Am I retarded when it comes to oxygen?

[PistyPete]

Interesting thread. I'm wondering if anyone has measured DO levels at different time points after oxygenation? I've heard from various sources that some, possibly even most, of the oxygen that you pump in will eventually come back out of solution. Of course, some is taken up by the yeast as well so it's hard to say how much actually gassed off or was taken up...

I also recall listening to an interview with Chris White (I think it was at the NHC in '08) where he recommended 2 minutes of O2 and suggested some benefit might be had from giving a second blast 10-12 hours after pitching (though he wasn't certain of that).

He also stated, I believe, that 10ppm DO was ideal for most beers and that over-oxygenation was NOT a real issue. Has anyone ever experienced any negative effects from "over-oxygenating"?

posting.php?mode=reply&f=19&t=19539#

[Spelt]

Interesting paper on wort aeration.

http://c3.libsyn.com/media/18257/Aerati ... 9fbf860c38

Interesting thing is that this research suggests that rocking and shaking are the most effective method of aeration. How low tech!
See graph at end of study.

[ajdelange]

Interesting thread. I'm wondering if anyone has measured DO levels at different time points after oxygenation? I've heard from various sources that some, possibly even most, of the oxygen that you pump in will eventually come back out of solution.

If you do the math on the data I posted a couple of days ago you will see that the amount of oxygen pumped into the wort amounted to about 90 mg/L and a measurement taken at the completion of filling showed about 20 mg/L. Conclusion: 0.5 LPM is way too much for a 2 gpm wort flow. It should be obvious that if you see O2 bubbles breaking the surface you are losing O2 to the air (my fermenter is closed so I can't see this). Also, yeast begin consuming O2 immediately. Since filling my fermenter takes half an hour, the first yeast in have had that long to consume oxygen so that the total dissolved was doubtless appreciably more that 20 mg/L. As I recall the 20 mg/L reading at the completion of filling dropped to about 17 mg/L an hour or so later.