I knew Aeration Equipment is a Waste of $...

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RushN24

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I read this study a while back and thought it might be interesting to share it here with HBT. This is not my work at all and I take no credit for anthing other than posting it here for you fine brewers to read.It is just something I found interesting when doing some research. Check it out and see what you think.

My opinion: Seems logical enough, however as much as I would like to agree with the study universally, I feel as though shaking a carboy to aerate becomes in practical with a 10+ gallon batch. thus the study will be most important to the home brewer.

http://c3.libsyn.com/media/18257/Ae...36&nva=20100329011636&t=0cfe8e3f8999a35e2aa0d

Fred L. Johnson, Cheddington Brewery, Apex, North Carolina, USA
 

Grizzlybrew

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I read this a while back and was pleasantly surprised to see the results - and glad I hadn't invested in yet another piece of equipment that I can still make great beer without.
 

TheFlyingBeer

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Good call. Looking into ways to increase the potential of my beer while minimizing my costs. Thinking fermentation temp control is still my next step.
 

remilard

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The chart at the bottom is a little misleading as the y-axis is labelled percent 02 saturation. It is, in fact, percent air saturation and higher 02 levels are possible with direct 02 infusion. This only really matters if you want more than 8 ppm oxygen (and some yeast do better with more).
 

ajwillys

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I know nothing about the study but I've lived in Apex, North Carolina for 26 years and have never heard of Cheddington Brewery. Granted, I was under 21 for many of those years...

EDIT: I don't use aeration really either. Just run it through a strainer on the way out of the kettle. Sometimes (for a big beer), I'll do some extra shaking.
 

Beernik

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The chart at the bottom is a little misleading as the y-axis is labelled percent 02 saturation. It is, in fact, percent air saturation and higher 02 levels are possible with direct 02 infusion. This only really matters if you want more than 8 ppm oxygen (and some yeast do better with more).

I disagree. They used a probe to measure the DO. The probe was calibrated by dissolving air in water.

But you are right, you might be able to supersaturate the wort by using pure O2 when compared to pumping air.
 

GilaMinumBeer

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The discussion is meaningless because the experiment is based on wort aeration and they used clean water instead.

Show me a "discussion" using an actual wort and then I'll listen.
 

Beernik

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Really? I thought wort was 90% water.

Meaningless is hardly the word I'd use. Sure the maximum saturation of O2 is wort vs. The maximum saturation of O2 in pure water are probably not exactly the same.

But the rate at which wort and pure water absorb O2 should be negligible because they are 90% identical. And that is what the graph shows, the rate at which it achieves 100% saturation, not what the maximum saturation is.
 

Bobby_M

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Wow, this article is popping up in a new thread about every 3 days here. It would have been a decent experiment if the guy made sure to boil off all the oxygen first AND used wort instead of water. There were just too many departures from reality to take it 100% seriously.

If you don't want to drop money on O2, it sure sounds "sciency" enough to justify it.
 

babalu87

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Really? I thought wort was 90% water.

Meaningless is hardly the word I'd use. Sure the maximum saturation of O2 is wort vs. The maximum saturation of O2 in pure water are probably not exactly the same.

But the rate at which wort and pure water absorb O2 should be negligible because they are 90% identical. And that is what the graph shows, the rate at which it achieves 100% saturation, not what the maximum saturation is.


OK
How does ABSOLUTELY meaningless grab you?

Your body is 60% water
Can I bring you to a boil and expect your composition to remain as it was pre-boil?

Try this
Brew a big beer , split it into two fermenters.
Ferment one with no aeration and a pack of US-05
Ferment the other with proper aeration and a pack of US-05
 

weirdboy

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OK
How does ABSOLUTELY meaningless grab you?

Your body is 60% water
Can I bring you to a boil and expect your composition to remain as it was pre-boil?

Try this
Brew a big beer , split it into two fermenters.
Ferment one with no aeration and a pack of US-05
Ferment the other with proper aeration and a pack of US-05

Besides the fact that you don't need to aerate the US-05, and that it isn't going to tell you in any meaningful way the % dissolved oxygen in the wort, that's not even testing the same thing as the article, which is different methods of aeration.


Talk about meaningless.
 

weirdboy

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My example isnt testing anything but finished beer and in the end that is the only thing that really matters.

