Re-using yeast for the first time and pitch rate

[jay3847]

I just did some yeast washing for the first time with WY3522, and am getting ready to make another batch of Belgian Golden Strong. I've read that I should do a starter with the contents of one of my mason jars (ooohh, nice creamy yeast inside) but how do I know how many cells are there without having a microscope for yeast counting? I don't know my starting point and I'd like to do a 1.0 pitch rate.

Set this rookie straight.

 

[J A]

There's a yeast pitch calculator link in the yeast section of the recipe editor. It'll tell you what you need and provide basic guidance with slurry. I use that and cross reference it with the Mr. Malty yeast calculator. That one gives more option for closer calculations based on age of the slurry, thickness, etc.
I pitch straight slurry and it tends to have a fair amount of non-yeast stuff and the BF calculator default count of about 1 billion per ml seems to work out about right with fresh stuff. For older stuff, I adjust downward, consulting the Mr. Malty numbers. If you've rinsed the slurry and carefully separated out the yeast layer, you have very dense yeast count. Maybe twice as much as the BF calculator estimates.
A decent rule of thumb is that the yeast from one batch will do at least 2 batches of the same size and gravity. If it's nice and fresh, it might be adequate for 3 but I think that would be pushing it.
If it's a cool-fermented lager, you need a lot more but the yeast calculator will tell you that, too.

 

[jay3847]

Gravity was 1.085 and the yeast after wash is still quite thick. I'll look at the slurry calculation in BF. The yeast will be about a month old when I use it so I'll take that viability into account.

Thank you.

 

[HighVoltageMan!]

Assuming your golden strong is a 5 gallon batch at 1.090 starting gravity, a 2.5-3.0 liter starter (1.036 gravity) with 2 tablespoons of yeast slurry will give you a 1.0 pitch.

2 tablespoons of yeast slurry contain about 120 billion cells. Punch that into the calculator and adjust the stater size. I would favor a 3 liter starter to error on the side of caution.

That’s my two cents.

 

[J A]

Yeah, if you're doing a 1.090 beer, you need a starter.

 

[GFHomebrew]

Look at the side of your yeast jar how far far up the jar does the white creamy layer go. How many Mills is the Jar every milliliter of yeast is 1 billion cells so 20 mills 20 billion. This is how i estimate my yeast count.

 

[Ozarks Mountain Brewery]

this is pure yeast, a good visual for washed yest, this layer is what you want

 

[jay3847]

Jeez! Who knew there were milliliter measurements on the mason jars. It varied a bit for the three jars, but I had around 120 mls of very thick slurry in each. I saw the slurry option on the pitch calculator and Bingo!

Lastly, I assume the same loss of 20% viability per month, correct?

 

[Nosybear]

Gravity was 1.085 and the yeast after wash is still quite thick. I'll look at the slurry calculation in BF. The yeast will be about a month old when I use it so I'll take that viability into account.

Thank you.

Your yeast is likely to be quite tired after such a big fermentation. Starter, definitely.