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Can pure oxygen kill yeast

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pherball

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i pitched a batch of yeast last night, woke up this morning...and nothing was happening. Usually after the same duration in the past i have activity and krausen. Then i remembered that this time i pitched the yeast and then hit it with oxygen from a tank. I am thinking this might be less harmless to the yeast than say the same order would have been if using air as opposed to oxygen. I am thinking about pitching more yeast now if i don't see anything happen by this afternoon.
 

david_42

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I've been assured by the people at Wyeast, that a single oxygenation will not hurt the yeast.
 

malkore

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you need to exceed 20ppm or something of O2 to 'burn' the yeast. that'd be one very very long O2 injection, or lots of small 30 second bursts.

the thing to remember is, when you inject O2, you're giving the yeast a lot of oxygen to grow more yeast, which is 'pre fermentation'. when the O2 is gone, they'll go nuts on sugar.
 
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pherball

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it sounds as if the oxygen would also increase the lag time, since fermentation can only begin once the oxygen has been expended, thus the more oxygen present the longer it will take to deplete before fermentation of sugar. this makes perfect sense to me if that in fact is what is going on.
 

FlyGuy

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Yep -- lots of O2 equals a longer lag, but probably a cleaner fermentation. That's why it always makes me wonder why people are so obsessed with lag times.

And as stated above, apparently the yeast manufacturers now say that it is nearly impossible to over-oxygenate your beer unless you are oxygenating over and over or continuously. There are some crazy myths floating around out there about how easy it is to over-oxygenate and how oxygenation kits are too risky to use. Silly stuff.
 

malkore

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agreed. you'd have to try REALLY hard to over oxygenate a beer even w/ pure oxygen.

also agree about not freaking out over lag times. lag time can leave you susceptible to infection, sure....but if your sanitizing habits are good, you really have nothing to be worrying about.
 
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