Over-Oxygenation and Fusels

On April 19, I wrote in to Mr. Wizard of the Brew Your Own magazine, with the following (long-winded) question:

In the May-June 2013 edition of BYO, Jamil Zainasheff discusses the Belgian blond style. At the very end of the article, he discusses “oxygenation” (i.e., with pure O2, as opposed to “aeration” with air) and states that (a) over-oxygenation of wort at pitching can result in fusel production, presumably outside of any other factors or variables; which obviously also suggests THAT (b) over-oxygenation of wort is even possible. Jamil goes on to suggest an oxygenation rate of 1 L/min for one minute.

First, is (b) true? Is over-oxygenation of wort even possible? I’ve read on a number of forums and other places — though, unfortunately, none available to cite at the moment — that speculate that over-oxygenation of the cooled wort (at pitching time) is *not* a reasonable concern. The thought is that the solubility of O2 in the wort is limited, and that any possible over-saturation would likely leave solution within short order.

Second, if (b) should be true, I have never read anything (else) that suggests a link between fusel production and oxygenation. Everything I’ve read suggests fusel production is a result of poor fermentation temperature control. Is there any support for Jamil’s oxygenation claim? Is there any known oxygenation rate (i.e., in contrast to the cited 1 L/min for one minute) that will lead to noticeable fusel production, even with tightly controlled fermentation temperatures?

I ask because I do oxygenate my wort, and have for some time, but my regulator does not have a gauge by which I can measure flow. If this is more than a theoretical issue, I may need to invest in some kind of flow-metered regulator.

Brew Your Own Question to Mr. Wizard

Brew Your Own Question to Mr. Wizard

In the July-August 2013 edition, Mr. Wizard, Ashton Lewis, provides an answer!  Follow the link for the full (also, long-winded) answer.  My take on it is that Jamil needs to “Relax, Don’t Worry, Have a Homebrew.”

If you also follow Basic Brewing Radio, James’ July 4, 2013 episode on aeration clearly identified that, in a blind taste-test, the “over-oxygenated” wort was the group favorite; albeit not a rigorous scientific analysis, it seems to support a healthy RDWHAHB attitude.

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