Making starter, how many cells in this wash?

[JoppaFarms]

Hey folks, made a pint of extra starter last time I brewed to keep the strain I had. Now I want to use it again to make a starter (with an extra pint to keep). Any idea how many cells to expect in this much so I can calculate starter size with BeerSmith? This is a "normal" pasta sauce jar.

 

[JoppaFarms]

Ok, so someone check my math, if you could be so kind. The last starter I made required 180 billion cells, and with the yeast packet I had meant I needed a 1L starter (2.11 pints). So I made a 1L + 1 pint starter to save the amount in the picture above. So 180 billion cells per 2.11 pints starter is ~85 billion cells/pint. So I'm estimating that I had roughly this much in the jar, then use BeerSmith to calculate the viability from the date on the starter.

So, does 85 billion sound about right?

 

[mbobhat]

You could always estimate the volume of yeast cake at the bottom of the jar as well. Since it is a starter it should be mostly yeast. Just eyeballing it I'd say ya got around 50 mL of yeast cake.

So is your starter 1 pint larger? A little confused there. Your math seems right assuming the yeast continue to grow to 85 billion more with that extra pint added.

 

[JoppaFarms]

Yea, I estimated that with the initial "planned" starter of 1L making 180 billion cells, that came out to 85 billion/pint. I did add one extra pint to that 1L starter, and I am summing that it grew at the same rate, making a total of 265 billion cells in the starter. Of the 1L+1pint starter, I kept 1 pint, which is what is pictured and (unless I hear otherwise) I am going to assume had roughly 85 billion cells in it on the date on the jar. I'll use BeerSmith to calculate viability and starter size for the batch I'm brewing tomorrow.

 

[flars]

I estimate 1 billion cells per milliter for saved yeast when making a starter. Yeastcalc gives a range of 1 to 2 billion per ml. I would rather overpitch than underpitch.

If you have another jar the same size, add a measured amount of water to the same level as your yeast. The measurement can be in ounces or ml. From this you can estimate your number of cells.

There is a really nice conversion calculator available on line to keep on your desktop. Look up 'Josh Madison conversion'

 

[JoppaFarms]

Thanks for the info flars. Unfortunately I don't think I have a way to measure individual ounces or ml of water. I guess I should invest in a graduated cylinder or something.

 

[flars]

Thanks for the info flars. Unfortunately I don't think I have a way to measure individual ounces or ml of water. I guess I should invest in a graduated cylinder or something.

I used a standard pyrex one cup measure. Marked in both ounces and milliters. Rough measurement, but in the ball park.
Came out at the same molded markings on some jelly jars i purchased later.

 

[JoppaFarms]

HAH! Well look at that. Didn't realize my pyrex 1 cup had mL on it. Next time I'll know. Thanks again!