Originally Posted by hercher
As an FYI, a Wyeast propagator pack is designed to inoculate 5 gallons of standard ale wort with slightly less than 6 million cells per milliliter of wort. This is consistent with rates indicated by Hough, Briggs et al., Malting and Brewing Science, volume 2.
I'm afraid that is well known to be an over-simplification. It is certainly inconsistent with the findings of Bamforth and other, more modern brewing scientists (don't forget that resource is 20+ years old), as well as decades of practical brewing experience.
"6 million cells per milliliter of wort" might be perfectly all right in a narrow set of circumstances, but not as a standard
. The brewery standard "rule of thumb" is one million cells per ml of wort per degree Plato. 6M/ml is appropriate for a beer of 6°P, or SG 1.024. I think no one can argue that 1.024 is an appropriate OG for "standard ale".
JZ and other well-known brewing luminaries have proved, and I have also found, through instrumental observation and experimentation that the yeast companies' claims of "pitchable" are at best optimistic. If you're not going to believe brewing scientists, brewing luminaries, or me - a professional brewer and brewery consultant - I don't blame you, though I'll argue you're taking an "appeal to authority" denial a bit too far.
All you need to prove it yourself is a microscope, a haemocytometer and some methylene blue stain, which will permit you to do your own cell counts on random samples of yeast packets. Then you can analyze test ferments based on the manufacturer-recommended technique of direct pitching, as compared to a control of ferments inoculated with "rule of thumb" cell-count samples. You'll arrive at the same important observation as we did: No
package of liquid yeast presently available to the homebrew market contains enough viable, active yeast to properly inoculate a reasonable-strength wort in a standard 5 US gallon brew length.
As you note, one can achieve a ferment if you just pitch a smack-pack. However, that's so far from best brewing practice as to be laughably naive. It is exactly equivalent to the old advice of just pitching "brewer's yeast"; it is advice/technique that's years
out of date.
It's impossible for me to fathom that the same people who obsess over ounces of grain, water chemistry and the potential AA% IBU calculations of hops will just chuck in a smack-pack and think they're doing something not
half-arsed. We are engaged in a hobby with the intent of making the best possible product; deliberately engaging in practices which prevent
us from reliably achieving that goal can be politely described as self-defeating. If one is going to spend hours and lots of money on this hobby, one is an idiot if he doesn't make every possible effort to maximize the result of that work and expenditure.
The only way to RDWHAHB is to follow best practices whenever possible.