hot doppelbock - help!

[thedrake]

so I made a doppelbock on xmas eve and pitched a big yeast cake of the white labs german bock yeast from my last batch of scharzbier. it spent day 1 at fermenting away at 50 degrees in my temp-controlled chest freezer. I decided to drop the ferm temp down to 45 to minimize ester production in this big beer. the problem is, I forgot that I had the heating blanket plugged into the temp controller (it's really cold in my garage - I live in Lake Tahoe) and it was set to heat, so my ferm temp ramped up to 70F! I just noticed it this morning (after about 16 hours) and immediately plugged the freezer back in so it's cooling down now and should be back at 45-50F within a few hours. All said and done, it will have gone from 50F to 70F and back to 50F in about 20-24 hours on day 2 of fermentation. My questions are: should I expect this yeast to all drop out and quit on me due to the temperature rollercoaster ride? should I pitch more fresh yeast? did I just produce a bunch of esters, sulfur and hot alcohols and ruin this beer? If so, will long-term cold lagering reduce/eliminate these off flavors?

I've been brewing ales for 14+ years but am new to lagering. I've heard that the german bock yeast is very tolerant of warmer temps...some even say they ferment with it a ale temps and don't have sulfur/ester issues. Anyone out there experienced hot flashes in lager fermentation?? Hoping I didn't ruin this beer...

Cheers, Kevin

[Blunt]

I did a Double Bock earlier this year and had sort of the same thing happen to me I think the temp rise to 66-68 before I lowered it back down. The flavor of the Bock is good but it did get some fusel alcohols. I'm not overly worried about the alcohol flavors because in my past experiences they went away after some lengthy lagering. And hopfullly the primeing sugar can fight thru the high alcohol and find enough yeast to carb the bottles up. I probably should have added some yeast at bottling but didn't. I generally use Fermentis 34/70 for my lagers and have only used WL 833 Bock yeast once and was a good yeast, very malty. Most likely with some extended lagering your beer will turn out fine.

[brewinhard]

That sucks when shit like that happens! It really pisses me off! Anyway, you will probably have some more noticeable esters than typical along with possibly some fusel alcohol production in your finished product. The good thing is that it didn't spend a super long time at those temps. I think your yeast will be okay, although try to be gentler to them in the future, at least with a big ass lager like a Dopplebock! If you are lucky, an extended lagering period will help to reduce some of these esters and clean up your brew a bit. Don't be afraid to leave the beer on the yeast cake a bit longer than usual and give your beer a diacetyl rest (low to mid 60's) to help clean up any off flavors produced by the yeast. Good luck!