Acetaldehyde in Lager

[thestraw0039]

I brewed an Oktoberfest on 6/11. Recipe was:
5 lb Munich Malt
5 lb German Pilsner 2 row
1 lb Caramunich malt
1.75oz Hallertauer 60 min
0.25 Hallertauer Flameout
2 Packs W34/70 dry yeast

Expected OG 1.052

Mashed at 152 for 60 minutes, hit my number, pre-boil gravity 1.047 (expected 1.046) and hit a final post boil gravity of 1.058. Had something going on that day so got down to ~120 and threw it in the bucket and put it in my fermentation chamber to chill to pitch temp (55F). The next day I pitched at 55F, see graph below for fermentation schedule. After the cold crash you see I still didn't have a keg available and wanted to brew another beer so I took the beer out of the fermentation chamber and left it at room temperature (~66F) until July 23 when I kegged it.

When I opened the bucket to transfer I was hit with this very strong smell, which my novice nose and palate described as date like. Thinking it was the caramunich malt I kegged the beer. It wasn't my best transfer and definitely got some trub in the keg accidentally. I decided to have the guy at my LHBS try a sample and figure out whats going on and his trained palate figured out it was acetaldehyde.

So at this point I don't what to do. It's currently sitting in my keezer at 38F lagering, but I am wondering if I should take it out and let it sit at room temp for some more. I am planning not touching this until October, but am wondering if the yeast will take care of this at lagering temperatures or does it need to be warmer?

 

[LLBeanJ]

Warm it up. The yeast need to be active to clean it up, but at lagering/serving temps, they're going to be dormant and settling out.

 

[casualbrewer]

Acetaldehyde is green apple flavor. Date like or raisin like would be appropriate for the caramunich. If you can't taste green apple then it isn't acetaldehyde.

 

[helibrewer]

It does not sound like acetaldehyde, I wouldn't assume that the LHBS guy is a trained sensory person.

I agree that you might be picking up the caramunich, it is about 10% of your grist. That beer sat at room temp for plenty of time to do it's clean-up thing, almost 3 weeks based on your graph.

How does it taste carbed up?

 

[thestraw0039]

I just poured a pint of it, and this flavor is all you get on the nose, it is very overpowering. Taste is similar, this flavor is very overpowering and it dominates the palate. I have also never experienced green apple smell and/or taste so I am really flying blind on this, I am assuming that acetaldehyde tastes like a green apple jolly rancher. My novice nose/palate still says it is more date like but I can see the green apple. I got the recipe off of here, but after researching more I realized that 10% Caramunich malt was probably way too much, most recipes were in the 4% range. Also when I got my malt guy asked me if I want Caramunich I, II, or III. I was totally thrown off by this not realizing there were different types, and I think I went with II.

The guy at the LHBS isn't a certified judge, but I have gotten to know the guy and he knows his stuff. I have also tasted a lot of his beer, they have a 5 tap keezer in the store that he does pretty much all of the brewing and it is all pretty good. Obviously doesn't mean a lot, but he knows more about brewing than I do. I think there is a competition coming up maybe I'll try and enter it to get some feedback.

 

[casualbrewer]

Chances are you just don't like or appreciate that style of beer yet. Better for colder weather if you ask me. Probably is a little bit cloyingly sweet at 10%. The darker malts and crystal malts tend to start tasting like raisins or dates the darker they get.

 

[Lefou]

I am assuming that acetaldehyde tastes like a green apple jolly rancher.

...or a sharp Granny Smith flavor. You're 100% correct on that.

When I was doing extract acetaldehyde flavors were evident during bottle conditioning and carbonation. Aging the young beer usually took care of that, but if you're lagering it slows that process down considerably.