aeration

[the lizard king]

Just a quick questin I use a diffusion stone for wort aerations. for those of you that do the same, about how long do you let the wort aerate for, I have been about 2 to 3 minutes. I am not sure if there is a norm for this or not, but I dont want to over do it.

[brewranger]

o2 or air?
5 gals?

[ajdelange]

With air it is impossible to overdo but it has been theorized that the protein removed by the foam that forms is subsequently unavailable to form head later on when the beer is finished. With enough O2 flow that tiny bubbles just break the surface (again, you don't want much foam to form) a couple of minutes with a nominal sized stone should do it. And it is important. I've been going nuts trying to get 5 gal of starter going - three failures in a row using 2 packages of yeast. The reason: no O2 making it into the wort (leaking out the back of a broken flow meter).

[brewranger]

unrelated...

ajd you're a "pretty techy guy" what line of business are you in?

[ajdelange]

I am in the "business" of being retired but I was an electrical engineer for 40 years before that.

[SnowGoon99]

Hey AJ - Any documentation behind that "foam" theory? I like to know the correlation between yeast health due to aeration and the loss of head retention due to the same reason.

[ajdelange]

Hey AJ - Any documentation behind that "foam" theory? I like to know the correlation between yeast health due to aeration and the loss of head retention due to the same reason.

Afraid not. I got that years ago from a guy that had gone to Siebel who told me he had learned it there.

Evans and Bamforth (in Beer, A Quality Perspective) do mention "Over foaming of beer during fermentation resulting in loss of foam promoting components..." but they are talking about foam induced by the CO2 produced by the fermentation here. I suppose it could be the same with oxygen. The explanation given at Siebel was that once the protein was removed from the solution to the extent that foam was formed it was no longer available.