cell count vs OG

[derbedeu]

Hello all,

Not sure where to post, also, since my question is rather complicated (I guess) I found no other thread to read. So, I brewed an IPA today and after boiling I ended up with 17 liters of wort. Checking the gravity it showed 1080.

Since on my Safale US-05 is written I can add it to a 20 liters fermenter, obviously I tended to spare some. However, as far as I know there is this rule of thumb on how much yeast one should pitch, 1 billion cells/Plato degree/liter. In my case OG1080 is 19.4Plato, so this basically means 1*19.4*14=271 billion cells.

However, in a 11.5g pack there are like 69 billion cells (6B/g), so my beer would call for 4 packs of yeast, which seems weird.

Any idea what am I doing wrong?

Thanks,
Tudor

 

[helibrewer]

Your math is correct. The Safale literature assumes a much lower OG wort.

 

[Talgrath]

The problem is Safale artificially lists the counts as low. They're actual cell count is around 200 billion per packet, so 2 packets will do it, they guarantee at least 69 billion cells per packet if used by expiration.

 

[derbedeu]

Cheers guys, I appreciate it a lot. Hope it will turn out great! Much obliged.

 

[dstar26t]

There are 20 Billion cells/gram of dried yeast when the package is new. They lose about 2% viability per month (stored cold) and are 90% viable new. If you rehydrate in water, following the manufacturers instructions, you'll wake all of the viable cells. If you rehydrate in wort, you'll lose 50% of the viable cells.