Stripping oxygen from strike water using CO2

[chipmunk]

I came across mention in one of my brewing science books about how breweries remove oxygen from their liquids by bubbling a stripping gas like CO2 or Nitrogen through them. I would speculate this works because it creates a pressure gradient by flushing the liquid with a pure gas having a very low partial pressure of oxygen. As the stripping gas bubbles through the liquid, the oxygen diffuses out of solution and into the gas where it is vented. So... assuming you wanted to reduce the dissolved oxygen content of your strike water, would it be feasible to attach a diffusion stone to your CO2 tank and bubble CO2 through your strike water to lower the dissolved oxygen ? it seems we are able to oxygenate the wort to 10ppm with only a couple of minutes of diffusion, I wonder how long it would take for CO2 gas to remove the oxygen?

 

[Brooothru]

Why do that or speculate how long it would take (not to mention the waste of CO2 and reintroduced oxygen in the bottled CO2)? Just fill your mash tun with strike water, heat to 95F, add 2 grams per gallon common bread yeast, and wait :30 mins to an hour. The yeast will consume virtually all of the dissolved oxygen in your strike water.

Then heat your strike water to mash-in temperature and proceed as normal with your brew session. The D.O. will remain near zero for several days after treatment and will continue working until the yeast are denatured, usually around 110F. I've been doing this for 8-9 months now, though it was challenging during the early stages of lock down finding bread yeast.

The process is called Yeast Oxygen Scavenging and you can find some compelling data of it's efficacy on the German LOB brewer's website.

Brooo Brother

 

[Nick&Worty]

Forgive my ignorance if this is a stupid question, but don't we want oxygen at this stage for pitching yeast? Like.. I intentionally add it.

 

[Tobor_8thMan]

Lots of O2 are driven off during the boil. That's why injecting O2 or splashing the wort, after reaching or below the correct temp is important (for the yeast).

Why worry about O2 in the mash? AFAIK, O2 making our brew stale doesn't happen at the mash stage.

 

[Brooothru]

Forgive my ignorance if this is a stupid question, but don't we want oxygen when pitching yeast? Like.. I intentionally add it.

Absolutely, in the case of liquid yeast (technically, dry yeasts bring their own oxygen to the party). But oxygen in the mash and the boil is bad until you are pitching the yeast into the wort. The LOB folks even say to pitch the yeast first, then oxygenate the wort. The yeast will then consume the O2 before it negatively affects the wort.

Brooo Brother

 

[Nick&Worty]

Absolutely, in the case of liquid yeast (technically, dry yeasts bring their own oxygen to the party). But oxygen in the mash and the boil is bad until you are pitching the yeast into the wort. The LOB folks even say to pitch the yeast first, then oxygenate the wort. The yeast will then consume the O2 before it negatively affects the wort.

Learn something every day! Had no idea oxygen was bad to have in mash. Thanks!

 

[Brooothru]

Lots of O2 are driven off during the boil. That's why injecting O2 or splashing the wort, after reaching or below the correct temp is important (for the yeast).

Why worry about O2 in the mash? AFAIK, O2 making our brew stale doesn't happen at the mash stage.

I can hear screams of anguish and heads exploding on the LOB forum.

O2 at ANY stage in the process, from crushing grain and collecting strike water to filling the keg is bad for your beer. Commercial brewers track it and take steps to minimize it. Does that mean that your beer will be crap if you don't adhere to LoDO procedures with zealot-like devotion? Of course not.

But your beer will be 'better' if you do. It's just a matter of 'how good' is 'good enough' to satisfy your brewing objectives. I've been progressively modifying my brewing methods little by little where I can for the last year or more, and although I don't slavishly fall in lockstep with every LOB protocol I can say that my beers have gotten better and are maintaining their better quantities longer. And it really doesn't take a lot of time, effort or expense to incorporate many of the LOB procedures. All it really takes is an open mind and the willingness to try something different from the way you've always done it before.

Brooo Brother

 

[Tobor_8thMan]

Interesting...

 

[chipmunk]

Why do that or speculate how long it would take (not to mention the waste of CO2 and reintroduced oxygen in the bottled CO2)? Just fill your mash tun with strike water, heat to 95F, add 2 grams per gallon common bread yeast, and wait :30 mins to an hour. The yeast will consume virtually all of the dissolved oxygen in your strike water.

I’ve never tried that yeast method - but I would question how dried yeast would be able to “reach” all of the oxygen in the liquid In that short amount of time. I mean diffusion is like 10,000 times slower in water than in air, so how does the oxygen reach the yeast cell membrane? Do you wait until the yeast is hydrated and then mix? My thinking was if I could scavenge all the O2 with 5 to 10 min of CO2 injection, you could do it while heating up the strike water and save time off the brew day. Now if it takes like 60 minutes and a crap load of CO2 then ... ya dumb idea.

