Dissolved Oxygen Experiment- Interesting Finds with Beer Transfer Method

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micraftbeer

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I recently did a hands on review of a Milwaukee MW600 Dissolved Oxygen meter for HomeBrewFinds. Review linked here. As part of trying out the meter, I did a bunch of different experiments looking at dissolved oxygen. One of them that the results surprised me on was method of beer transfer from finished fermentation to the keg. I mostly am able to do closed transfers now, pushing the beer out of fermentor into keg using bottled CO2, and it seems like that was the best method to reduce oxygen into my finished/kegged beer.

On the fermentors that I can't do a closed pressure transfer, I use a diaphragm pump to transfer the beer. I had thought that with my method and the style of the diaphragm pump it would be pretty low oxygen, but I had no data other than my personal belief.

As a comparator to the above two methods, I did one transfer with a stainless steel siphon. I figured this would be the worst for oxygen pickup. Definitely I thought the open lid of the receiving keg, even though the keg had been CO2 purged, would pick up a lot of oxygen.

It was surprising that the results showed all 3 methods had pretty much the same measured DO in the beers after transfer.

Beer Transfer DO Experiment Results.jpg
 

Bassman2003

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It is a complicated game trying to keep O2 out of everything. Nice to see testing as that is the only way to really get a scope on all of this. Are you liquid sanitizer purging the keg? That and transferring with active yeast (spunding) are the two best ways to go about it. The active yeast will eat up a lot of what we can't eliminate. Open lids are a no go if you want to stop the O2.
 
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micraftbeer

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In the experiment, were the kegs pre-purged?
If so, how?
Yes, important aspect that I forgot to include. All 3 of the kegs were purged with this method:
1. Fill empty keg with water, add StarSan to appropriate mix rate. Close lid on keg
2. Feed water in through hose/disconnect connected to liquid out post while another hose/disconnect hooked up to gas in post.
3. Feed water in until it starts to come out the gas port, then continue filling with water while the PRV is held open until full liquid is coming out the PRV.
4. Hook up gas in to bottled CO2 and push out all the StarSan into bucket or next keg to be purged.
5. Once all the liquid StarSan mix is out, disconnect the lines and leave lid on keg with everything sealed until time to fill.

For the closed transfer, I used a spunding valve on the gas post, and pushed beer in from pressurized fermentor (using bottled CO2 again) and in through the kegs liquid post.

For the diaphragm pump, I had the output from pump hooked up to a ball lock disconnect with a BrewHardware fitting in there so I could pump until the air was pushed out of the line and just beer was coming out. I then connected that disconnect to the liquid out post of keg, and then connected a gas disconnect on the keg with a length of hose to run to the blow-off of the fermentor. That way it was circular in that as the pump pushed beer in, displaced volume from the keg would go in on top of beer in fermentor.

For the siphon transfer, I unscrewed the lid of the fermentor and put the siphon in, popped the lid off the keg and laid the hose in on the bottom, then gave it a pump to get the flow going. It was almost painful opening up the lid of the keg after I had gone through the purge process as outlined before. Once filled, I put the lid on the keg and did 4 cycles of filling the headspace with CO2 and venting through the PRV.
 

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What are the units on that graph?

Is there any method in the user manual to calibrate the meter? I’ve never used one
 

Bilsch

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I recently did a hands on review of a Milwaukee MW600 Dissolved Oxygen meter for HomeBrewFinds. Review linked here. As part of trying out the meter, I did a bunch of different experiments looking at dissolved oxygen. One of them that the results surprised me on was method of beer transfer from finished fermentation to the keg. I mostly am able to do closed transfers now, pushing the beer out of fermentor into keg using bottled CO2, and it seems like that was the best method to reduce oxygen into my finished/kegged beer.

On the fermentors that I can't do a closed pressure transfer, I use a diaphragm pump to transfer the beer. I had thought that with my method and the style of the diaphragm pump it would be pretty low oxygen, but I had no data other than my personal belief.

