Yeast volume to pitch into a 1 gallon batch

[drsue]

I ordered my supplies a while ago, not realizing my smack packs might not be good by the time I used them. So for my first beer (Hefeweisen) I made a starter with my yeast, giving half to my husband for his 5 gallon batch, stored the next quarter in glycerine in the freezer, and used the final quarter for my 1 gallon batch. That worked.

Next smack pack (Wyeast 1007) didn't grow as vigorously but covered a slant tube in 2 days and eats 1040 wort that I feed it down to 1010. So now, how do I decide how much yeast to pitch into my new 1 gallon batch? I do not have a hemocytometer. I do have several sanitized tubes of settled yeast ranging in size from 10-20 ml of yeast cake.

Any guesstimates or ranges?

 

[Smellyglove]

From my experience with OG about 1.055-65 I needed about 75-ish ml of trub"free" yeast slurry for 25L. You can do the math and probably go lower since your yeast isn't harvested. This was for an ale. I guess you can calculate about 4-5 bn cells pr ml og good settled yeast. I usually do 3 for regular ales, to be on the safe side.

 

[ESBrewer]

This is my rather nonscientific multistep approach. 5ml (just a single colony from a plate pitched in sterile wort)->50ml->500ml in 1.040 wort. Decant and pour the slurry from last step to 1-1.3 gal batch.

You could proceed straight to second or third step if you have enough slurry in a tube. You can pitch 0.5-5 billion cells to the 50ml or 10x more to 500ml (~0.5-1ml of well settled sediment per 50ml or 5-10ml per 500ml). It works for me and it should be a bit on the safe side. Generally, it seems that 1 liter of 1.040 wort can support new growth of roughly 100 billion cells depending on (many factors including pitch rate) but mainly on whether you have stir plate and how well you aerate. Without stir plate it could be more like 50 billion new cells per liter, but even this will be enough in a medium strength 1gal brew.