Your example isn't testing anything at all. It literally does nothing to test the efficacy of different methods of aeration.
 

brettg20

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I purposely rack my wort into the primary to oxygenate. The splashing of the wort from my the racking tube hitting the carboy and the wort as it fills the carboy supplies plenty of oxygen and best of all, it's free!
 

wildwest450

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You dont need to aerate wort when using US-05?
You've got to be kidding me right?
I wonder if some of you even brew sometimes.

Not only do I brew but I also know my facts before shooting my mouth off.

And I quote

I always aerate my wort when using liquid yeast. Do I need to aerate the wort before pitching dry yeast?



No, there is no need to aerate the wort but it does not harm the yeast either. During its aerobic production, dry yeast accumulates sufficient amounts of unsaturated fatty acids and sterols to produce enough biomass in the first stage of fermentation. The only reason to aerate the wort when using wet yeast is to provide the yeast with oxygen so that it can produce sterols and unsaturated fatty acids which are important parts of the cell membrane and therefore essential for biomass production.




I have NEVER aerated the wort before pitching any kind of dry ale yeast, which I use 80% of the time. I get full attenuation on all batches.
 

babalu87

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Not only do I brew but I also know my facts before shooting my mouth off.

And I quote

I always aerate my wort when using liquid yeast. Do I need to aerate the wort before pitching dry yeast?



No, there is no need to aerate the wort but it does not harm the yeast either. During its aerobic production, dry yeast accumulates sufficient amounts of unsaturated fatty acids and sterols to produce enough biomass in the first stage of fermentation. The only reason to aerate the wort when using wet yeast is to provide the yeast with oxygen so that it can produce sterols and unsaturated fatty acids which are important parts of the cell membrane and therefore essential for biomass production.




I have NEVER aerated the wort before pitching any kind of dry ale yeast, which I use 80% of the time. I get full attenuation on all batches.

All you have established is that Danstar believes aeration isnt required IF the yeast it rehydrated properly.

Fermentis has a different opinion as do many homebrewers.

Attenuation isnt the only aspect of brewing that makes good beer.
 

wildwest450

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All you have established is that Danstar believes aeration isnt required IF the yeast it rehydrated properly.

I'll take their word on that. I do know what it takes to make good beer. I have had excellent reviews of a beer (by knowledgeable hbt members) made with dry yeast and no aeration. It was no better than any of my other beers made the exact same way.
 

samc

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Here is the actual information Fermentis presented - (love those cut & paste jobs to mis-prove a point)

Re-hydrate the dry yeast into yeast cream in a stirred vessel prior to pitching. Sprinkle the dry yeast in 10 times its own weight of sterile water or wort at 27C ± 3C (80F ± 6F). Once the expected weight of dry yeast is reconstituted into cream by this method (this takes about 15 to 30 minutes), maintain a gentle stirring for another 30 minutes. Then pitch the resultant cream
into the fermentation vessel.

Alternatively, pitch dry yeast directly in the fermentation vessel providing the temperature of the wort is above 20C (68F). Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes and then mix the wort e.g. using aeration.

I can discern no difference when aerating vs. rehydrated pitching of dry yeast (05 specifically). My aeration equipment is no longer used with dry yeast.
 

babalu87

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Here is the actual information Fermentis presented - (love those cut & paste jobs to mis-prove a point)

Re-hydrate the dry yeast into yeast cream in a stirred vessel prior to pitching. Sprinkle the dry yeast in 10 times its own weight of sterile water or wort at 27C ± 3C (80F ± 6F). Once the expected weight of dry yeast is reconstituted into cream by this method (this takes about 15 to 30 minutes), maintain a gentle stirring for another 30 minutes. Then pitch the resultant cream
into the fermentation vessel.

Alternatively, pitch dry yeast directly in the fermentation vessel providing the temperature of the wort is above 20C (68F). Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes and then mix the wort e.g. using aeration.

I can discern no difference when aerating vs. rehydrated pitching of dry yeast (05 specifically). My aeration equipment is no longer used with dry yeast.

What was "misproved"?

Aerating and sprinkling = easier than rehydrating
 

Beernik

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OK
How does ABSOLUTELY meaningless grab you?

Your body is 60% water
Can I bring you to a boil and expect your composition to remain as it was pre-boil?

"Absolutely meaningless" grabs me a lot like someone who didn't spend much time in chemistry class.

Pour a cup of salt in a gallon of water. Get it dissolved. Bring it to a boil. Boil off all the water. And what you are left with is a cup of salt. Pour another gallon of water in it and you can start it all over again.

