Monday, November 30, 2009

Fun and games with WLP925

A lot of people have asked me about the WLP925 yeast that used recently, so I thought I'd provide an update.

First of all, I'm really treating this first batch like a big yeast starter. I had some problems with this past brew, and I don't want to truly evaluate this yeast strain based on this batch. Some of the problems were my fault - screwed up chilling my wort and didn't get it nearly as cool as I wanted when I pitched the yeast. And some of the problems were related to this yeast strain and the new process associated with using it - had some trouble getting my spunding valve dialed in to 15psi, so the pressure on the fermenter fluctuated throughout fermentation.

Also, this yeast appears to be pretty non-flocculant. I had to pitch the entire four liter starter because the yeast just wouldn't settle out to the bottom of the flask. I hate dumping starter wort/beer into the five and a half gallons of wort I've just worked so hard to create. Yet another reason I'll reserve judgement on this batch.

I actually changed up my original plan to do a helles type lager and brewed something more along the lines of a dunkel. It came in at 1.054. When I racked to a secondary last night, it measured out at 1.014. 74% attenuation is about what I would have expected, so I was happy with that result. The beer is also pretty well carbonated since it's been under pressure all this time. That's one of the benefits of using this yeast, but it also makes racking, measuring gravity, and washing yeast a bit treacherous.

As for the sample, it was tough to get a good read on it. It was very cloudy, again confirming my observations that this yeast strain doesn't flocculate well. I'll probably have to do some kind of fining in the secondary, which I'd really rather not do. Especially since the beer is already carbonated. We'll see. Maybe a week at 35F will do it some good.

The toasty malt character that I was going for in the dunkel recipe that I brewed was definitely up front, so that was a very good thing. However, it was very yeasty tasting, which made it difficult to really evaluate well. More on this next week.

No comments: