too much Oxygenation?

I use pure 02 for oxygen with a stone. I just saw a post where someone claimed that with pure O2 you could saturate your wort with O2 and "suffocate" the yeast.

He was basically trumpeting his aquarium pump oxygenation setup, where you can't over-oxygenate.

Any truth to this? I use a flow meter with my setup, but just want to know the relative truth of his claim.

Cheers!

Excessive oxygen would lead to excessive yeast growth and would effect the flavor of the beer. So yeah you can over do the O2.

Are you having problems with your beer? How much O2 are you using?

Pure O2 for 1 minute in a 5 gallon batch with a SS airstone (.5 or 2 micron) will never overdo it. Simple rule that has worked well for me.

FredTheNuke said:

Pure O2 for 1 minute in a 5 gallon batch with a SS airstone (.5 or 2 micron) will never overdo it. Simple rule that has worked well for me.

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That's what I do and it works well.

Unless the wort was under pressure, I don't see any way you could possibly get enough O2 dissolved in wort to really hurt the yeast. It saturates pretty low and everything else just bubbles up and away. BTW - air "saturates the wort" too - every gas does. Carbonating beer is the act of saturating the beer with CO2.

I have seen numerous blogs where people did side-by-side tests of "over-oxygenating" vs normal levels. They still got beer both ways, but the consensus seems to be that the over-oxygenated had similar flavor but didn't seem to have quite the same mouth-feel. That was with people going way over the top with the O2 and trying to see if they can create a difference.

If I recall correctly, the saturation is at about 10 minutes with typical O2 tank in a typical gravity (1.040 -1.050) and stone similar to what the OP listed. _Yeast_ by Jamil Zainasheff and Chriss White details all of this. Basically the tests done by White Yeast have found a typical air pump will increase the O2, but not much about a good stir/shake of the carboy. To really get the oxygen in, you need pure O2 a good stone and about 8 to 10 minutes.

I generally go 3 minutes with a stone on a wand, but I have a flow meter set to .5 scfh. That's for 5 gallon batch. For 10 gallons I go 6 minutes at the same flow rate.

I was really just wondering about the whole "suffocate the yeast" idea. Seems kind of fishy to me I always thought the worst case scenario was that the wort wouldn't absorb O2, but would just bubble it out, like if you didn't use a stone.

ACbrewer said:

If I recall correctly, the saturation is at about 10 minutes with typical O2 tank in a typical gravity (1.040 -1.050) and stone similar to what the OP listed. _Yeast_ by Jamil Zainasheff and Chriss White details all of this. Basically the tests done by White Yeast have found a typical air pump will increase the O2, but not much about a good stir/shake of the carboy. To really get the oxygen in, you need pure O2 a good stone and about 8 to 10 minutes.

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You don't want to saturate your wort with O2. A few minutes is more than enough.

It's the same concept as fertilizer on your lawn - some is good - too much is not...

FredTheNuke said:

It's the same concept as fertilizer on your lawn - some is good - too much is not...

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Since delivery methods matter, we will need to talk in specifics. Most folks are opening up a tank full blast. I have a flow meter.

I appreciate your comments. But no one is arguing that it's perfectly fine to go nuclear on your wort with O2. But how much is "some" and how much is "too much"?

Anyone out there use a flow meter? This would seem to quantify the O2 somewhat.

Dgonza9 said:

Since delivery methods matter, we will need to talk in specifics. Most folks are opening up a tank full blast. I have a flow meter.

I appreciate your comments. But no one is arguing that it's perfectly fine to go nuclear on your wort with O2. But how much is "some" and how much is "too much"?

Anyone out there use a flow meter? This would seem to quantify the O2 somewhat.

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Actually, most people open the tank only to the point where it starts bubbling (further than that is pretty wasteful).

What kind of tank and regulator do you use?

Excessive oxygenation can lead to a total lack of "character" due to reduced ester production (even beyond what you'd want for a neutral beer), and increased production of higher alcohols/fuels, making it seem "hot" or solventy.

