Starters & Cell Counts

I'll start by saying thanks very much for the FOY opportunity. Recently I saw a note that a 2L starter made using a "vial" of yeast containing 30-60 billion cells would grow to 240 billion cells. Since the note appeared to be general, the assumption would have to be an aerated starter when made and then left to sit with no swirling or further aeration.

A four to eight fold growth seems extremely high to me. Is this reasonable/achievable with no additional agitation or aeration?

Cheers,
Mike Dixon

RESPONSE:

Mike, From a normal fermentation in 12 P wort, aerated at the start, you will harvest 4-5 times the amount of yeast that you pitched at the beginning. An eight fold growth like you found is a bit high but not impossible. It always depends on the yeast strain but more important on the quality of your wort. A well aerated wort that has sufficient amounts of nitrogen and minerals should give you this kind of growth.

Regards,
Tobias & Forbes