Rinsed Yeast Repitching

[chanson16]

Here is a pic of some yeast I washed. I want to use it in an IPA (1.058) and realize I will need a starter. I have read many threads about it but am still confused of how big a starter I will need.

It seems like all of the calculators require fairly subjective assumptions that can significantly impact whether your starter is adequate or not.

In my case, it looks like i have roughly 1oz of slurry with about half of the slurry being white yeast cells. As a noob, I am not sure how to estimate the cell count (i estimated 3 billion/ml). My calculations say a 1.75L started will yield 230 billion cells (does not reach the necessary 243 billion/ml). However, if I increase the cell count to 3.5 billion/ml then I have enough cells with a 1.75L starter.

Am I overly worried about getting the proper cell count. My concern is that I have far less than 3 billion/ml and will significantly under pitch. Any guidance is appreciated.

 

[PaulVikingAles]

Are you making 5 gallons? If you decanted and pitched the slurry in a 2L starter and put it on a stir plate for 24 hours you should be all set. The viability of the yeast is important and they are probably beat up a bit if you washed them from a prior batch. So far so good. Just grow some more. Are you sure that is only 1oz. The picture must be deceiving. I would guesstimate that you end up with about 100ml's of slurry from a 2L starter. If that is a mason jar then you have quite a bit of yeast.

 

[chanson16]

Are you making 5 gallons? If you decanted and pitched the slurry in a 2L starter and put it on a stir plate for 24 hours you should be all set. The viability of the yeast is important and they are probably beat up a bit if you washed them from a prior batch. So far so good. Just grow some more. Are you sure that is only 1oz. The picture must be deceiving. I would guesstimate that you end up with about 100ml's of slurry from a 2L starter. If that is a mason jar then you have quite a bit of yeast.

It is a 6 gallon batch. The picture is deceiving but the measurements indicate it is just 1oz. I don't have a stir plate and only have a half gallon container for starters.

 

[chanson16]

Would it be safer to use two mason jars of washed yeast? I have another one available and could pitch two if it would help.

 

[PaulVikingAles]

That is a good amount of yeast but I would be concerned with viability and stress levels. A half gallon is almost 2L so I would probably use 2 mason jars with the thought that your viability is lower.

You could grow more yeast by pitch half of that slurry into your half gallon filled 3/4 with starter wort and grow new yeast with that. You will still have the mason jar with some of the yeast and you will grow a good amount with your jugs. Your yeast have finished growing when your jug is fermenting, about 18-24 hours. Pitch all of that slurry into your 6 gallons, including the mason jar.

I would also invest in a Erlenmeyer Flask so you can measure starters and slurry in ml/L. Invest in a stir plate as well. You can diy one for $40 or less depending on your diy skills. We have a diy section on your website at www.vikingales.com

 

[Calder]

My rule of thumb is to pitch about a quarter to a third of the cake on the next batch. And if I do it within a month, I see no reason to make a starter.

Looks like you have a lot of healthy yeast.

You can make your own mind up, but when checking Mr. malty (if that is what you are using), I think it way.... way ...... way over estimates the cell loss with storage. I'd just dial it in as though you harvested the slurry yesterday.

 

[PaulVikingAles]

Agree with Caldor. If you washed enough then pitch it. 1 mason jar didn't seem like enough but 2 of that size should do it.