Beer Forum

Hey all,

My last two batches have had significant diacetyl after fermentation and I'm trying to figure out why...

1st batch was a saison with Wyeast Bier d'Garde yeast - pitched a 2L starter at 68, let temp rise naturally over a few days into mid 70s, then hooked up a brew belt and pushed the temp up to around 80 for another week about. FG was 1.008. Kegged it and it really tastes buttery. I aerated for 1 min. with pure O2...is that too much O2? Also, I used about 30 ibu's of Sterling/Saaz and it has next to no hop bitterness, flavor, or aroma...

2nd batch is Jamil's Golden Strong Ale with Wyeast 1388... pitched slurry from a 4L starter at 65 degrees with same fermentation control as on saison... Still in primary and haven't taken a gravity yet... Planning on putting in the secondary... brewed this last year and it came out fantastic. Same aeration - 1 min. of pure O2. Getting a strong diacetyl smell out of the airlock.

Any suggestions would be greatly appreciated...

Thanks a lot - Chris

It's not necessarily a fermentation issue. High levels of diacetyl are more than likely the result of a bacterial infection.

More Info

clarkbone@mac.com wrote:let temp rise naturally over a few days into mid 70s, then hooked up a brew belt and pushed the temp up to around 80 for another week about.

So you only fermented for 10 days? Give it another week (or two) and see if that helps. Also, don't bother with a secondary unless you have a good reason, leave it on the yeast to clean up the off flavors.

siwelwerd wrote:So you only fermented for 10 days? Give it another week (or two) and see if that helps. Also, don't bother with a secondary unless you have a good reason, leave it on the yeast to clean up the off flavors.

+1
I leave all my ales on the yeast for at least 4 weeks, regardless of style. It helps clean up things like diacetyl, acetylaldehyde, etc. For that matter, I leave the lagers in the primary for at least that long too..
But if it needs further aging, I will rack to a keg at the same temp as fermentation. Otherwise I crash chill that keg and start drinking.

The reason I am posting this is that yesterday I ran the club's monthly competition (VMO and Bock) and, as is the custom, asked each brewer if his beer had a name. One fellow gave me the name "Diacetyl Bomb". When the score sheets were in I looked for his to see if the judges (who aren't given the names) had picked this up. There was no mention of buttery flavor but both panelists mentioned apple like flavors. I went and got the rest of the bottle and tasted it. It should have been called "Acetaldehyde Bomb". It was so strong it was beyond apple-like. It was positively aldehydic (if you've ever smelled pure acetaldehyde you know it does not smell nice - it's only when it is very dilute that it has the apple quality). I'm mentioning this because this is the second contest in which I have experienced this (I was a judge in the other one) this summer and have 2 related questions. 1 Are people confusing acetaldehyde and diacetyl? 2 Is there some sort of nasty acetaldehyde producing bug going around in these parts?

In any event if diacetyl is strong enough to smell/taste butyric or the acetaldehyde aldehydic then the source of the problem is infection ("sarcina sickness" in the case of diacetyl) and no amount of time on the yeast is likely to cure it.