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 Home Brew Forums > I completely underestimated role of oxygen
04-23-2011, 08:01 AM   #81
tesilential
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Quote:
 Originally Posted by SpanishCastleAle Any O2 over the saturation level for a given temp would just come out of solution, so you're right that reducing it just to hit a number might seem fruitless because it will come out as you warm it back up.
Let's suppose shaking at 40*f does indeed get you 10ppm of oxygen (I have no idea if it does or not). Why do you think warming up would cause it to leave solution? The wort doesn't care if the O2 came from an oxygen tank or shaking or whatever. If room temp wort can keep 10ppm oxygen dissolved then it doesn't matter how it got there. As long as you don't shake it up, the oxygen should stay dissolved.

Edit: essentially the limiting factor of traditional aeration is the ambient oxygen concentration, not the saturation point of dissolved oxygen in the wort.
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04-23-2011, 09:57 AM   #82
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Quote:
 Originally Posted by tesilential Let's suppose shaking at 40*f does indeed get you 10ppm of oxygen (I have no idea if it does or not). Why do you think warming up would cause it to leave solution? The wort doesn't care if the O2 came from an oxygen tank or shaking or whatever. If room temp wort can keep 10ppm oxygen dissolved then it doesn't matter how it got there. As long as you don't shake it up, the oxygen should stay dissolved. Edit: essentially the limiting factor of traditional aeration is the ambient oxygen concentration, not the saturation point of dissolved oxygen in the wort.
You're very wrong about that. At fermentation temps, 8ppm of dissolved oxygen IS the saturation point of air in beer. That's why all methods using ambient air (whether shaking, using an aquarium pump, or anything else you could possibly conceive of) share the exact same limit. You can even compress the air all you want, but as long as it remains the same proportion of oxygen, it makes absolutely no difference even if you're able to temporarily double the amount of oxygen per cubic inch.

The thing you seem to be overlooking is that 8ppm is simply the amount of oxygen when you dissolve air into the beer, but you are still dissolving all the other gases present in air into the beer. So if you add up all the other gases you dissolve by shaking, it's well over 8ppm, but these gases are unimportant and useless for our purposes to even talk about when comparing dissolved oxygen resulting from different aeration methods, since these other gases are, at best, totally useless to yeast - and in fact, CO2 is even harmful to it.

That's the one and only reason an oxygen tank allows you to dissolve more oxygen. Not because it's compressed or anything, but because it's pure oxygen. The limit of total dissolved gases - whether using an oxygen tank, aquarium pump, or simply shaking vigorously - will be roughly the same. I say roughly because gases do vary in terms of solubility, but the point is that when talking about solubility, solutes are additive - they DO NOT dissolve independent of one another, and DO NOT each reach their own saturation point regardless of the other solutes present within the solvent. An equilibrium forms between the mixture of solutes (in this case, air) and in practical terms, that mixture can kind of be thought of as having its own solubility and saturation points. Interesting to note is that most atmospheric gases of any significance (with the exception of CO2 and argon) are even more soluble in water than oxygen anyways, including nitrogen. The only thing preventing you from dissolving more gas into the wort is indeed that you reach the point of saturation. Raising the temperature lowers the saturation point and WILL cause oxygen (and the other gases) to come out of solution.

According to Henry's Law, there are two ways to increase the saturation point: lower the temperature of the solvent, or increase the pressure of the gas directly above it (essentially what we do to achieve carbonation, and why the CO2 only comes out of solution, forming bubbles, when the bottle is opened.) Fermentation can be done under increased pressure, so it presents some interesting possibilities (though it is known to stress the yeast) but it is a bit absurd to think about using the shake method because, due to the fact that the method totally precludes isolating the air at the top of the fermenter from the rest of the room since that's directly how you're introducing the air. So the only way it's even doable is is to shake it in a high pressure environment - either a pressurized room/chamber, or WAY below sea level. And with a typical homebrew fermenter, you'd have to leave it there, because it would come out of solution in a lower pressure environment by equalizing through the airlock, and sealing the thing would just make it explode with any significant pressure differential - a pressure valve would be useless since typical plastic and glass fermentors can't handle any significant amount of pressure anyways. Perhaps a stainless steel conical built for functioning under pressure would work, but I'm sure by now, anybody reading this would have realized that this is all far more complicated and expensive than just using an oxygen tank. If YOU REALLY want a higher ppm at the cheapest cost possible, you COULD just forget the stone, buy an oxygen tank, purge the fermenter headspace with oxygen, and then vigorously shake it, but if you're going to do that, I find it silly to just stop there, not to mention that it becomes extremely difficult to gauge how much oxygen is being dissolved, and it would be very easy to seriously under-oxygenate the wort (rendering the oxygen pointless) or even significantly over-oxygenate by attempting to compensate and make sure that you're not doing the former. It can be pretty difficult and back-breaking to reach 8ppm with the normal shake method, but due to the difficulty in estimating dissolved oxygen as well as the inherent inconsistency of the method preventing experimentation to settle on a combination of time and intensity that produces the best result (in lieu of knowing the actual oxygen levels), that 8ppm limit is probably, overall, a good thing...

