Rough estimate of yeast primary.

[sampsonh]

I have just put a California common in primary 5 days ago. I used yeast I recycled from a previous batch and ramped up the yeast with a three stage starter as I was really paranoid about having enough yeast.... after 5 days it is down to 1.008 I was hoping to stop at 1.014ish... It was a pale cal comm so I think the beer will be fine- like a weird saison I guess! But I want to know is there a way to estimate yeast levels accurately after washing yeast from trub?

Is there a ball park figure for how many yeast cells would be in a certain volume of yeast?

 

[cswis86]

Roughly 1 billion cells per ml of slurry. I put my yeast in mason jars and they have ml markings. The yeast cake in my jars is normally up to about the 100ml mark so I figure I have about 100 billions cells when make my next starter.

 

[LLBeanJ]

I don't wash yeast from the fermenter, just pitch it straight as-is, and I figure the count to be ~1-1.5B cells/ml slurry. Washed (rinsed, actually) slurry will vary based on how well your washing process is. If it's nearly pure yeast, it can be closer to 4B cells/ml, but I would think it would be hard to get it "clean" enough to have the count up that high. I would settle on a realistic number, say 2.5B cells/ml and base your pitch rate on that. I'm sure it will be close enough.

 

[kh54s10]

I have read that when reusing yeast, successive generations may attenuate better. As far as target final gravity, it is just that, a target. The yeast can't read your directions. They will eat the sugars until they all that they can are consumed. IMO the difference between 1.008 and 1.014 is not that big anyway.

More or less yeast cells will not change how much they can convert. If you want a sweeter beer you can mash a little warmer or change the recipe.

 

[sampsonh]

Thanks for all the replies. I want to freeze the yeast with glycerol as I won't be using it again for a while so after washing I will hang it in a bag in the fridge to let the yeast and trub separate and I will try to just collect the yeast... I think for hybrid style beers the ball park pitch rate is 300bn cells so will try to aim for that in each vial.

I'm not too worried about the target fg but it is actually 1.006 and it still is bubbling away! A California common with a fg of less than 1.004-5 won't be true to style!

Thanks for all the help.

 

[sampsonh]

This is also a good point my mash may have been a little low...