building up my yeast slurry

[fluketamer]

i currently have been repitching the whole yeast cake( trub hop matter and all) with good results. but its a discontinued yeast and i want to increase the amount i have so that i can split it into two 5 gallon batches.

i recently learned that i have to repitch it into higher gravity wort to increase the cell count.

do i have to wash it first or can i just repitch the cake into a higher gravity wort to get more yeast for future batches.

 

[VikeMan]

Half a relatively fresh yeast cake from a 5-gallon batch is more than enough yeast for a new 5-gallon batch, unless it sits around too long. Is there a particular reason you need a full yeast cake for each batch?

 

[fluketamer]

the harvested cake has been small it just barely fills up two 8 oz mason jars. i have been repitching the two jars minus the really thick sludge at the bottom (about 1/4 inch) . it has been working really well. i assumed i wasnt overpitching because of this. i am afraid if i pitch just one of the jars it wont be enough since both have been doing such a good job.

 

[VikeMan]

the harvested cake has been small it just barely fills up two 8 oz mason jars. i have been repitching the two jars minus the really thick sludge at the bottom (about 1/4 inch) .

That's a lot of yeast. I think you'd be surprised with the results from half of that.

 

[fluketamer]

thanks i will try half the pitch rate.

 

[CascadesBrewer]

thanks i will try half the pitch rate.

I tend to go by a general rule of thumb that if you pitch 200B cells into a 5 gal batch of an ale, you will end up with 800B cells total in the yeast cake. So pitching 1/4 of the total cake into a following batch will get you back to a 200B cell pitch. It is far from exact, but it has worked for me.

I follow the general harvesting and storage method described in the pinned post:
https://www.homebrewtalk.com/threads/simple-yeast-storage-procedure-with-photos.579350/