How to know how many yeasies I have

I have been washing my yeast from my batches of beer, and have quite the collection going. I have made a starter for previous batches (5 gallon), and have got to an expected final gravity. However, I am going to make a big beer, and I am worried there is not enough yeast. I was using Mrmalty.com calculator, and it says I need 339 billion cells for the 1.091OG...how do I know how many cells I have when I collect yeast from previous batches?? Would I be fine if I just stepped this up once, or do I need to at all? It is just a 5 gallon batch.
Thanks

After you make a starter, you can estimate your cell counts by volume. Wyeast has a volume guide in their Pitching Rate Section. Follow the link and scroll down to the bottom. Puts you in the ball park.

So do I just compare my total starter volume to those vial pictures. Or do I need to suspend my yeast and pull out a 1 ml sample and compare that

It is better to pour some starter (after mixing it well) in test vial, cold crash it and then estimate density by link BBL Brewer posted.
I am using 10 ml graduated cylinder and I estimate before making starter, after yeast settles I count percent of solids in 10ml and then calculate density for starter volume.
After that you can use some of calculators to see how big starter you need.

Short of using a microscope that's probably the best way to do it. Keep in mind it's an estimate, and if you want a clean beer it's probably better to estimate high, and if you want some fruitiness you may consider estimating low. From the cell counts I have done even the cell density of the "yeast solids" can easily vary by a factor of 4. If you use a starter then you eliminate the variability of the "non-yeast" component, and you can fairly safely assume a viability of 95% or higher.

Just to put some numbers on it my WLP004 is about 250 billion cells per liter and my WLP566 packs to a dense 1,750 billion per liter.

Thanks a lot for the responses fellas, this brought up another question though. Say I don't have enough cells, and I need to make another, larger starter, how do I calculate how much DME and water to use for the step up?

I would think yeast calc will get you pretty close. Just turn off the "viability by date" option and enter the number of cells you think you have for the "initial cell count" The experiments used to produce the growth curves were with a 1.036 wort so I would use that.

panfishrfun said:

Thanks a lot for the responses fellas, this brought up another question though. Say I don't have enough cells, and I need to make another, larger starter, how do I calculate how much DME and water to use for the step up?

Click to expand...

That's where this guy comes in handy.

never mind, I didn't read the previous post well enough....

Sorry, I don't know if I really get this...you're supposed to take the washed yeast, and figure out how much yeast you have before you make the starter, then use the yeast calculator to determine the starter size and number of steps used to achieve determined number of cells??

If so, here's a picture of the original washed yeast in a 16 oz mason jar...is there any way from this container to determine how many yeast cells are present?

If i guesstimate there are 100 billion cells (standard setting on yeastcalc) with my original 0.8L starter @ 1.040OG, then, according to the calculator, I need to make another starter @ 1.75L to achieve my 323 billion cells??

325 billion determined from

(0.75 million) X (milliliters of wort) X (degrees Plato of the wort)

750000 X 20,820 X 20.7 = 323 billion

and does the difference in yeast count matter between this equation and yeastcalc suggestion (340 billion)...I imagine it's negligible at this level

Also, just to make sure, the starter volume is post boil correct?

Thick slurry usually have between 2-2.5 billions/ml. You can get a test tube and estimate per wyeast instructions.
Or take same jar and fill it with water to get same level as it is in 1st jar, after that measure volume of water.

From counts on washed yeast from slurries, I have seen less than that. About 250 million / ml to 1.4 billion / ml. The ball park number I have seen is 1 billion / ml if you can't count the cells. (see the "why not pitch on a yeast cake" thread)

just to keep going with this...
assume 1billion cells/mL
the mason jar is 16 oz or ~473mL
so I have 473 billion cells?? and I don't have to make a starter

I'm sorry if this is way easier than I'm making it
for some reason I can't get my head around this

panfishrfun said:

just to keep going with this...
assume 1billion cells/mL
the mason jar is 16 oz or ~473mL
so I have 473 billion cells?? and I don't have to make a starter

I'm sorry if this is way easier than I'm making it
for some reason I can't get my head around this

Click to expand...

It's ML of settled yeast slurry... not the entire starter size.
Start with a known amount of yeast and grow them in a starter.
Cold crash and decant the spent wort.
Measure the yeast slurry left over, and depending on how dense the slurry is, assume about 1B/ML.

WoodlandBrew said:

From counts on washed yeast from slurries, I have seen less than that. About 250 million / ml to 1.4 billion / ml. The ball park number I have seen is 1 billion / ml if you can't count the cells. (see the "why not pitch on a yeast cake" thread)

Click to expand...

This (2-2.5 B/ml) is density of thick portion of slurry so you are correct, when it comes to total density (slurry + liquid above) it is closer to 1 B/ ml.

I'm just saying my experience is different that yours. I count thick slurry as much closer to 1 billion per ml than 2 billion. That also seems to be the consensus that others have come to. (see acid rains's post and the tread I linked) Where is your 2 billion number from?

My procedure is based on white labs method and is here:
http://woodlandbrew.blogspot.com/2012/11/counting-yeast-cells-to-asses-viability.html

As I said I didn't count it, it is estimation based on wyeast suggestion. I contacted them about it and Jess from lab says that it should put me in ball park.

I am open to new cognition's.

I sanitize my dining room table, lay out all the cells and have my 3 kids manually count them, they are all math wiz's:fro:

diS said:

As I said I didn't count it, it is estimation based on wyeast suggestion. I contacted them about it and Jess from lab says that it should put me in ball park.

I am open to new cognition's.

Click to expand...

We are probably just splitting hairs here. In all practicality a factor of two on the cell count is not a big deal. I see a variance by a factor of 6 in density of "thick slurry" and between 60%-97% viability from freshly harvested cakes. This seems to be a common finding by people doing cell counts. The combined error when pitching from a slurry is over 10 times just between these two variables.

I just am trying to understand where the difference comes from. Perhaps the yeast from their lab has much less additional material such as protein. Under the scope I can see that there is about 10-25% as much protein mass as yeast cells. (That's just a complete WAG at it based on relative size. You can see it to the top and right of this image:trub)

Perhaps 1 billion cells per ml is more accurate for slurries, and 2 billion cells per ml is more accurate for the material that comes out of a WYeast package.