Bitter Almond

[Thomas Fransson]

A week ago when i sampled a keg of my barley wine i noticed a kinda bitter almond flavour in it...
The keg have been outside and might have frozen a bit, like ice beer during a couple of cold nights...

What could cause this kind of off flavour, it ought to be a fermentation issue?
Insufficient aeration, bad yeast, bad yeast selection?

I used 2 packs of Windsor dried yeast for aprox 15 liters OG 1.94
Roused the yeast to get down a couple of points in the end, cant remember my FG thou.

Any suggestion on how to avoid this in the future?

[ajdelange]

I'm guessing, and it's no better than a guess, that it is benzaldehyde which is a major component of bitter almond oil and perhaps benzyl alcohol which is a fusel and which, when oxidized, would convert to benzaldehyde. If I'm right the standard techniques of lowering fermentation temperature to minimize fusel formation and limiting exposure to oxygen/air to prevent oxidation of any fusels that form to their aldehydes would be the way to minimize these flavors.

[Thomas Fransson]

Thanks for your thoughts and guesses on this one!
Googled on it and like you say benzaldehyde was the only thing that came up that sounded like a possible answer.

I think i can exclude ferm temp on this one since i fermented farily low.
Guess the problem is the yeast and fermenting in plastic being a bad combo. (there's no carboys in sweden)
This brings me one step closer to look up the cost of getting a few conicals made by a local company

[Spelt]

Bitter almond is also the most common descriptor for cyanide. Better drink that beer REAL slow.

[ajdelange]

Barley, as is the case with many plants, contains some cyanogenic glycosides and germinating barley sometimes even contains free cyanide at ppb levels but not nearly as much as peach pits and almonds. I really don't think what he is smelling is cyanide (at least I hope not).

[Thomas Fransson]

Interesting!
Well in best cases it could be some combination of that english ale yeasts sometimes soapy flavour
combined with some other flavour contributors from i.e. hops, in this case Fuggle and EKG.
I've sampled the kegs now again and it looks like it's starting to mellow out.

Thanks for your input and help on this one, i've never experienced something like it before.

Now I guess, if I want to package this beer, a capsule would be more appropriate than a bottle

Cheers!