That being said, you have to really overdo it in order to overoxygenate, it's not something you'll manage unless you're going seriously overboard (like the 10 minutes stated above). On the other hand, an aquarium pump - or any other method of aeration, for that matter - can't even *meet* the needs of most yeast strains.

So oxygenation for 1-3 minutes (with the typical homebrew-store setup) is a better option than aeration. Sure, you MIGHT overoxygenate, but it's really not that easy, and at least it has the ability to adequately oxygenate most beers - aeration does not.

For the record, I don't have a flow meter, but I've calibrated my setup with a professional DO meter. Even a flow rate won't tell you much if it was determined with a different air stone, as it results in different DO levels over a given length of time.

emjay said:

On the other hand, an aquarium pump - or any other method of aeration, for that matter - can't even *meet* the needs of most yeast strains.

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People have made beer for thousands of years without pure O2 and plenty still win competitions without it. I would say that the yeasts needs are being met.

bleme said:

People have made beer for thousands of years without pure O2 and plenty still win competitions without it. I would say that the yeasts needs are being met.

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That's both

1) a fallacious argument, and
2) a different (less scientific) definition of the yeast's needs/requirements. There is quite a bit of research indicating that yeast performance and health can benefit from DO levels not achievable with air.

I'm not at all saying good beer can't be brewed without oxygen. But (usually small) improvements can be made in most styles by producing a DO level higher than the saturation point of air, and yeast health can also be improved, which is particularly important if you farm or repitch yeast for several generations. The difference that can be achieved is smaller than almost any other fundamental change that a brewer can make in an effort to produce better beer, and as such I'd actually say that a brewer shouldn't switch to oxygenation if that money could be put towards something else (eg fermentation temp control, a full boil setup, going all- grain, etc).

If you want to stick with aeration, more power to you... be my guest. I was really just addressing his concern that oxygenation might be "worse" than aeration (which it isn't), not trying to proclaim the vast superiority of it. Hell, I even intentionally under-oxygenate some styles where the resulting flavors are actually desired. So please, relax.

The difference is between a yeast's 'needs' and it's 'wants'. The yeast was originally harvested right here on earth. It is designed to grow, reproduce and eat sugar in this atmosphere. We can pump it full of O2 and nutrients. They have tested in labs that they can make stronger yeast that way. The assumption that makes better beer is debatable and matter of taste and opinion.

I don't mean to be nit-picky. You addressed the OP's issue correctly. I was just trying to clarify for any new brewers possibly reading that they can make award winning beer with just 5 minutes of shaking.

bleme said:

The difference is between a yeast's 'needs' and it's 'wants'. The yeast was originally harvested right here on earth. It is designed to grow, reproduce and eat sugar in this atmosphere. We can pump it full of O2 and nutrients. They have tested in labs that they can make stronger yeast that way. The assumption that makes better beer is debatable and matter of taste and opinion.

I don't mean to be nit-picky. You addressed the OP's issue correctly. I was just trying to clarify for any new brewers possibly reading that they can make award winning beer with just 5 minutes of shaking.

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I'd certainly agree with this. As a whole, my brewery is littered with things that I don't absolutely need to make good beer.

I have never used pure 02, just aerate by various methods. All of which I have read are inadequate. Oxygen helps the yeast in the reproductive phase, no? Many dry yeast manufacturers say extra 02 is not necessary because they build the yeast to be pitched straight into wort. Most people using liquid yeast build a starter.

I'm not convinced aeration/oxygenating is as critical as it's made out to be. Pitch the correct amount of yeast and they'll do their job....

Then again, I'm probably just saying this to justify my process and to talk myself out of spending more money on an 02 setup. S

So far my beer attenuates just fine without the oxygen addition, some aeration yes.

It's like playing baseball with or without steroids! Of course you can play without but if you have them you hit a much higher percentage of homeruns (Thanks, Barry)!!!