 

[Brooothru]

I remember the gas scavenging method being discussed (theoretically) on this forum, but never went so far as to try it. The yeast scavenging was talked about at length by several of the LOB forum members and is described in detail on that website. They had some impressive empirical data to back up their assertions. Using lab quality equipment they recorded D.O. levels over time that showed oxygen levels falling rapidly (within minutes) to barely detectable levels and remaining there for literally days in a covered kettle. They tested using expensive brewing yeast and inexpensive bread yeast and saw little difference in performance.

I usually fill my kettle, heat it to 99-101F, sprinkle the yeast on top, cover the pot, and call it a night. In the morning I start heating the water and crushing the grains. By then the water is up to temperature and I dough-in.

Disclaimer: I don't own a D.O. meter and can't independently verify the levels of oxygen in my strike water. But the data obtained by the LOB folks appears legit (why would they lie?) and the process is so easy to replicate it seems crazy not to do it.

Brooo Brother

 

[Tobor_8thMan]

Huh? " I usually fill my kettle, heat it to 99-101F, sprinkle the yeast on top, cover the pot, and call it a night. In the morning I start heating the water and crushing the grains. By then the water is up to temperature and I dough-in. "

Making a sour or some other type of concoction? 99-101F for yeast is high. Mash temps for yeast are way too high.

 

[Brooothru]

Huh? " I usually fill my kettle, heat it to 99-101F, sprinkle the yeast on top, cover the pot, and call it a night. In the morning I start heating the water and crushing the grains. By then the water is up to temperature and I dough-in. "

Making a sour or some other type of concoction? 99-101F for yeast is high. Mash temps for yeast are way too high.

No, bread yeast (Fleischmann) propagation is recommended at 95F to 104F, which is about the same temperature for rehydration of most dry beer yeasts. True, most beer yeasts will be denatured by 110-115F, but the proofing temperature for most baking and brewing yeasts is in the 90-104F range.

Brooo Brother

 

[Nick&Worty]

Obviously I'm just learning about this, but question. So by the time your water has reached strike temp, you're pretty sure all the bread yeast is dead, so there's 0 chance it can start eating things while you're mashing? Reading that bread yeast dies at 140. Do you wait a few minutes at temp to be sure all the water is heated through, or just go right at it?

 

[Brooothru]

Obviously I'm just learning about this, but question. So by the time your water has reached strike temp, you're pretty sure all the bread yeast is dead, so there's 0 chance it can start eating things while you're mashing? Reading that bread yeast dies at 140. Do you wait a few minutes at temp to be sure all the water is heated through, or just go right at it?

Really don't think it's an issue. I mash in at 55C/131F. Bread yeast would mostly if not entirely be gone by then. Even if they weren't they would be soon. My first mash step after dough-in is usually 62C/143F. Beta amylase is active at 131F and is converting starch to sugar, that's true, but any yeast activity would be mostly denatered, or wouldn't have time to start fermenting the tiny amount of sugars present in the wort. Any effects that a minute amount of surviving bread yeast would have on the wort would be inconsequential at best and would soon cease anyway as temperatures increased.

Brooo Brother

 

[Nick&Worty]

Thanks. Rabbit holes are my thing.

 

[Nick&Worty]

Wait... that sounded wrong... yknow what.. nevermind lol

 

[day_trippr]

lmao!

 

[Bench]

Why do that or speculate how long it would take (not to mention the waste of CO2 and reintroduced oxygen in the bottled CO2)? Just fill your mash tun with strike water, heat to 95F, add 2 grams per gallon common bread yeast, and wait :30 mins to an hour. The yeast will consume virtually all of the dissolved oxygen in your strike water.

Then heat your strike water to mash-in temperature and proceed as normal with your brew session. The D.O. will remain near zero for several days after treatment and will continue working until the yeast are denatured, usually around 110F. I've been doing this for 8-9 months now, though it was challenging during the early stages of lock down finding bread yeast.

The process is called Yeast Oxygen Scavenging and you can find some compelling data of it's efficacy on the German LOB brewer's website.

Brooo Brother

2 grams per gallon of yeast and 2 grams per gallon of a simple sugar are required. One without the other won't work.

 

[hopfenstopfen]

I remember the gas scavenging method being discussed (theoretically) on this forum, but never went so far as to try it. The yeast scavenging was talked about at length by several of the LOB forum members and is described in detail on that website. They had some impressive empirical data to back up their assertions. Using lab quality equipment they recorded D.O. levels over time that showed oxygen levels falling rapidly (within minutes) to barely detectable levels and remaining there for literally days in a covered kettle. They tested using expensive brewing yeast and inexpensive bread yeast and saw little difference in performance.