As a comparator to the above two methods, I did one transfer with a stainless steel siphon. I figured this would be the worst for oxygen pickup. Definitely I thought the open lid of the receiving keg, even though the keg had been CO2 purged, would pick up a lot of oxygen.

It was surprising that the results showed all 3 methods had pretty much the same measured DO in the beers after transfer.
I read your review a while back and unfortunately there were a lot of mistakes made due to not understanding the equipment nor how oxygen interacts with the brewing water and wort. You might benefit from a more intensive review of the science before posting a review like this since it will only serve to confuse others.
 

TheMadKing

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I read your review a while back and unfortunately there were a lot of mistakes made due to not understanding the equipment nor how oxygen interacts with the brewing water and wort. You might benefit from a more intensive review of the science before posting a review like this since it will only serve to confuse others.
Since you seem to know exactly what the problem is, would you care to provide assistance with it? Or would you rather drop a turd in the punch bowl and walk away?

Given the results presented here, I would suspect measurement or sampling error but I have no idea how these instruments work and have never researched the process.
 

Bilsch

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Since you seem to know exactly what the problem is, would you care to provide assistance with it? Or would you rather drop a turd in the punch bowl and walk away?

Given the results presented here, I would suspect measurement or sampling error but I have no idea how these instruments work and have never researched the process.
It’s going to take quite a bit of work to list all the errors and explain why they are incorrect and then outline the science of how to do it correctly. I mean I guess I can but thought it might have been better for the author of this kind of review to get his facts straight before publishing.
 
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micraftbeer

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What are the units on that graph?

Is there any method in the user manual to calibrate the meter? I’ve never used one
The units on the graph are PPM of dissolved Oxygen.

There is a calibration procedure with the meter, which I followed before I did the experiments. There's an adjustment for the 0 point and 100% point. One of them is done in air, one is done with a calibration solution (I can't remember which is which).
 

TheMadKing

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It’s going to take quite a bit of work to list all the errors and explain why they are incorrect and then outline the science of how to do it correctly. I mean I guess I can but thought it might have been better for the author of this kind of review to get his facts straight before publishing.
So not even a hint then?
 

Qhrumphf

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Unfortunately the Milwaukee unit isn't nearly sensitive enough for finished beer, as ideal and problematically high DO measurements for finished beer are both in the lower fringe of it's measurement range where it can't give a reliable reading. It's good for pre-fermentation wort oxygenation measurements ONLY.

The sad fact is a reliable fermentation DO meter is simply too expensive for homebrewers as well as many small professional brewers. You're talking thousands, not hundreds, of dollars, for straight BASEMENT models, and the price of a new mid-size sedan for standard models.
 
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micraftbeer

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Unfortunately the Milwaukee unit isn't nearly sensitive enough for finished beer, as ideal and problematically high DO measurements for finished beer are both in the lower fringe of it's measurement range where it can't give a reliable reading.
Out of curiosity, what is the range of ideal vs. high DO in finished beer? In my use of this meter, I felt like there was a band of repeatability and/or accuracy surely at play, so I was mainly looking for occurrences where large differences showed up. Is it that good vs. bad DO levels are out in the 0.001 PPM range, or is there a physical phenomenon that makes the meter not read accurately in the presence of alcohol?
 

Qhrumphf

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I'd consider any packaged DO over 100ppb to be patently unacceptable (and above 50 is enough to throw alarms). That's at the floor of the Milwaukee's measurement range and well below it's margin of error, ie measurement in that range is unreliable anyway. I target a packaged DO below 20ppb that the Milwaukee cannot even measure.

I use an Anton Paar CBoxQC at work that costs more than my Honda Civic that can read in those ranges. The cheapest option I'm aware of to get close is a Hamilton Beverly and that's still several thousand dollars.
 

sibelman

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I applaud the impulse to measure the effects of different techniques, a frustrating gap in the quest to exclude oxygen at the homebrewing level. Maybe @micraft could pair up with someone with access to adequate measuring equipment. Meanwhile, I'll keep purging kegs and doing closed transfers.
 