FredTheNuke said:

It's like playing baseball with or without steroids! Of course you can play without but if you have them you hit a much higher percentage of homeruns (Thanks, Barry)!!!

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That's a good analogy.

And for the LAST ****ING TIME oxygenation/aeration has little to do with attenuation (SOMETIMES you may get a point more, but the difference is generally negligible), so the fact that one's beers seem to ferment out completely means about jack shìt.

I have an oxygen setup but I rarely use for anything other than big beers. 1.060 plus. I do shake it for no less than five minutes. What I draw from Zainasheff and White is that by shaking well for five minutes with a smaller beer I get to the lower end of optimal dissolved oxygen, with no risk whatsoever of overoxygenation.

I do believe that I have tasted the effects of overoxygenation in the form of fusels. It happened with three beers just after I acquired and started using oxygen. I never gave it more than a 2 minute shot, though without benefit of a flowmeter that means little.

Until we're measuring dissolved oxygen, this is an area where we're all pretty much shooting in the dark.

Correct me if I'm wrong, but wouldn't the DO come down if you let the wort sit for a bit? I would think oxygen would come out of solution fairly easily in my uninformed, broad spectrum thinking. I would think that if you supersaturate your wort with oxygen, the DO level would come down, eventually reaching equilibrium with the atmosphere (8 ppm eventually?). How fast this happens, I don't know. This is my thinking at least, as to why it's tough to overoxygenate your wort.

StoneHands said:

Correct me if I'm wrong, but wouldn't the DO come down if you let the wort sit for a bit? I would think oxygen would come out of solution fairly easily in my uninformed, broad spectrum thinking. I would think that if you supersaturate your wort with oxygen, the DO level would come down, eventually reaching equilibrium with the atmosphere (8 ppm eventually?). How fast this happens, I don't know. This is my thinking at least, as to why it's tough to overoxygenate your wort.

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You DON'T supersaturate the wort, so no.

When you boil it, all the oxygen is driven off. The reason an oxygen tank is preferable to air is that with air, you're dissolving other gasses into the wort as well. Air is only about 21% oxygen, meaning the wort gets saturated with all the gasses that make up air before the DO reaches an optimal level. With pure oxygen, you simply don't run into that issue. And unless you start vigorously agitating the wort afterwards, there just isn't enough gas exchange to allow it to move to significantly towards an equilibrium.

emjay said:

You DON'T supersaturate the wort, so no.

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Thanks emjay, I stand corrected. I'd be interested to see what the DO levels in a standard gravity wort would be, from someone with a meter obviously, immediately after infusing with O2, and then at certain intervals over time. I think most people immediately pitch after aerating/oxygenating (rightly so). Sounds like I need to do more reading...

bleme said:

... 5 minutes of shaking.

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My original reason for buying an O2 aerator setup was for better beer. However, after having it for some time, I can highly recommend it just to avoid the shaking. Call me lazy I guess, but it is one of my favorite investments just for not having to pick up my fermenter and shake like crazy.

+1 on that. I love my Williams' O2 wand. I'm stoked to be improving my fermentations, but even more I'm happy to be able to stick a SS tube in my wort for a minute and have that whole aeration step done with...

It's even nicer when you have an online O2 stone on the output of a plate chiller. You literally just open the regulator or valve... and even that I'll probably automate eventually

emjay said:

It's even nicer when you have an online O2 stone on the output of a plate chiller. You literally just open the regulator or valve... and even that I'll probably automate eventually

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I used to do that, but found it was more trouble than it was worth. Mine kept clogging and was not easily removable. Now I go with a wand just for the ease of it. But I know other people do well with injection.

emjay said:

I'm not at all saying good beer can't be brewed without oxygen. But (usually small) improvements can be made in most styles by producing a DO level higher than the saturation point of air, and yeast health can also be improved, which is particularly important if you farm or repitch yeast for several generations.

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This.