I usually fill my kettle, heat it to 99-101F, sprinkle the yeast on top, cover the pot, and call it a night. In the morning I start heating the water and crushing the grains. By then the water is up to temperature and I dough-in.

Disclaimer: I don't own a D.O. meter and can't independently verify the levels of oxygen in my strike water. But the data obtained by the LOB folks appears legit (why would they lie?) and the process is so easy to replicate it seems crazy not to do it.

Brooo Brother

After you heat your kettle to ~100F & add yeast, then you turn off power & the temp will fall overnight, correct? Also, when would/do you add campden tablets & brewing salts? Thanks in advance.

 

[Brooothru]

2 grams per gallon of yeast and 2 grams per gallon of a simple sugar are required. One without the other won't work.

Ooops! Forgot to include it. You're absolutely right. Here's a quick excerpt from the LOB website:

"We find for us, the dextrose/bread yeast is the best bang for your buck and it is very easy to scale off of this test by using the dextrose and a dry bread yeast at a rate of twice your batch volume (not beer batch, water needed for deoxygenation) in grams (i.e. 5 * 2 = 10 grams each of dry bread yeast and dextrose). Or 2g/gal for easy dosing."

Sorry if it caused any confusion. I actually premixed a jar of dry bread yeast and dextrose a few months back and store it in the beer fridge. The jar was an empty Fleischmann's yeast jar and I kinda' forgot about the whole "sugar" thingy. It happens at my age. Now where'd I put my beer?

 

[Gozie Boy]

And if you use a HLT, then it would appear that there will be dead yeast and yeast products at the bottom of that kettle. Meaning that there will then be an additional cleaning step after the brew day, whereas without yeast the HLT was basically clean and good to go for the next brew. So maybe not quite as 'quick and easy' for the 3v folks. Goes into a "work/benefit" analysis, like many other optional steps.

 

[Brooothru]

After you heat your kettle to ~100F & add yeast, then you turn off power & the temp will fall overnight, correct? Also, when would/do you add campden tablets & brewing salts? Thanks in advance.

Yes, the heat gets turned off. The thermal mass of 10 gallons of water in a jacketed kettle with the lid on in a 68F ambient room will retain its heat for a few hours. Even after it reaches stasis with room temperature, the yeast will still be active, consuming dissolved oxygen for quite some time.

 

[Brooothru]

And if you use a HLT, then it would appear that there will be dead yeast and yeast products at the bottom of that kettle. Meaning that there will then be an additional cleaning step after the brew day, whereas without yeast the HLT was basically clean and good to go for the next brew. So maybe not quite as 'quick and easy' for the 3v folks. Goes into a "work/benefit" analysis, like many other optional steps.

There are certainly dead yeast left behind but it's only a very light milky coating on the surfaces of the HLT. It wipes off without scrubbing (at least on stainless steel), usually just rinsing off with sprayer water from the sink. I've never done this process in an Igloo cooler setup, though I can't see where it would create any big problems seeing how easily it cleans up off stainless. There's no thick, sticky krausen like there is in a fermentation vessel.

I brew in an all-in-one electric kettle (Braumeister), so once the strike water goes in it doesn't come out until it's pumped into the fermenter. The heating coils are in direct contact with the strike water/wort the entire time. In the morning when I start heating for the mash, the YOS water with bread yeast has been in the kettle overnight and then gets immediately exposed to 3,000 watts of direct contact with the coils, although there is continuous circulation for the next three hours (90 minutes step mash and :75 minute boil, with intermittent pump breaks). After doing about 15 of these sessions, I've never had any scorching or sticky residue on either the coils or the sides or bottom of the kettle. Cleanup is no more difficult than it was before using this technique.

 

[TLaffey]

I came across mention in one of my brewing science books about how breweries remove oxygen from their liquids by bubbling a stripping gas like CO2 or Nitrogen through them. I would speculate this works because it creates a pressure gradient by flushing the liquid with a pure gas having a very low partial pressure of oxygen. As the stripping gas bubbles through the liquid, the oxygen diffuses out of solution and into the gas where it is vented. So... assuming you wanted to reduce the dissolved oxygen content of your strike water, would it be feasible to attach a diffusion stone to your CO2 tank and bubble CO2 through your strike water to lower the dissolved oxygen ? it seems we are able to oxygenate the wort to 10ppm with only a couple of minutes of diffusion, I wonder how long it would take for CO2 gas to remove the oxygen?

I've been experimenting with this some to get a rough idea of how much gas and time are required. I've tried both CO2 and N2. They both work, but with the size of my HLT, I'd say they are both inefficient. Yesterday I heated my strike water, initially at about 60*F and 5.2ppm O2 and ending at 122*F and 1.1ppm O2 about an hour later (1L/m N2). I've seen an article (https://www.researchgate.net/public..._Gas-Stripping_Column_for_Deoxygenating_Water) that suggests much more efficient methods can be constructed, so I've not entirely given up on this idea.