TheMadKing

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I use an Anton Paar CBoxQC at work that costs more than my Honda Civic that can read in those ranges. The cheapest option I'm aware of to get close is a Hamilton Beverly and that's still several thousand dollars.
So how much for your Honda Civic?

And how would I go about hooking up a sampling tube to it? 😁
 

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Thanks for trying OP I was hopeful but am sad to be reminded of this limitation. I'd love to get my hands on one of those high end units.

Still I have to ask, shouldn't the 1.2 ppm result for the closed transfer be cause for concern even with the limitations of this instrument? I could see that if the result was down in the range you would be looking for it would be at best an encouraging result at best...but 1200? If measurement was taken properly that should still be a really troubling number, no?
 
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Still I have to ask, shouldn't the 1.2 ppm result for the closed transfer be cause for concern even with the limitations of this instrument?
The other thing that comes to mind is that maybe the zero point drifted, or maybe the meter gets "confused" in the presence of alcohol (like a refractometer). I tried contacting Milwaukee about the effect of alcohol on the readings, but I didn't hear back.
 

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I wonder if what you’re actually measuring is O2 pickup when pouring from keg to glass. The results are fairly comparable and surprising for the closed transfer. O2 pickup during pouring might have masked more subtle differences between the three transfer methods.
 

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I wonder if what you’re actually measuring is O2 pickup when pouring from keg to glass. The results are fairly comparable and surprising for the closed transfer. O2 pickup during pouring might have masked more subtle differences between the three transfer methods.
This was my thought as well.. O2 pickup during the sampling and measuring process would explain why the results are so similar
 
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I wonder if what you’re actually measuring is O2 pickup when pouring from keg to glass. The results are fairly comparable and surprising for the closed transfer. O2 pickup during pouring might have masked more subtle differences between the three transfer methods.
Yes, very well could be. I was trying to avoid opening the kegs after transfer and exposing them to oxygen. So I used a spigot attached to a disconnect and pushed the beer out with bottled CO2.
 

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Just tossing some twigs onto this experiment basis fire: it would be cool to use that Civic-priced reader to measure DO on some bottled and canned beers packaged after a set time to see if there is any change in the end product. 🤔
 

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So not even a hint then?
My hope was to encourage the author to revisit his work before tearing it apart here but you guys are basically forcing this so here goes.

Measuring oxygen ingress in wort or beer is exceptionally difficult because it contains malt and hop derived antioxidants. This means your trying to quantify a moving target. As soon as the oxygen enters the system it is being quickly used up making oxidized compounds. This is why it is somewhat futile to try to measure DO in wort or beer especially during mash or boil. The best you can do is catch momentary spikes of oxygen ingress but these are transitory and easy to miss without capturing and the graphing data from the probe. For this you need expensive in process equipment. Trying to measure DO while not understanding how oxygen interacts with the antioxidants in wort is the biggest problem with said review.

Note: Measuring TPO accurately is possible because they use high quality sensors however the readings must be taken quickly after package sealing, while cold, which helps to slow the oxidative reactions giving you enough time to get an accurate number before the PO has been scavenged up and the reading goes back to zero.

Galvanometric DO sensors are the slowest and least accurate of the types available. Better would be to use a polarographic style that is in process meaning the working end is sealed in the system where there is some minimal amount of circulation flow. Even expensive standard polarographic O2 probes really aren’t designed for sub 0.3 ppm work instead you would want a traces style DO probe which is even more expensive. Optical DO would be better for accuracy and speed however they cannot work above about 50c. The MW600 is basically useless for anything other than measuring the DO levels in wort after oxygenation before pitching yeast. In this case the accuracy of the Milwaukee meter is good enough for the task. Though the operator should know how to properly calibrate his equipment and grasp the concept of what the air cal ppm should be. Lastly he understand how to test with zero solution to see that the meter is operating properly thus confirming what kind of sensitivity it is capable of before posting erroneous data from said meter and making incorrect conclusions based on the bad information. In short you should know how to use the equipment you review.

