1 Gallon Batch, How much yeast?

[spazzy]

Hey everyone, I just bottled a 3.5 gallon batch of Graff on tuesday, I successfully washed the yeast into two pint size canning jars, (all I had on hand at the time). I am planning on brewing a small batch (1 gallon) today. How much of the washed yeast should I add? the yeast cake on the bottom of the jar is ~1/4 of the total volume of the jar.

I was thinking of decanting most of the liquid in the jar, filling it up to 3/4 with di water, resuspending the yeasties and then adding half of that solution to my wort.

 

[Calder]

At the end of fermentation a beer will have roughly 6 times the ideal pitching rate of yeast. I generally assume 4 times due to loss of viability of some of the yeast.

Following that reasoning, the yeast you harvested from 3.5 gallons, is roughly 14 times the amount you need to pitch into a single gallon of similar starting gravity. I would say use less than 10% of your harvested yeast.

Or alternatively check-out Mr.Malty.

Remember grossley over-pitching reduces the amount of yeast reproduction, leaving old and stressed yeast to do the work, rather than creating new healthy yeast.

 

[spazzy]

Thanks a ton, I will resuspend and use 10-15% of the volume!

 

[Stephonovich]

At the end of fermentation a beer will have roughly 6 times the ideal pitching rate of yeast. I generally assume 4 times due to loss of viability of some of the yeast.

Where did you hear that thumbrule from? It's good to know; I just used a 1 gallon batch of yeast to make a 5 gallon - had quick action, and some minor blowoff. So I suppose the 1-5 ratio is pretty good.

 

[Calder]

Where did you hear that thumbrule from? It's good to know; I just used a 1 gallon batch of yeast to make a 5 gallon - had quick action, and some minor blowoff. So I suppose the 1-5 ratio is pretty good.

I've seen it a few places. It seems to work for me. And recently noticed in 'Yeast', White & Zainasheff, that when pitching 100 billion cells into 20 liters of wort (1.040 I think), the total cells at the finish is 600 billion. 100 billion = the number of cells in a fresh/healthy vial of White-Labs yeast.

I assume that since I wait a couple of weeks to harvest yeast and it is under a lot of pressure (height of liquid above it), that some of the yeast dies, and I make the assumption that the amount of viable cells at the end of fermentation is roughly 4X the amount required to brew a beer of the same gravity and volume. If you double the gravity, you need to double the amount of yeast.