Did I just oxidize my beer?

I brewed a 1.052 American brown ale and pitched some WY1056 slurry that was 4 weeks old. It was about 24 hours later and not a sign of fermentation so about 3 hours later I gave it a 15 second shot of pure O2 for a second oxygenation. I noticed when I did it, there was a slight krausen starting to form...just barely. So about 1 hour after the O2 shot, it's going gangbusters and bubbling away. Did I just oxidize my beer because it seems that it was likely to have been going anyway without the O2? Or will the yeast take care of it since it was so early in the fermentation. I'm such an idiot! I should have left it alone.

It was already fermenting when you hit it with your O2, it just hadn't starting showing the more easily visible signs at the time. How was the slurry treated? You says 4 weeks old...was it washed yeast from a prior batch? Did you pitch it into a starter first? How was it stored? It sounds like you used some old-ish, dormant yeast that just took a while to get going. In the future, give yeast that age a starter to wake it up and strengthen it before pitching it into a beer.

U should be fine, the CO2 and yeast reproduction from fermentation will remove any excess O2.

You should be fine, from what I understand as long as you don't introduce O2 after about 36 hours you are probably good.

Thanks for the reassurance...next time I'll leave well enough alone!!

+1....as long as there was still active fermentation left to go after you hit it with the O2 shot, the yeast will use most of that O2 and their CO2 off-gassing will push the rest of the O2 out of the beer.

The oxygen really needs to be dissolved in the beer for a few weeks for it to start changing the character of the beer. The O2 you shot into the beer is mostly gone by now.

You're good!

Oxidation shouldn't be a problem, but be aware that adding oxygen after fermentation begins produces a lot of diacetyl. (The yeast produce and excrete the precursor to diacetyl (alpha acetolactatic acid) into the wort. If oxygen is present, the precursor is oxidized to diacetyl.) Fortunately, 1056 is a strong diacetyl reducer and should take care of any excess diacetyl by the time fermentation is finished.
Give your airlock a sniff and see if you can smell any butterscotch aroma.

Chris Colby
Editor
beerandwinejournal.com

VikingChrisColby said:

Oxidation shouldn't be a problem, but be aware that adding oxygen after fermentation begins produces a lot of diacetyl. (The yeast produce and excrete the precursor to diacetyl (alpha acetolactatic acid) into the wort. If oxygen is present, the precursor is oxidized to diacetyl.) Fortunately, 1056 is a strong diacetyl reducer and should take care of any excess diacetyl by the time fermentation is finished.
Give your airlock a sniff and see if you can smell any butterscotch aroma.

Chris Colby
Editor
beerandwinejournal.com

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Enjoyed your columns Chris.