Trying to figure out what my problem was on a recent brew. I've narrowed down the possibilities, but I could use some other brewing perspective to avoid this problem in the future.
Waaay back in May 2012 I brewed an ordinary bock, but life, travel, and work intervened to the point that I wasn't able to rack it into a keg until earlier this week. So that made about 8 months of lagering at 41F. I remember nothing about making this beer, as a result, but I have BeerAlchemy statistics recorded for it.
Apparently, I over-estimated efficiency (actually, I think I spilled some of the first runnings) and ended up with OG 1.059 instead of 1.065. When I racked it out, I took a FG reading and thought it would be a little low, since the OG was low. Nope. Instead of 1.016 I hit 1.021!
Tasting the beer revealed no off-flavors. It didn't seem thick enough or sweet enough to justify 1.021, but it was flat and very cold when I tried it, so I will have to try again after it carbs up and see what I've got.
Mashing was apparently done at 154. Thats what the recipe says. I made no note at the time of mashing any higher. The grain bill included:
9lb 13oz Munich (of the german variety 5-6L)
11oz Caramunich 60L
10oz Caramel 120L
10oz Carahell 10L
Did I perhaps mash higher than 154, or was there not enough diastatic power in the grist for the Munich to convert itself and the carahell? Right now I think it must have been a combination of the two, but even then I'm surprised the FG is 5 points high, when the OG was 6 points low.
Another possible factor: the yeast was a strain I never used before, WLP940 Mexican Lager which BeerAlchemy estimates at 70-78% attenuation and "produces crisp, clean lagers". My initial taste test agreed it was crisp and clean. The yeast had been stepped up by making a steam-beer batch that had some acetaldehyde problems (probably from under-pitching). So the yeast could have been unhealthy, but taste-wise they seem to have done their job.
If I learned anything from this site, its that when something didn't work out the way you expected, it often still works out. Seems like it will be a good batch, just wondering why I had so little control on the process this time around.