Over-oxygenating... what's the damage?

[JayShaw91]

I'm moving the discussion that was going on here http://www.realbeer.com/discussions/showthread.php?p=214990#post214990 to a new thread cuzz nobody likes thread hijacking :D

This dude has a blog and has done some interesting work on the issues of over-oxygenation, plus the easiest way to properly oxygenate your chilled wort for pitching. Linky: http://blog.flaminio.net/blogs/index.php/beer/oxygen/

Obvously, we know you need to oxygenate your wort and that shaking/spraying doesn't really give you the optimal amount of O2. You should use an air stone, O2 tank, whatever.

So now to the point of this thread. What "bad" happens when you over-oxygenate your wort? Off flavors? Premature damage to your brews?

Educate us, Oh Wise Ones!

[Mill Rat]

I've never been too concerned about over-oxygenation. Most homebrewers (me too) underpitch, so all yeast growth is good. Also, once fermentation starts, the CO2 generation will rapidly strip out any O2 that remains. As for all that stirring stuff, I'd rather not be shoving more equipment into my fresh wort that creates additional opportunities for contamination. A fine, gentle stream of O2 bubbles (he is correct about a gentle stream of tiny bubbles oxygenating better that a vigorous stream of large bubbles) will cause enough agitation.

[JayShaw91]

So are you saying that if you underpitch your yeast that over-oxygenating won't hurt as badly?

Also, how 'bout some comments on my air stone use? I usually let it go for 25-30 minutes. Now, in case you're asking about yeast, if time permits I'll grab a Wyeast Activator (the biggie, not the one you build a starter from), smack it, let it plump, and build a starter out of that for 24 hours. Otherwise, I just pitch the yeast after the smack pack looks good seeing Wyeast says that's ready to pitch for most normal beers.

[corkybstewart]

I use pure O2 on my big beers-about 2 minutes of trickle into my conical thru the racking port. The only drawback I've run across is the amazingly violent fermentation I get. I have to wrap the conical in wet towels to keep it from getting to too hot.

[dagomike]

So are you saying that if you underpitch your yeast that over-oxygenating won't hurt as badly?

Also, how 'bout some comments on my air stone use? I usually let it go for 25-30 minutes. Now, in case you're asking about yeast, if time permits I'll grab a Wyeast Activator (the biggie, not the one you build a starter from), smack it, let it plump, and build a starter out of that for 24 hours. Otherwise, I just pitch the yeast after the smack pack looks good seeing Wyeast says that's ready to pitch for most normal beers.

Oxygen is never a good substitute for pitching enough yeast.

One disadvantage to over oxygenating by large amounts is you're getting excess growth. Excess growth will mean less alcohol, but also may have flavor consequences. As with anything in brewing, too little isn't good, but so neither is too much.

The activator is just that -- it activates the yeast. You're getting little to no propagation from that. Smacking the pack should give you good viable yeast ready to go, but may not give as much yeast as you need for a good ferment. The pitching rate is up to you, but I generally like the 0.75 million cells/ml/P on my ales.