Sure, wort has sugar instead of water. But you won't caramelize a significant amount of sugar during the boiling process. What % of different sugars you have in your wort depends more on your mash than your length of boil.

The total dissolved solids you have at the beginning of your wort boil is essentially the same that you have at the end of your wort boil (with the exception of hop acids that you add along the way). All the boil does is reduce the volume of water and the amount of dissolved gases. You reintroduce those gases back into the wort by "aeration". After aeration, the only significant differences are the hop acids and the quantity of water.

Back to your example: if you broke me down to my chemical constituents and boiled me. Sure, I would volatilize a bit. The quantity of water would be reduced. Some chemical reactions might take place. But after reaerating my remains, on an elemental level, I would essentially be the same with the exception of some water loss.
 
OP
OP
RushN24

RushN24

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So uh, back to the topic here...the whole point is whether or not, based on this study or other studies you've read or conducted yourself or whatever, do you guys think aeration equipment is really worth the investment. The study, like I mentioned in my OP, seems to be more appropriate for the small scale home brewer.

There are definitely some loose ends in the study as some of you have already poked holes in the fact that the study uses water, among other small details. That is why I posted it here to get a discussion going about whether or not this study is practical, and whether the home brewer should draw any conclusion from it or if you can find some reason to rebuke the conclusion the article draws...etc. It's not really about the efficacy of aeration, no doubt aeration is a necessary step otherwise we wouldn't be discussing it at all, but more so the efficacy of different aeration methods.

If you choose to aerate your wort or not aerate, or aerate when using dry yeast or not that's great. What is of more interest here to me and I'm sure others is, do you agree with the article, do you use aeration equipment, and if so do you believe it is more effective and what would lead you to conclude it is more or less effective than shaking the carboy?
 

babalu87

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"Absolutely meaningless" grabs me a lot like someone who didn't spend much time in chemistry class.

Pour a cup of salt in a gallon of water. Get it dissolved. Bring it to a boil. Boil off all the water. And what you are left with is a cup of salt. Pour another gallon of water in it and you can start it all over again.

Sure, wort has sugar instead of water. But you won't caramelize a significant amount of sugar during the boiling process. What % of different sugars you have in your wort depends more on your mash than your length of boil.

The total dissolved solids you have at the beginning of your wort boil is essentially the same that you have at the end of your wort boil (with the exception of hop acids that you add along the way). All the boil does is reduce the volume of water and the amount of dissolved gases. You reintroduce those gases back into the wort by "aeration". After aeration, the only significant differences are the hop acids and the quantity of water.

Back to your example: if you broke me down to my chemical constituents and boiled me. Sure, I would volatilize a bit. The quantity of water would be reduced. Some chemical reactions might take place. But after reaerating my remains, on an elemental level, I would essentially be the same with the exception of some water loss.

As to the salt experiment, salt as well as the sugars in the wort both increase the boiling point of the "water" (water in "X" because we really arent talking about water any longer)

The experiment used only water , it really has no application RE brewing.

As to your salt experiment, sure if you are using chemically pure salt you might end up with a pound of salt should you boil all the water away had you started with a pound
BUT
We all know many other compounds are both created AND driven off by the boiling of wort.


What you said is this:




You're losing this battle. Just let it go.

Losing the battle is stating that wort doesnt need to be aerated.
 

Edcculus

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If you choose to aerate your wort or not aerate, or aerate when using dry yeast or not that's great. What is of more interest here to me and I'm sure others is, do you agree with the article, do you use aeration equipment, and if so do you believe it is more effective and what would lead you to conclude it is more or less effective than shaking the carboy?

I don't really believe the article. My evidence is purely anecdotal, but I've experienced healthier more complete fermentations since I started using a stone and pure 02. I've seen similar studies where the person figures out that by shaking, you can only get x amound of oxygen into the wort (sorry, dont' know the exact number). That number however is less than the published amount of dissolved oxygen for healthy yeast growth. I think the air is only 21% oxygen anyways, so shaking is really pretty inefficient. An aeration stone and oxygen regulator is only $30 and saves me 10 minutes in my brew day. I also ferment more in buckets than carboys. When shaking a bucket, I invariably spill some wort. Add another 10 min for mopping the floor and a sore back.
 

Bobby_M

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It would be awesome if the chest pounding would give way to a little more friendly conversation given how many variables there are. Here's my summary opinion on this.

