Friday, February 13, 2009

Yeast 103

I got a new package of Wyeast 1272 yesterday. I have a long weekend, 4 days off, so I'm planning to brew. I want to do a 10 gallon batch, and single package of yeast won't be enough. I checked Jamil's 'Mr Malty Pitching Rate Calculator' for the quantity I'd need. This is a great calculator, although experience shows that it's generally okay to go with somewhat less yeast that the calculator says. In fact, the Wyeast package says it contains 100 million cells and is designed for a 5 gallon batch, compared to the calculator saying I should have 225 million cells. For a 10 gallon batch, which is what I want to do, the calculator says I need 450 million cells, as opposed to 2 packages containing a total of 200 million cells. I figure if I can get anywhere above 200 million cells in my starter, I'll be okay. After playing with the calculator for a while, I can get 300 million cells in 3 quarts using 1 packet of yeast. It's probably not optimal, but it'll be good enough, and I only need one packet of yeast.

I thought I had some wort saved from a previous batch in my fridge in the garage. I did, but it wasn't enough, and worse, it was old and starting to mold. I tossed it out. I didn't have any LME or DME on hand, so I ground 3/4 pound of 2-row, put it in a grain bag, and mashed it on the stove in a gallon of 155F water for about half an hour. This should get me right at 3 quarts of wort with a gravity of about 1.028, which is enough for a starter. In fact, that turned out to be just right. After mashing, I boiled the wort for about 15 minutes to make sure it was sterilized. After it had cooled to about 70F, I pitched the yeast, gave it a good stir, then split it out into mason jars. I don't have a stir plate, but just shaking the jars every now and then is good enough. After just a couple of hours, there is plenty of activity in all of the jars. I used 4 jars to hold the 3 quarts, so there is plenty of head room, which minimizes the risk of exploding jars or oozing out the tops.

As with any brewing activity involving yeast, sanitation is critical, so I make liberal use of Starsan. I keep it mixed in a spray bottle, which is real handy for sanitizing the outside of the yeast packet, the mixing spoon, and the scissors I used to cut open the packet. All the jars, lids, and rings were also liberally covered with Starsan.

I should be all set to brew tomorrow or Sunday.

Update -- I've got real strong activity, and I'm worried about the mason jars. I sanitized a 2 gallon plastic jar (food grade) and dumped all the jars into the big one. Plenty of head room in the 2 gallon jar, so no worries of foaming all over the place.

I pitched this into batch 71, Panama Red.