I didn’t really want to pound on this guy in the open forum but instead posted a reply to the review where is was originally published in hopes the author would make attempts at correction but that was ignored. After he posted the link to the review here I felt it necessary to point out that the work is very problematic and terribly confusing to people trying to learn about the how and why of DO measurement technology in brewing.
 
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eric19312

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OK I get it. For these DO pickup measurements to be meaningful they need to occur shortly after the event else the oxygen reacts with the beer, does it's damage, and then isn't around anymore to detect. So breweries look at oxygen pickup from step to step instead of focusing entirely on TPO at the end?

Could you work around this limitation doing the experiments with deoxygenated water? Perhaps water treated with yeast and sugar and then boiled before being put into a purged conical?
 

TheMadKing

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My hope was to encourage the author to revisit his work before tearing it apart here but you guys are basically forcing this so here goes.

Measuring oxygen ingress in wort or beer is exceptionally difficult because it contains malt and hop derived antioxidants. This means your trying to quantify a moving target. As soon as the oxygen enters the system it is being quickly used up making oxidized compounds. This is why it is somewhat futile to try to measure DO in wort or beer especially during mash or boil. The best you can do is catch momentary spikes of oxygen ingress but these are transitory and easy to miss without capturing and the graphing data from the probe. For this you need expensive in process equipment. Trying to measure DO while not understanding how oxygen interacts with the antioxidants in wort is the biggest problem with said review.

Note: Measuring TPO accurately is possible because they use high quality sensors however the readings must be taken quickly after package sealing, while cold, which helps to slow the oxidative reactions giving you enough time to get an accurate number before the PO has been scavenged up and the reading goes back to zero.

Galvanometric DO sensors are the slowest and least accurate of the types available. Better would be to use a polarographic style that is in process meaning the working end is sealed in the system where there is some minimal amount of circulation flow. Even expensive standard polarographic O2 probes really aren’t designed for sub 0.3 ppm work instead you would want a traces style DO probe which is even more expensive. Optical DO would be better for accuracy and speed however they cannot work above about 50c. The MW600 is basically useless for anything other than measuring the DO levels in wort after oxygenation before pitching yeast. In this case the accuracy of the Milwaukee meter is good enough for the task. Though the operator should know how to properly calibrate his equipment and grasp the concept of what the air cal ppm should be. Lastly he understand how to test with zero solution to see that the meter is operating properly thus confirming what kind of sensitivity it is capable of before posting erroneous data from said meter and making incorrect conclusions based on the bad information. In short you should know how to use the equipment you review.

I didn’t really want to pound on this guy in the open forum but instead posted a reply to the review where is was originally published in hopes the author would make attempts at correction but that was ignored. After he posted the link to the review here I felt it necessary to point out that the work is very problematic and terribly confusing to people trying to learn about the how and why of DO measurement technology in brewing.
Great information thank you for sharing

As to the delivery You've created a false dichotomy where the only two options are to let the auther struggle and figure out all of the problems (unlikely to succeed because we don't know what we don't know) and self correct, or "tear his work apart" and "pound on him"

How about just being polite and offering constructive criticism and helpful guidance? It might serve you better and result in your audience being more receptive, just a thought.

Again, thank you for taking the time to type all this up, it does clearly show the problems with the process.
 

Bilsch

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How about just being polite and offering constructive criticism and helpful guidance? It might serve you better and result in your audience being more receptive, just a thought.
I agree that would be the best approach and I tried that first with comments to the original review however that was ignored. Also we’re not talking about a post here that was a bit misguided but instead a review of a DO meter out in the wild that by all appearances purported to be from a person qualified to do the work. Yes I definitely could have been nicer but things like that raise my hackles.

To the OP: I hope you take the time to learn more about this fascinating subject and possibly think about going back and correcting your review.
 

Bilsch

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So breweries look at oxygen pickup from step to step instead of focusing entirely on TPO at the end?

Could you work around this limitation doing the experiments with deoxygenated water? Perhaps water treated with yeast and sugar and then boiled before being put into a purged conical?
Breweries don't bother looking at DO numbers in the mash but some do check the DO of the strike water and in the piping/tanks before transfer etc. then finally TPO. But remember TPO can’t tell you what oxidation happened in the brewing process, only what was picked up during bottling/canning.