If 8ppm is enough O2 to build a big and healthy colony for the task at hand (OG of your batch matters), then the study shows that shaking a carboy can probably get you there.

I don't have 100% confidence in the "within 5 minutes of shaking" part for these reasons: He didn't boil enough O2 out of the sample water. It was noted that 55% saturation was measured before they did anything. Would you conclude that O2 was already on its way to naturally dissolving into the water or the "several minutes" of boiling wasn't enough to get it all out. How much O2 stays in a liquid that's been boiled for a hour anyway?

Assuming 0ppm after a real boil, it would probably take twice as long to reach 8ppm by shaking and I have doubts that the headspace contains enough O2 to go from 0 to 8ppm without flushing the headspace with new air. What else is in that new incoming air? Lacto from your grain crushing? I don't know.

I've experimented with O2 with dry yeast and I can say for now that O2 still affects the yeast colony size. Whether you need more yeast than what comes in the pack is based on OG so there will be hundreds of anecdotal "never had a problem" statements out there. Even if Mrmalty calls for 16g of rehydrated dry yeast, many will pitch an 11g pack and call it a day.

So, back to the original question. Is O2 gear worth it? Even if shaking were enough in all case, I'd rather crack a valve for 30-60 seconds, take a sip of beer, then tuck the fermenter away than to risk spilling my wort while shaking for 5-10 minutes. Other methods that work, including powered stirring with a drill paddle are less labor intensive but equally questionable from a contamination perspective.

If I had a DO meter, I'd repeat the guy's experiment.
 

SpanishCastleAle

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Bobby_M, you aerate with O2/stone; do you use both dry/liquid yeast? The reason I ask is because I just put the wort in the carboy (intentionally creating a lot of agitation) and shake the carboy. I think most of my aeration occurs just getting wort into the carboy. So regardless of whether I use dry/liquid yeast, I think the amount of DO is about the same.

BUT...the yeast cake from similar worts when using dry yeast always seems significantly bigger than when using liquid in my brews (just eyeballing it). Is that the case in your brews? Anybody else notice this? IIRC, in most cases the major 'constraint' to final cell mass is O2 (and/or associated 'nutrients' from it). If this is all true, then could it be a sign that one is not really getting proper DO levels for liquid yeast? Or is it that perhaps the dry yeast is actually over-multiplying because it already has all the nutrients it needs...and then we add O2 on top of that?

The difference in yeast cake size between dry/liquid just seems like it's screaming to me that in at least one case, I'm not pitching the right amount or not aerating properly. And I always try to pitch the right amount.

RE: that experiment; I don't really trust anything quantitative from it but I think qualitatively it at least had something to offer.
 

springer

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I agree with you Bobby that pure o2 is the best way to oxygenate your wort . But the article isn't about oxygenating its about aeration with room air. I believe that between an air pump and shaking they are just about the same as the air around us only has so much o2 in it.The study if you want to call it that is flawed .
 

Bobby_M

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Springer, I'm pretty sure 8ppm is the best you can do on ambient air because that's the equilibrium of the partial pressure of O2. Assuming you replenish the headspace with fresh air as necessary, shaking would be faster than an air pump because it creates many more bubbles at one time and increases the wort to air surface area. I think the study concluded that shaking is faster than pumped air and I agree with that basic conclusion as long as the headspace air is replenished once or twice. This doesn't need to be done with pumped air.

I always see people talking about how well their aeration technique works "because they got a nice frothy head" on the wort in the carboy. Bubbles sitting on top of the wort says absolutely nothing about how much O2 may have been dissolved.
 

Bobby_M

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Bobby_M, you aerate with O2/stone; do you use both dry/liquid yeast? The reason I ask is because I just put the wort in the carboy (intentionally creating a lot of agitation) and shake the carboy. I think most of my aeration occurs just getting wort into the carboy. So regardless of whether I use dry/liquid yeast, I think the amount of DO is about the same.

BUT...the yeast cake from similar worts when using dry yeast always seems significantly bigger than when using liquid in my brews (just eyeballing it). Is that the case in your brews? Anybody else notice this? IIRC, in most cases the major 'constraint' to final cell mass is O2 (and/or associated 'nutrients' from it). If this is all true, then could it be a sign that one is not really getting proper DO levels for liquid yeast? Or is it that perhaps the dry yeast is actually over-multiplying because it already has all the nutrients it needs...and then we add O2 on top of that?

