Diacetyl

Got a question for you... I brewed a cream ale a while back but fudged the water numbers and ended up with a more concentrated cream ale, very high for style for sure. Anyway it was a 10 gal batch and i got about 4 and 4 (if that) in two fermenters. I used a cream ale yeast (WLP080) in one, and a Pacific Ale (WLP041) in the other. They came out very different (expected) but one just has way too much Diacetyl taste now. Same fermentation temps for both, same primary/secondary regime, my question is.... can Diacetyl come on more overtime? its' been sitting in a keg for a month, never noticed it until now.

 

My null hypothesis is:
Ho: Diacetyl is more prominent with different yeasts
H1: Diacetyl is not more prominent with different yeasts

 

Diacetyl is produced during lag and exponential phase of fermentation (first few days), so according to that, if fermentation is over it shouldn't increase in kegs.
But, different sorts of yeasts produce more or less diacetyl, and I would seek for an answer in that fact.

 

What temp did you ferment both at? Higher temps in general will generate more diacetyl. Also looks like the WLP041 is pretty slow to ferment completely, and likely then slow to clean up its byproducts. I found the article below which is pretty good. It indicates that diacetyl present in your brew will increase with aging. +1 to above on formation during early phases, but if there are still precursors available then further oxygen pickup (moving to keg) can result in more diacetyl production too.

http://www.winning-homebrew.com/diacetyl.html

 

Yes it can. Acetolactate (diacetyl precursor) left over from primary fermentation can slowly oxidize and turn into diacetyl. If the yeast is no longer active (f.e. because completely filtered out, a typical issue in commercial brewing) then the level of diacetyl will actually increase as maturation progresses. If that's the case there's very little you can do to get rid of it at this point except somehow adding active yeast.

Cheers,

Vale

 

Infection will cause the dreaded D. Not saying that is your issue but it certainly is a possibility.

 

You didn't specify, but I bet the off flavor is in the one with the WLP080 cream ale yeast??

That yeast is a blend of ale and lager yeasts, so fermenting it at 65F+, you'd expect to have some diacetyl and sulfer off flavors from the lager yeast portion of the blend.

Just let it condition for a few more weeks than usual, and those flavors should mellow and blend into the beer.

 

I agree I ve been watching my Kolsch closely for the last few weeks on account of it my first try at the style and it was giving off some off smells during primary, but in a few more days of letting it climb close to room tempthe smells as well as the everlasting krausen dissipated ..it just needed some time.

 

Thanks for everybody's response!
Tonight i discovered that the 2nd keg that didn't have diacetyl before, now does. So it appears that regardless of yeast, it has come on over time. Very confused and worried about future brews...
blwitt: I mashed at 154, after 1 hour it dropped 3 degrees to 151.
Vale: so you think the damage was done in primary fermentation and just took a little longer to notice in the 2nd keg?
samc: You have me worried. i'll research infections re: diacetyl.

Thanks all for your time, much appreciated.