Sure you can check out the tightness of your system by running DO water through it and looking for oxygen ingress. Lots of LoDO guys who own the correct in-process meters do this very thing. You’d be surprised the places that oxygen can sneak in.
 

eric19312

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Breweries don't bother looking at DO numbers in the mash but some do check the DO of the strike water and in the piping/tanks before transfer etc. then finally TPO. But remember TPO can’t tell you what oxidation happened in the brewing process, only what was picked up during bottling/canning.

Sure you can check out the tightness of your system by running DO water through it and looking for oxygen ingress. Lots of LoDO guys who own the correct in-process meters do this very thing. You’d be surprised the places that oxygen can sneak in.
Thanks - yes good to know that's a way to get useful results (once you have access to a good enough meter).
 
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micraftbeer

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I agree that would be the best approach and I tried that first with comments to the original review however that was ignored.
I don't see anything on the website. I submit my reviews to the owner of HomeBrewFinds, who publishes them. I'll see if he had some comments there and if he can forward them to me. One thing I will update is the fact that the experiment of finished beer is trying to measure something in the 20 PPB region, whereas the MW600 has an accuracy of +/- 300 PPB. So that's essentially pointless.

As for the inability of the MW600 polarographic DO meter of measuring DO in wort, I'm going to want to reach out to Milwaukee to get their read on this.

Thanks for the feedback.

And by the way, I'm not offended by this exchange, it's been a ball!
 

TheMadKing

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Breweries don't bother looking at DO numbers in the mash but some do check the DO of the strike water and in the piping/tanks before transfer etc. then finally TPO. But remember TPO can’t tell you what oxidation happened in the brewing process, only what was picked up during bottling/canning.

Sure you can check out the tightness of your system by running DO water through it and looking for oxygen ingress. Lots of LoDO guys who own the correct in-process meters do this very thing. You’d be surprised the places that oxygen can sneak in.
So honest question on this, because something isn't adding up to me:

If the creation of oxidation compounds occurs very rapidly (on the order of seconds to minutes) during the mashing process, so rapidly that you have to continuously monitor the DO level to catch it, doesn't oxygenation for yeast at the end of the boil create those compounds at the same speed? Meaning the no matter how careful you are throughout the process, it's all undone in the 2-4 hours needed for yeast to consume all the oxygen?
 

VikeMan

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I didn’t really want to pound on this guy in the open forum but instead posted a reply to the review where is was originally published in hopes the author would make attempts at correction but that was ignored.
I just had a look at the review. There are (currently) no comments there. Failed Post? Deleted? ¯\_(ツ)_/¯
 

Bilsch

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So honest question on this, because something isn't adding up to me:

If the creation of oxidation compounds occurs very rapidly (on the order of seconds to minutes) during the mashing process, so rapidly that you have to continuously monitor the DO level to catch it, doesn't oxygenation for yeast at the end of the boil create those compounds at the same speed? Meaning the no matter how careful you are throughout the process, it's all undone in the 2-4 hours needed for yeast to consume all the oxygen?
It’s a good question and often the first one people ask when they start to contemplate why anyone would want to reduce oxygen exposure on the hot side when they are just going to aerate the wort before pitching.

The important thing to understand is that heat increases the kinetic energy of molecules therefore chemical reactions happen faster at higher temperatures. This means that the same staling reactions that take minutes in the mash will be slowed down to hours or days after chilling in the fermenter. Healthy yeast are quite capable of mopping up all available DO in less than an hour providing the protection to save your wonderful fresh malt/hop flavors and aromas from being oxidized.
 
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Bilsch

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I just had a look at the review. There are (currently) no comments there. Failed Post? Deleted? ¯\_(ツ)_/¯
Huh.. I wonder why replies questioning the accuracy of a glowing review could fall into a black hole never to been seen again. Also I wasn’t the only one who attempted to comment so i doubt it was an accident they vanished.
 
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