The difference in yeast cake size between dry/liquid just seems like it's screaming to me that in at least one case, I'm not pitching the right amount or not aerating properly. And I always try to pitch the right amount.

RE: that experiment; I don't really trust anything quantitative from it but I think qualitatively it at least had something to offer.

I think it's difficult to use yeast cake appearance as a real indicator of the actual cell count because it can be affected by all the other break material and hop trub. It may also be the case that dry yeast is already such a large colony compared to liquid and of course the latter is affected by whether you make a starter, step it up, age of the yeast, etc. Many brewers try getting away with just pitching a vial/smack pack and in those cases, I'd be much more prone to recommending getting the O2 over the ambient saturation of 8ppm because you're basically making a big starter and fermenting a batch of beer at the same time.

Since you asked what I do;

If my wort is an ale at 1.060 or less, I run O2 into the wort for 60 seconds @ .25 lpm. If it's a dry yeast, I just pitch it dry. If it's liquid yeast, I make a 1 liter starter.

If the ale wort is over 1.060, I still O2 the same way but dry yeast gets rehydrated first or I'll make a 2 liter starter with liquid.

If it's a lager, O2 the same but I step the starter up 1 liter, cold crash and decant, 2 liter, cold crash, decant and pitch only the slurry.
 

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I may be a pretty big guy but there is no way in hell I am shaking 10 gallons of beer:D . I just use the o2 when I pitch liquid and always use a starter . With dry I do let it aerate by letting it run into the carboy from above the neck it does aerate to an extent also carrying the carboy from the garage to the basement it sloshes around quite a bit I also always rehydrate the dry yeast I don't pitch it dry. I like to see the yeast bloom before I pitch, got into that habit when the Notty was questionable
 

Bobby_M

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I hear you. I hate CARRYING a carboy, nevermind shaking it.

Something else I thought of was that you could flood the headspace with pure O2 and shake the carboy to have it done in 5 seconds, but now that's getting ridiculous.
 

springer

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I only carry when i split the batch all other times I use either a sanke keg or a 15 gallon Dulex container and a hand truck.
 

SpanishCastleAle

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I think it's difficult to use yeast cake appearance as a real indicator of the actual cell count because it can be affected by all the other break material and hop trub. It may also be the case that dry yeast is already such a large colony compared to liquid and of course the latter is affected by whether you make a starter, step it up, age of the yeast, etc. Many brewers try getting away with just pitching a vial/smack pack and in those cases, I'd be much more prone to recommending getting the O2 over the ambient saturation of 8ppm because you're basically making a big starter and fermenting a batch of beer at the same time.
Yea, it's just eyeballing it but these are fairly similar worts. And the assumption was 'proper pitching rates' (per Mr Malty anyway). I never even noticed it until I washed some dry yeast and the difference was pretty noticeable, this after washing liquid yeast many, many times.

I'll soon be trying 10 gal batches split into two carboys and will expect to often be using dry yeast in one. Maybe I can test it further.
 

2-0turbo

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You know, this has bothered me since I got into brewing. Those of you who say that the study is flawed, I'm not sure what you believe. The guys checks oxygen saturation with a meter and many of you are saying that "you get more O2 dissolved with your setups." Which, I don't believe.

You guys ever seen water treatment plants where they are spraying the waste water up into the air? Any ideas on why they're doing that? To oxygenate the waste and let the aerobic bacteria do their job. If blowing oxygen through the waste or blowing air was more effective, why wouldn't they do that? Because pure oxygen (O2) is not soluble in water, which is why I've been so skeptical about "bubbling" oxygen through your wort. You not putting any O2 into solution in the wort unless it is only from turning over the fluid and exposing it to more air.

The reason that O2 won't dissolve in water is because it is non-polar and water is polar. Please understand that I'm not saying oxygen is not soluble in water. Pure oxygen never hangs out as just "O", it always pairs up and hangs out with other Oxygen molecules. Consequently, it is O2. But, in air (which is a mixture of many gases, chiefly nitrogen), you can get some free 'O' molecules. Which is why you do get some dissolved oxygen in water--but it because it is in a mixture of air (mostly nitrogen).

Conversely, CO2, which we all know as carbonating gas, is non-polar. It is very soluble in water. When you crank the pressure on your corney, you can HEAR the gas rushing into and going into solution. Want 5 volumes of CO2 in your beer? Crank up the pressure. If you tried the same experiment with pure oxygen, you would get nothing.

