Lager fermentation

[jeffpn]

Krausen has fallen
Like the first krausen...

Never mind that. Usually I let my lagers sit in the primary for 3 weeks. I brewed a Munich Helles on June 27th. The yeast said I should see activity within hours. I did not. It took a day. I did start it warm, as the instructions said. I think it was 24 hours when I reduced the temp. It took about 48 hours from pitching to see a krausen start to form. A day later, it was good and thick. I looked at it today, and the krausen has fallen. I'm contemplating raising the temp to 68° or so now for a couple days, and then racking and lowering gradually to lagering temp. My question, do you think if I raised the temp to 68° now for 2 days that the fermentation would be complete, based on the variables I stated? I can't really pull a sample to check with my hydrometer. The carboy is too tall. I did buy a baster to draw a sample, but it leaks so badly I can't fill my thief with it. Maybe I'll put a hose clamp on it and try.

 

[Nosybear]

It all deals with the yeast's lifecycle. When you pitch, the yeast actually prefer a warmer temperature than we want to give them but they'll work just fine at lager temps so to get them started, pitch at the high end of their tolerance then once fermentation starts, cool down to the temperature you'd like. When you pitch, the yeast first acclimate themselves to your beer by making the enzymes necessary to digest whatever solution they're in, then, since there's oxygen to be had, start living and reproducing aerobically. They will do so until they run out of oxygen, then switch over to anaerobic respiration. More oxygen means they'll reproduce more and be healthier when they get to the part of their lifecycle that produces beer and there will be more of them. A small pitch will mean there will be more reproductive cycles before the oxygen runs out leading to more off flavors - more yeast is better! Since you pitched warm, I'd recommend raising the temps to 68 degrees for a couple days - it's called the diacetyl rest - to let the yeast clean up the diacetyl formed by the warm pitch.

 

[Ozarks Mountain Brewery]

also remember lagers ferment from the bottom, ales the top. top activity isn't as important in a lager