 

[Bassman2003]

One can also bring your strike water to a boil for five minutes and all of the O2 will be driven off as well. You would then need to chill down to mash-in temps. The yeast scavenging method is easiest and works well.

 

[TLaffey]

One can also bring your strike water to a boil for five minutes and all of the O2 will be driven off as well. You would then need to chill down to mash-in temps. The yeast scavenging method is easiest and works well.

I agree with that. I've used the yeast+sugar method with good results. My little brew day experiment was fun, but from the standpoint of time and effort, I'm going to work out how to chill boiling water from my HLT as it flows to my MT.

 

[Brooothru]

One can also bring your strike water to a boil for five minutes and all of the O2 will be driven off as well. You would then need to chill down to mash-in temps. The yeast scavenging method is easiest and works well.

^^^THIS^^^

Before using YOS, I pre-boiled strike water. However, the LOB brewers' work suggests that the strike water starts reabsorbing O2 almost immediately after stopping the boil and continues throughout the chilling to strike temperature as well as into the mash. YOS keeps working until the yeast are denatured during higher mash temps. Using a mash cap helps to mitigate re-oxygenation, and the effects of oxygen on beer stability are cumulative. Every little bit helps.

The LOB data show that YOS outperformed boiling water and resulted in less D.O. for a longer period of time. It can be done hours ahead of time with no degradation and doesn't require using extra gas or electricity. Neither do you have to boil, then immediately chill, strike water down to mash-in temperature.

Brooo Brother

 

[Bassman2003]

I use YOS for most beers except for hefeweizen where I do a 111F rest. This temp is too low to kill the YOS yeast, so pre-boil is needed. You want to kill the yeast before they come into contact with any sufites. Down the rabbit hole!...

 

[Brooothru]

I use YOS for most beers except for hefeweizen where I do a 111F rest. This temp is too low to kill the YOS yeast, so pre-boil is needed. You want to kill the yeast before they come into contact with any sufites. Down the rabbit hole!...

That's a good point, but what exactly is the interaction between the yeast and sulfites? I don't usually brew hefe, and do protein rests at the high end (55C/131F) if I do one at all. Just curious what the issues are regarding sulfites and yeast.

Brooo Brother

 

[Bassman2003]

Basically the yeast does not react well to sulfites. I can not speak to the exact chemical interactions, just relaying the experiences in the low oxygen community. It is best to keep them separate. Kill the yeast from YOS before strike and oxygenate heavy to expend all of the sulfites right before pitching. One of the weird quirks of low oxygen brewing at the homebrew level since sulfites are our best tool in the toolbox.

 

[chipmunk]

I've been experimenting with this some to get a rough idea of how much gas and time are required. I've tried both CO2 and N2. They both work, but with the size of my HLT, I'd say they are both inefficient.

Very cool! I read on one of the forums about someone using steam as a stripping vapor. This idea is interesting to those of us with low powered electric rigs... Unfortunately santa didn’t bring me a DO meter this year so can’t really experiment.

 

[Franz]

Basically the yeast does not react well to sulfites.

Sorry if this is a stupid question but this refers to Potassium metabisulfite too or something else?

 

[Cool_Hand_Luke]

Very cool! I read on one of the forums about someone using steam as a stripping vapor. This idea is interesting to those of us with low powered electric rigs... Unfortunately santa didn’t bring me a DO meter this year so can’t really experiment.

Steam is very commonly used in industrial plants or power plants to remove oxygen from the boiler feed water to prevent corrosion in the system. It’s run in a counter flow arrangement against the feedwater in a vessel called a deaerator. The water flows down across a series of trays to maximize contact time as steam flows upwards. Low pressure steam is typically used (around 5psig). It is effective but I’m not sure if scaling to the homebrew level would make much sense. Might be simpler to use some of the other methods described here.

 

[Bilsch]

I can hear screams of anguish and heads exploding on the LOB forum.

All it really takes is an open mind and the willingness to try something different from the way you've always done it before.

Not at all, I think you have covered it nicely.

 

[Bilsch]

Sorry if this is a stupid question but this refers to Potassium metabisulfite too or something else?

It's just shorthand for either Sodium or Potassium metabisulfite.

 

[Bilsch]

And if you use a HLT, then it would appear that there will be dead yeast and yeast products at the bottom of that kettle. Meaning that there will then be an additional cleaning step after the brew day, whereas without yeast the HLT was basically clean and good to go for the next brew. So maybe not quite as 'quick and easy' for the 3v folks. Goes into a "work/benefit" analysis, like many other optional steps.

It's true there is a yeast residue left in the HLT but IME it's takes way less time and effort to clean that out then heating to boiling and cooling before strike. There are others that prefer to boil and so it's nice to have choices. Try it both ways and see which way you like best.