However, if somebody already has a a conical able to withstand decent amounts of pressure, an aquarium pump alone could actually be sufficient, depending on how much pressure the pump itself could handle. As stated before though, shaking still isn't really viable in this situation due to the need to perform it in a high pressure environment, and the cost of doing something like that would be stupidly high.

The implications of Henry's Law for our high-altitude friends is very interesting though. The higher the altitude one lives (and brews) at, the more benefit they could potentially have in investing in an oxygen setup. Since these systems cost the same for everyone, they'd actually be getting more bang for their buck, since when using pure oxygen at sea-level and presumably every livable altitude, you can actually dissolve TOO MUCH oxygen and start negatively affecting the beer (creating off-flavors and harming the yeast) WELL before the saturation point.
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04-23-2011, 01:04 PM   #83
emjay
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Heck, it's not nearly as expensive as I thought to get the equipment necessary to conduct experiments measuring total dissolved oxygen using every possible method/scenario/idea people could come up with.

Of course, I can think of many other things I'd rather put \$300 towards right now. But I'll gladly accept donations

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04-23-2011, 02:38 PM   #84
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Not trying to rock the boat here, but has anyone read this?

http://hw.libsyn.com/p/6/8/b/68bd31b...ionMethods.pdf

It looks like rocking/shaking the carboy achieves faster and more complete oxygen saturation than room air through a stone. They didn't use pure O2 though the stone, but if you can achieve such high O2 saturation through rocking/shaking the carboy (>95% saturation), why bother with the O2 setup?

You guys have all provided anecdotal evidence that the beer is better with an O2 tank and stone, but where's the real evidence?

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04-23-2011, 04:49 PM   #85
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Quote:
 Originally Posted by nfazz Not trying to rock the boat here, but has anyone read this?http://hw.libsyn.com/p/6/8/b/68bd31b...ionMethods.pdf It looks like rocking/shaking the carboy achieves faster and more complete oxygen saturation than room air through a stone. They didn't use pure O2 though the stone, but if you can achieve such high O2 saturation through rocking/shaking the carboy (>95% saturation), why bother with the O2 setup? You guys have all provided anecdotal evidence that the beer is better with an O2 tank and stone, but where's the real evidence?
Don't worry, you're not rocking the boat because there's nothing new about those findings, they happen to be rather obvious to anyone who's aerated with a pump for the recommended 30 minutes, and it has very little to do with the discussion at hand.

The paper deals strictly with sources using ambient air. 95% saturation using air isn't the same thing as 95% saturation using pure oxygen... in fact, it's far, far, less. You are NOT achieving nearly as high a concentration of dissolved oxygen.

As for the real evidence, at least a few sources have been pointed to. Try picking up a few books on the subject. The science is clear and rock-solid, and it's not being disputed. The only argument being made here against oxygenation that has even a remote chance of being legitimate is whether or not the benefits of pure oxygen are worth the \$50 investment, especially if that money could be used towards other brewery improvements.
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04-23-2011, 04:56 PM   #86
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Quote:
 Originally Posted by emjay Don't worry, you're not rocking the boat because there's nothing new about those findings, they happen to be rather obvious to anyone who's aerated with a pump for the recommended 30 minutes, and it has very little to do with the discussion at hand. The paper deals strictly with sources using ambient air. 95% saturation using air isn't the same thing as 95% saturation using pure oxygen... in fact, it's far, far, less. You are NOT achieving nearly as high a concentration of dissolved oxygen. As for the real evidence, at least a few sources have been pointed to. Try picking up a few books on the subject. The science is clear and rock-solid, and it's not being disputed. The only argument being made here against oxygenation that has even a remote chance of being legitimate is whether or not the benefits of pure oxygen are worth the \$50 investment, especially if that money could be used towards other brewery improvements.
I would love to see some of this science. I've read this entire thread and haven't seen anything concrete. Care to enlighten us all?
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04-23-2011, 05:12 PM   #87
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Also, I looked into the probe used in the experiment. It measures the oxygen saturation in solution, not the air saturation. This seems to be the opposite of what you are claiming. Do you really know what you're talking about? If so, please post links to the experimental evidence. If not, perhaps an experiment could be designed to settle the issue once and for all? I might be willing to invest the money in the testing equipment and various aeration methods. I'm just trying to see if anyone has actually done this, before I invest the money. If pure O2 aeration makes a difference, we can all go out and buy the kits. If not, we can save everyone some cash.

