Pitch rate for washed yeast

[declanhalpin]

Hi all,

I've been washing and repitching yeast with great success. I'm pretty sure I'm over pitching, so i guess I have 2 questions:

Is there any way of determining how much yeast is "appropriate" using washed yeast?

And is there any danger of actually "over pitching"?

Tx,

DH

 

[diS]

You can use Mr.Malty to determine pitching rate:
http://www.mrmalty.com/calc/calc.html

There is tab "Repitching from slurry" for washed yeast.

 

[ThePearsonFam]

There is no 'danger' for overpitching but it will affect the flavor profile of your beer. Best case is no flavor difference, most-likely it'll be low ester production (significant for ales) and worst case is possibly higher fusel (alcohol) flavors. You should aim for the correct pitching rates and Mr. Malty's calculator is probably the best tool we have to use (unless you have a hemocytometer sitting close by to count cells). I wash my yeast and put the collected cells into sanitized mason jars for refrigerated storage (I typically only store for < 1 month). The mason jars have graduated ml markings on the side that correspond to the Mr. Malty pitching rate output. Just be sure to use the date that your LAST beer finished fermenting (most active fermentation, not when you washed it).

For example, I made a 1060 IPA and used the WLP001 yeast for it. I washed and collected the yeast. Had I used it right away for a comparable beer, then I would've need about 185ml of the yeast. I waited about 1 month before using it and the calculator said I needed ~ 350ml by then (viability of the yeast decreased).

 

[ThePearsonFam]

oh, by the way, Jamil says to leave the settings on 'default' for repitching since they best approximate what you have for yeast cells.

Lastly, if I have 400ml of yeast in a mason jar and need 200ml of it, then I just shake it up and pour half into the wort... Sorry if that sounds simple, I just want to help.

 

[declanhalpin]

Thanks you guys!