SAFALE US-05 Cell Count

[BierCraft]

First time posting, but long-time reader.

After scouring the forums concerning the cell count of one 11.5 gram sachet of US-05, I have found this much out so far:

Fermentis provides a guaranteed minimum (due to legal reasons and to avoid complaints) of 6 billion cells per gram, meaning about 66 billion cells guaranteed.

Sean Terrill: 150 billion at 75% viability re-hydrated

Another site (can't find address): also 150 billion at 75% viability re-hydrated

Mr. Maltly says 220 billion per 11.5 grams.

Other sources: About 150 billion from the forums

Most here seem to get good results with one sachet for a standard five gallon batch with an OG of around 1.050.

I am about to brew a 30 liter/7 US gallons of an Am. IPA with an estimated OG of 1.065. A regular ale would require about 367 billion cells, but a higher gravity ale would require 493 billion. Understandably, 1.065 is on the cusp of regular ale and higher gravity ales.


My questions are:

1.) Does anybody actually know the cell count of a sachet of US-05? Fermentis has not gotten back to me and this is my first time using this yeast.

2.) I am was thinking two sachets would be enough. Thoughts?

3.) Am I overthinking it?

Prost from Germany

 

[eadavis80]

I would say yes to no. 2 and no. 3.

 

[RM-MN]

1. No. Nobody is capable of counting all the cells of yeast in a package so they make a count of a small amount and extrapolate. The numbers they come up with are slightly more accurate than a wild guess.

2. Yeast are live "animals" and given the right conditions they readily reproduce. If you give them the right conditions, even a single package will be enough. 2 packages should be fine if you even try a little to give them the right conditions. To reproduce in your beer, the yeast has all it needs except oxygen to create new cells so aeration is critical. But then, what if you don't have enough cells? Check out this experiment with the right pitch, massive overpitch, and extreme low pitch. Note that all three made drinkable beer. http://sciencebrewer.com/2012/03/02/pitching-rate-experiment-part-deux-results/

3. I'm glad that you are thinking about it. Yes you are overthinking it. Now relax and have a brew.

 

[BierCraft]

Thanks for the replies.

I find it unfortunate that the range could be 66 - 220 billion. When making certain beers this could prove problematic, but I think I will start to utilize the yeast from a previous batch in order to ferment a new batch as I will be brewing often enough.

Thanks for the help. Brew day is on for Wednesday!

Prost from Germany!