Pentainedione question.

[Beeragent]

So after focusing solely on brewing lagers over the last two years, I've narrowed down what I believe to be the common off-flavor in my lagers. I've always thought, regardless of the recipe, that there was a strong honey aroma and flavor to the beer. I could never taste any hops and the malt flavors (grainy, bready, ect.) were never there. I've read all of the posts pertaining to pentainedione, and it sounds exactly like the issue I'm having. Unfortunately none of the posts mention how to deal with it, as it appears a diacetyl rest has no affect on its removal/reduction. I'm honestly not sure if an infection is causing it, or just a technique I'm using. Does anyone have any further information regarding on how to deal with this issue or what causes it? Stressed yeast, copper chiller, water profile, ect.? Thanks for any insight into this problem.

 

[VikeMan]

Pentanedione (i.e. 2,3-pentanedione) is formed by an oxidative reaction that happens in the wort/beer. It's then normally broken down by the yeast (assuming it's formed while the yeast are still active). If you're having a major issue with it, I'd suggest looking at two areas...

- Yeast Health/Pitch Rates, to ensure enough healthy yeast to clean up the 2,3-pentanedione produced.
- Oxygen pickup in wort/beer any time after initial aeration (for yeast pitch).

 

[suregork]

I'd say it's quite unlikely your problem is 2,3-pentanedione. Diacetyl (2,3-butanedione) and 2,3-pentanedione are formed as byproducts of the same amino acid synthesis pathway. Typically a fermentation will produce similar amounts of both compounds, and these are also removed from the wort/beer in a similar fashion. However, 2,3-pentanedione has a 10 times higher flavour threshold than diacetyl. Hence, it's very unlikely you would have a problem with 2,3-pentanedione and not diacetyl.

 

[Qhrumphf]

Sounds like oxidation is the likely culprit to me.