Patrick Hower (220.127.116.11)
|Posted on Friday, August 15, 2003 - 05:15 pm: ||
Looking at Designing Great Beers by Ray Daniels, the optimal pitching rate for 5 gallons is between 200 - 400 billion cells. Based on the Wyeast website, a 50ml smack pack has between 15 and 18 billion per 1.75oz. If I step up this 50ml smack pack to 1 pint and then to 1/2 gallon, by my calculations, I would have ~40 times the amount or ~600 billion cells. If I pitch this 1/2 gallon starter into 10 gallons, I should have the optimal pitching rate. Any issues with my calcs or assumptions?
Bill Pierce (18.104.22.168)
|Posted on Friday, August 15, 2003 - 05:44 pm: ||
You're basically correct. In general I assume about 250 billion cells to be more than sufficient for a 5 gallon batch of normal gravity. Obviously most homebrewers underpitch and still manage to achieve adequate results, but you can see just how little yeast even the so-called "pitchable" tubes and vials contain compared to the optimum population.
As for overpitching, you can pitch up to about 10 times the optimum without problems, so this is not really a concern for the homebrewer. In fact the late Dr. George Fix used to recommend up to 3-4 million cells per milliliter of wort per degree Plato of gravity (almost a trillion cells for a typical 5 gallon batch).