Any suggestions for experimental design?

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04-23-2011, 05:30 PM   #88
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nfazz, did you read through this entire post?

There is scientific data presented. You may not buy into it (I'm still on the fence) but it has already been posted.

My go to is Briggs. He seems to suggest that the optimal oxygen level is 10-15 ppm. And you can only achieve 8ppm using room air in any fashion.

I'm not saying 10-15 ppm is necessary in home brewing but its possible. Maybe if you pitch well or over pitch, oxygen is not as important.

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04-23-2011, 05:42 PM   #89
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Quote:
 Originally Posted by nfazz Also, I looked into the probe used in the experiment. It measures the oxygen saturation in solution, not the air saturation. This seems to be the opposite of what you are claiming. Do you really know what you're talking about? If so, please post links to the experimental evidence. If not, perhaps an experiment could be designed to settle the issue once and for all? I might be willing to invest the money in the testing equipment and various aeration methods. I'm just trying to see if anyone has actually done this, before I invest the money. If pure O2 aeration makes a difference, we can all go out and buy the kits. If not, we can save everyone some cash. Any suggestions for experimental design?
Please read more carefully. The probe measures dissolved oxygen content - as in, concentration, not saturation. It cannot possibly measure "saturation". What they did was determine how much dissolved oxygen there was when it WAS 100% saturated with air, and used that to determine how oxygen levels in their tests compared to that. Had they calibrated that 100% set-point by saturating it with pure oxygen, that 95% would probably be closer to 20%.

Not to be unduly rude, but what good does referencing the hard science do when the failure to understand something even as simple as the difference between concentration and saturation makes you conclude pretty much the exact opposite of what something says?
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04-23-2011, 07:50 PM   #90
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Quote:
 Originally Posted by nfazz I would love to see some of this science. I've read this entire thread and haven't seen anything concrete. Care to enlighten us all?
Lets slow down a minute here.

The fact that pure O2 is a really good/better method for aeration is not up for debate any longer. Why, because I'm the OP and I can say whatever I want. Can we agree it is a pretty good method? I think we can. You think shaking things around is just as good - okay. I know I fell into this trap for a few posts too, but maybe we just need to agree to disagree about the science here. Some people think humans rode around on dinosaurs. Who am I to say they didn't? After all, I haven't conducted any experiments to prove my point.

Now that that is out of the way.

First of all, no, I will not be conducting any sort of experiments for comparing a beer with O2 to a beer without O2. I've got a little hunch the beer with the O2 will be better (because I made 24 batches without, and 1 batch with, and the "with" wins - coincidence?). And since I only get to brew about once a month, I am not going to start undercutting my beer quality for the sake of "experiment" to appease some doubting Tom. Buy a kit and see for yourself, or don't. It is not effecting me.

Second, experimentation about dissolved oxygen concentrations has already been done. How can you possibly say you read the entire thread and didn't see anything concrete to that effect? As I am typing this, I am on my couch, and kind of shrugging in disbelief. Even I feel confused. Personally, I quoted and referenced experiments done by Wyeast and White Labs. I offered page numbers and links. But whatever, if that is not enough for you - fine. It is not effecting me.

Finally, I do not have any desire to "convince" anyone who was not already thinking seriously about making this process tweak. The truth is, if you don't want to start doing it, I just don't care. I will never have to drink your beer, so if you are happy with it, then I am happy you are happy. Just brew, shake that carboy up really well, and enjoy. Okay? It is not effecting me.

So in summary, if anyone has been on the fence, and wants to take my "anecdotal" findings at face value - great. I have a feeling you will be happy with your "anecdotally" improved results. For those that responded to my post about finding great improvements with O2 by saying "I disagree!"; that's okay too.

I have no agenda, and I do not want to become the "O2 guy", but for anyone already on the fence, don't let "I disagree!" keep you from making better beer. "I disagree" can stick to what has worked for them for so long now. They obviously know what they are doing, and their beer has no room for improvement. It was ridiculous for me to suggest such a thing.

In fact, I could have been wrong from the start. After all, I have nothing to offer but some anecdotal evidence of one great batch of beer. It was probably dumb luck. And maybe my taste buds aren't even that good. I still haven't drank my beer back to back with some poorly handled Guinness; so how can I compare it? You're right, this whole thread was probably just a waste of everyone's time. So I apologize to anyone who has contributed.

Now excuse me, I have a stout to go choke down.

Joe
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