It has been a long time since college chemistry, so I might have a couple details wrong here. See this link to play around and see how some molecules are polar and some are non-polar. You can also google a ton of things (molecules) and figure out if they're polar or non-polar. Just one last example to "prove" to you this works. Say you have some rust stains on your bathtub. Rust is Iron oxide, FeO2. I can tell you what would remove the stains without ever trying because you know that FeO2 is polar. Will methanol remove rust stains? No. Because iron oxide and alcohols are both polar. (in fact, all alcohols are polar, so you don't need to try any others) What about carbon tetrachloride? Absolutely. If you have some carbon tetrachloride (which is non-polar), it will easily remove rust stains because Iron Oxide is soluble in Carbon tetrachloride.

This is a complicated topic, but rest assured, pure oxygen is not soluble in water (or wort). If you don't believe me, put some wort into a corny and put 30 psi of O2 on it. You won't see any flow (or very, very little). You're better off pouring your wort between two containers and doing a lot of splashing. Happy brewing guys.
 

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So every pro brewery on earth that injects O2 inline post chiller is wasting money.

Wyeast tested yeast growth for various O2 saturation levels:

DO ppm # Doublings
2ppm 1.2
9ppm 1.5
15ppm 1.62
21 ppm 1.66
26 ppm 1.70

If you can't get O2 to supersaturate in wort, how did they measure up to 26ppm?


Method DO ppm Time
Syphon Spray 4 ppm 0 sec.
Splashing & Shaking 8 ppm 40 sec.
Aquarium Pump w/ stone 8 ppm 5 min
Pure Oxygen w/ stone 0-26ppm 60 sec
 

Synovia

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So every pro brewery on earth that injects O2 inline post chiller is wasting money.

It wouldn't be the first time big business was wasting tons of money simply because that's the way its always been done.

Suggesting that it must be helpful because they wouldn't do it otherwise is just an appeal to authority.
 

BioBeing

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You know, this has bothered me since I got into brewing. Those of you who say that the study is flawed, I'm not sure what you believe. The guys checks oxygen saturation with a meter and many of you are saying that "you get more O2 dissolved with your setups." Which, I don't believe.

They measure saturation as the percent of the maximum that you get by shaking water in air. This is their 100% point. Which works out to be about 8 ppm. By using pure oxygen gas you can up to 26 ppm in the liquid. That would be equivalent to 325% saturation on their scale. If you want rapid growth of healthy yeast, ~ 21 ppm is what you want to shoot for (according to wyeast; style dependent).

You just can't get 21 ppm oxygen in wort by shaking alone.

You guys ever seen water treatment plants where they are spraying the waste water up into the air? Any ideas on why they're doing that? To oxygenate the waste and let the aerobic bacteria do their job. If blowing oxygen through the waste or blowing air was more effective, why wouldn't they do that?

Because, maybe, in that case, the level of aeration they get is sufficient? It is cheaper, easier and safer to just spray the liquid rather than to need pure O2.

Because pure oxygen (O2) is not soluble in water, which is why I've been so skeptical about "bubbling" oxygen through your wort. You not putting any O2 into solution in the wort unless it is only from turning over the fluid and exposing it to more air.

Which is why we use a .2 micron stone to make tiny bubbles. Increased surface area means more efficient transfer.

And O2 is not very soluble in water. It is not completely insoluble (or fish wouldn't live).

The reason that O2 won't dissolve in water is because it is non-polar and water is polar. Please understand that I'm not saying oxygen is not soluble in water. Pure oxygen never hangs out as just "O", it always pairs up and hangs out with other Oxygen molecules. Consequently, it is O2. But, in air (which is a mixture of many gases, chiefly nitrogen), you can get some free 'O' molecules. Which is why you do get some dissolved oxygen in water--but it because it is in a mixture of air (mostly nitrogen).

We are talking O2 here, not oxygen ions or radicals. And it has nothing to do with air being a mixture (except that nitrogen will actually displace oxygen from solution - we use this for de-oxygenating solutions in the lab sometimes).

Conversely, CO2, which we all know as carbonating gas, is non-polar. It is very soluble in water. When you crank the pressure on your corney, you can HEAR the gas rushing into and going into solution. Want 5 volumes of CO2 in your beer? Crank up the pressure. If you tried the same experiment with pure oxygen, you would get nothing.

