amount of washed yeast for a 5 gallon batch

[Elysium]

I am wondering how much yeast I need to put in a 5-gallon batch to have perfect fermentation?

The yeast is going to be washed from another 5-gallon batch and will be stored in 4 jars. I think they are like 1 pint jars.

I know that there is a certain amount of yeast cells I need for a good fermentation...I just dont know how much yeast might be in one jar.

Thanks.

 

[el_caro]

Suggest you use Yeastcalc to assist you in determining how much yeast you need to pitch depending on the volume of your brew and the OG.

You can estimate the volume of yeast you have in a jar by putting same amount of liquid in another like jar and then measuring it.
Depending on how effectively you rinse the yeast it is likely you will have around 2 - 3 bn cells per ml of compacted yeast in the jar.

So for example if you washed the yeast very well and had 50ml of yeast then you could estimate you have around 50 x 3bn = 150bn cells. Now how many of those cells are viable depends on age since fermentation was completed. Yeastcalc will estimate how many viable cells you have and tell you what size starter to make. Or if you are using multiple jars of rinsed yeast just add them up and see what the total viable cells estimate is.

 

[Geordan]

I do exactly what el caro suggested: estimate the volume of the yeast layer (by measuring the height of the yeast strata and determining volume according to the mason jar's diameter) and estimate 2bn/mL for density. Use the "harvest" date when determining viability and you should be close enough for rock and roll!