]

That 325 trillion is the number of cells needed to pitch. Not the number at the end of fermentation.
For pitching...
(0.75 million cells) X (milliliters of wort) X (degrees Plato of the wort)
or
0.75*23467000*18.5=325,604,625 million cells

 

[zaxsan]

That 325 trillion is the number of cells needed to pitch. Not the number at the end of fermentation.
For pitching...
(0.75 million cells) X (milliliters of wort) X (degrees Plato of the wort)
or
0.75*23467000*18.5=325,604,625 million cells

I do not understand where you come up with ".75"

I see 23,467,000 ml X 8,000,000 cells/ml = 187,736,000,000,000 cells/1 deg plato

187,736,000,000,000 cells/1 deg plato x 18plato = 3,379,248,000,000,000 cells



I am confused with the .75

 

[beerkrump]

The standard calculated amount of yeast needed for a starter is 0.75 million/ml/°P for ale, 1.5 million/ml/°P for lager.

"Jacob Scheiterlein" uses 6-10 million/ml, which may be a guess for the concentration of yeast in an active/finished fermentation.