It has been a long time since college chemistry, so I might have a couple details wrong here. See this link to play around and see how some molecules are polar and some are non-polar. You can also google a ton of things (molecules) and figure out if they're polar or non-polar. Just one last example to "prove" to you this works. Say you have some rust stains on your bathtub. Rust is Iron oxide, FeO2. I can tell you what would remove the stains without ever trying because you know that FeO2 is polar. Will methanol remove rust stains? No. Because iron oxide and alcohols are both polar. (in fact, all alcohols are polar, so you don't need to try any others) What about carbon tetrachloride? Absolutely. If you have some carbon tetrachloride (which is non-polar), it will easily remove rust stains because Iron Oxide is soluble in Carbon tetrachloride.

This is a complicated topic, but rest assured, pure oxygen is not soluble in water (or wort). If you don't believe me, put some wort into a corny and put 30 psi of O2 on it. You won't see any flow (or very, very little). You're better off pouring your wort between two containers and doing a lot of splashing. Happy brewing guys.

So, if oxygen is not soluble in water, when I pump pure oxygen from a cylinder into my fermentors at work (with a water-based medium in them similar to wort), and I see the partial pressure of dissolved oxygen (dO) increasing, what am I measuring? My bacteria - which need oxygen for optimal growth - grow just fine, which they wouldn't do in an anaerobic medium. Please note: I see this with molecular oxygen gas (O2). As an aside, if I use air instead, the dO does not get as high, and my bacteria do not grow so fast. Why would that be?
 

2-0turbo

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They measure saturation as the percent of the maximum that you get by shaking water in air. This is their 100% point. Which works out to be about 8 ppm. By using pure oxygen gas you can up to 26 ppm in the liquid. That would be equivalent to 325% saturation on their scale. If you want rapid growth of healthy yeast, ~ 21 ppm is what you want to shoot for (according to wyeast; style dependent).

You just can't get 21 ppm oxygen in wort by shaking alone.

Okay, maybe not. I honestly can't measure the level of dissolved O2 in my wort and I don't know how many PPM it is. It is not obvious to me that they are using 8 PPM as "100%". If you reread the original abstract, he didn't say that it was adjusted to be the percentage of each method. It was expressed as saturation only, which would imply some upper limit of saturation.

Because, maybe, in that case, the level of aeration they get is sufficient? It is cheaper, easier and safer to just spray the liquid rather than to need pure O2.

Or perhaps it isn't soluble.

Which is why we use a .2 micron stone to make tiny bubbles. Increased surface area means more efficient transfer.

It's a molecular issue, not a bubble size issue. I argue that a stone will only affect the rate of solubility, not the total solubility or the solubility/non-solubility of different gases. Splitting argon (or Oxygen for that matter) into 0.000001 micron bubbles still won't make it soluble.

And O2 is not very soluble in water. It is not completely insoluble (or fish wouldn't live).

True, but fish need like 6 PPM to live. And I didn't say that Oxygen wasn't soluble in water. I'm saying that pure O2, diatomic oxygen is insoluble in water--which is what comes in one of those red bottles.

We are talking O2 here, not oxygen ions or radicals. And it has nothing to do with air being a mixture (except that nitrogen will actually displace oxygen from solution - we use this for de-oxygenating solutions in the lab sometimes).

Okay, but you're blowing nitrogen through water to de-oxygenate it, not air. Blowing air through water will put some oxygen in the water, but I think it is more to do with the action of getting stirred up and gas exchange at the surface that the bubbles thought the liquid.

So, if oxygen is not soluble in water, when I pump pure oxygen from a cylinder into my fermentors at work (with a water-based medium in them similar to wort), and I see the partial pressure of dissolved oxygen (dO) increasing, what am I measuring? My bacteria - which need oxygen for optimal growth - grow just fine, which they wouldn't do in an anaerobic medium. Please note: I see this with molecular oxygen gas (O2). As an aside, if I use air instead, the dO does not get as high, and my bacteria do not grow so fast. Why would that be?

I don't know. And you know, I don't profess to be an expert at this stuff. I'm a mechanical guy, not a chemical guy. A couple semesters of chemistry and inorganic is all I've got. I'll read up on it some more. I don't dispute that oxygen can be dissolved in water. But diatomic oxygen, is not that soluble. And I don't believe that blowing O2 through your wort does much. Why do we make yeast starters on stir plates? Why don't we make yeast starters with O2 stones and bubblers?
 
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