Estimating Cell Count in Harvested Yeast... Possible?

[GrowleyMonster]

I was just wondering if there is a homebrewer-friendly method of calculating or estimating a per weight or per volume cell count for a yeast sample or starter or harvested slurry.

 

[Bobby_M]

The bigger challenge is knowing the viability. Visual or weight measurement is only good for total cells, not how many of them are alive.

 

[Dland]

If one is going to use fresh yeast, volume does not matter as much as viability. I've never had a problem if adding wort to sealed fermentor form past brews. With my fermentors, I dump the trub yeast solids the day before I rack to kegs. This leaves somewhere around a quart (or liter) of yeasty beer from previous batch. When the next 10 gallons of wort gets added, yeast is always off to a good start within 8 hrs even w cold lager fermentations.

The only times it has not is when more than two weeks passed between batches.

 

[GrowleyMonster]

The bigger challenge is knowing the viability. Visual or weight measurement is only good for total cells, not how many of them are alive.

Yeah I meant live cell count, actually. But no biggie I was just wondering.

 

[HazyBeer]

I was just wondering if there is a homebrewer-friendly method of calculating or estimating a per weight or per volume cell count for a yeast sample or starter or harvested slurry.

With a microscope and hemocytometer. I only know because my son is working on his PHD in microbiology.

 

[GrowleyMonster]

With a microscope and hemocytometer. I only know because my son is working on his PHD in microbiology.

Hmmm.... I need to google the hemo-whatsit. I have a microscope that I use sometimes when honing my razors, but I don't have, and never heard of, a hemocytometer.

 

[GrowleyMonster]

Found this. First, found it on fleabay and pulled the trigger there. Then I found it $10 cheaper on Amazon but I already bought from the fleabay listing. Comes with Trypan Blue and Methylene Blue, too. This is gonna be interesting, even if the data is pretty much of no importance.

 

[PCABrewing]

Found this. First, found it on fleabay and pulled the trigger there. Then I found it $10 cheaper on Amazon but I already bought from the fleabay listing. Comes with Trypan Blue and Methylene Blue, too. This is gonna be interesting, even if the data is pretty much of no importance.

Link?

I'm on the fence about getting into counting.
The cost isn't prohibitive but is it worth it since I am not maintaining a yeast lab.

 

[GrowleyMonster]

Link?

I'm on the fence about getting into counting.
The cost isn't prohibitive but is it worth it since I am not maintaining a yeast lab.

Darn it. I knew I forgot something.

https://www.amazon.com/Rs-Science-I...qid=1642359751&sprefix=trypan+,aps,120&sr=8-2
There are way cheaper ones from China, just the hemo thingie and cover slips, without the reagents and other things, for under $10, but this is a fairly complete kit, it seems.

 

[PCABrewing]

Darn it. I knew I forgot something.

https://www.amazon.com/Rs-Science-I...qid=1642359751&sprefix=trypan+,aps,120&sr=8-2
There are way cheaper ones from China, just the hemo thingie and cover slips, without the reagents and other things, for under $10, but this is a fairly complete kit, it seems.

Yeah the looks like a decent kit. Just need to add a microscope that can hit 400x or better.
The cheaper ones from China probably don't save any money and quality is always an issue.
You need the dye to isolate the dead cells.

 

[GrowleyMonster]

Yeah the looks like a decent kit. Just need to add a microscope that can hit 400x or better.
The cheaper ones from China probably don't save any money and quality is always an issue.
You need the dye to isolate the dead cells.

Got the microscope. Can hit 2000x in theory but actually at that much magnification things get kinda freaky but 400x easy sneezy.

 

[PCABrewing]

Got the microscope. Can hit 2000x in theory but actually at that much magnification things get kinda freaky but 400x easy sneezy.

I think the grid size is geared towards 400x so you can count 5 squares.

 

[tripelthelightfantastic]

Do you have any recommendations on a microscope?
I see Amazon have usb based ones that have some kind of stand from €30, they have magnification upto 2000x but assume there are other factors to consider.

 

[GrowleyMonster]

Do you have any recommendations on a microscope?
I see Amazon have usb based ones that have some kind of stand from €30, they have magnification upto 2000x but assume there are other factors to consider.

2000x seems to be nearly the practical limit for ordinary optical microscopes. I have my doubts that a €30 Amazon USB microscope is going to give you good images at 2000x magnification. A proper laboratory microscope works well at 800x or so. I have never seen a cheap microscope give good images at over 200x. Often the magnification is partly digital zoom, not just optical. Your best bet is to get a proper optical microscope so you know that your images are not digitally zoomed, which does pretty much nothing for you. For honing razors we often use the cheapie fleabay/amazon/aliexpress USB scopes and they work so-so for evaluating and troubleshooting edges. I suspect such instruments would be less than optimum for counting cells on a 2.5 micron grid. Then again, you should get your money's worth out of one from the entertainment value, if nothing else.

 

[Jayjay1976]

Hit up shopgoodwill.com for used microscopes. Its kinda like ebay auctions but all the sellers are Goodwill stores..

I picked up an absolute beast of an Italian postwar unit that was made for US military hospitals. Officine Galileo, I'll post some pics. Got it for $28, shipping was $12.

Eyepieces are 5x and 10x, objectives are 3x, 43x, and 97x. It also has a bladed condenser and a geared transit on the stage.

They have sweet lab gear all the time, I picked up a Corning stir plate couple of years ago, also a source for antique bottle cappers. But keep it on the DL, not many people know about that site.

 

[tripelthelightfantastic]

oops, just realized a typo, it should have been 1000x, either way your points make good sense so will look for something analog with better quality.
Thanks GrowleyMonster and Jayjay!

 

[Jayjay1976]

Anyone still looking for a microscope? Vintage Ernst Leitz Wetzler Germany Binocular Microscope W/Case 486 764 - shopgoodwill.com

 

[tripelthelightfantastic]

If only they shipped to Stuttgart!

 

[Jayjay1976]

If only they shipped to Stuttgart!

Former Esslinger here. I'd be willing to help arrange shipping to you. The struggle is real.

 

[tripelthelightfantastic]

Esslingen has the best Christmas market !
Im in Asperg, not too far from where you were
How long since you lived here?
Thanks for the offer Jayjay, I’ll think about the scope a little more.

 

[ba-brewer]

I used to use the mrmalty calculator and it seemed to work fine for me but it stopped working a while back. there is some information still there that might help.
Mr. Malty Pitching Calculator - The Repitching From Slurry Tab

I ferment clean wort and only get about a pint or less of clean compacted yeast slurry from a 5gal batch, 4oz of that slurry still works for me after a month in the fridge for a 5gal 1050ish ale. After a month I use a portion to build up a new starter from the slurry or a use a new yeast pack.

edit:
not sure where I got all of the information but I have been using this to estimate cells since Mrmalty stopped working
3.825BillionCells/mL of clean compacted slurry when first harvested
50% viable after 1 month and do a linear decrease over 30days to that value

I believe whitelabs says their yeast packets loses 20% viability each month, they are pros and I'm just a homebrewer using mason jars in a fridge so 50% seem reasonable.