BeerSmith™ Recipes and Web Editor
fbellanca 14 Shared, 2 Reviewed
Ixisnine on fbellanca's wall
- 1 July 2012 - 6:42 pm
I started playing with Mr. Malty's on-line calculator, and Mr. Malty calculates viability MUCH more severely than Beer Smith 2. For example, Mr. M says that a liquid yeast dated 5/7 is only 58% viable. If you plug in a date of 6/5 the viability comes up to 78%, and if you put in 6/30 you get to 96% viable. This sure seems to be borne out by what we saw today with the yeast packets' amount of swelling. I don't know if Brad doesn't want to start a shitstorm about yeast freshness, so was more "charitable" in Beer Smith, or if Beer Smith is just broke. But Beer Smith says that yeast with a manufactured date of 5/7 is still at 96% viability. Conversely, maybe Mr. Malty is just wrong. But I think I would prefer to err on the side of pitching enough, even if seems nuts (like 3 packets). Or at the very least, not even consider buying yeast that is more than one month old. Because if we get the yeast fresh enough, Brad Smith and Mr. Malty will be much closer to saying the same thing.
By the way, I'm not sure it it is appropriate to do so, but if you can say that "average viability" is the sum of the 2 viability percentages divided by the number of packets, but if you CAN do that, our viability today might have been around 68%.