Oxygenating after pitching yeast

I usually oxygenate my wort with a diffusion stone and bottle of benzomatic pure O2 ( the red bottle you can get at Home Depot ). I turn valve until bubbles show and leave on for 60 seconds.

With my last brew I forgot to do this and pitched my yeast do you think this is more harmful than not oxygenating?

I have read that pure oxygen is toxic yeast, which is my concern. I am wondering if any one has actual experience trying O2 before and after pitching and can see a difference in beer.

Thanks!

Just go old school and shake the carboy/bucket for a few minutes. It has the same effect as the oxygen stone, just less convenient, and it's fine to do it after you've already pitched.

I routinely pitch yeast and then oxygenate. I never have any problems. Granted, pure O2 is toxic to yeast, but I doubt that very many cells are actually getting exposed for a period of time capable of killing them. I'm not saying it's the best practice, but I would definitely oxygenate that batch. You'll get much better results than if you don't. Oh, and FYI, for very big beers I've heard of people adding O2 multiple times as primary is ramping up, so I don't think this practice will cause much harm. I also add pure O2 to yeast starters when I step them up with no ill effects.

Thanks for input. I did oxygenate and will update this post to let you know if I perceive different fermentation behavior.

I disagree with the statement that shaking fermenter will do the same as injecting pure O2. There are lots of studies that prove significant increase in O2 levels using pure O2 with diffusion stone compared manual aeration (splashing/shaking). I have also noticed improved fermentation activity when switching to pure O2.

I disagree with the statement that shaking fermenter will do the same as injecting pure O2. There are lots of studies that prove significant increase in O2 levels using pure O2 with diffusion stone compared manual aeration (splashing/shaking). I have also noticed improved fermentation activity when switching to pure O2.

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As I understand it, the yeast only care that you reach the optimum 8 PPM of O2. There's a YouTube video where Wyeast shows that the same 8 PPM of O2 can be achieved with 45 seconds of shaking as with something like 30 seconds of pure O2 from a diffusion stone, both resulting in the same 8 ppm suggested for optimum yeast health (sorry, can't link it...firewalled at work).

I think the pure O2 with a diffusion stone is just more convenient for the brewer. The yeast don't care where the O2 comes from, as long as there's enough to go around.

The Nitrogen and Argon in the air are not adverse to yeast health, and doesn't dissolve as easily as oxygen anyway, so I can't think of any reason it would be adverse to yeast health. There are plenty of pro brewers that will swear beergas (nitrogen/CO2) and even pure argon beer are better than CO2-carbonated beer.

Anyway, just my thoughts. If you know of a good reason pure O2 is better for yeast health than the corresponding PPM from shaking, let me know, but I've just never seen even the yeast labs say that before. They seems to say that shaking and pure O2 are very equal as long as they reach the same 8 ppm O2 result.

TopherM said:

If you know of a good reason pure O2 is better for yeast health than the corresponding PPM from shaking, let me know, but I've just never seen even the yeast labs say that before.

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It's not better, it's just EASIER to achieve the desired PPM when using pure )2 unless you want to shake the hell out of things for 15 minutes.

Again, Wyeast studies say 45 seconds of vigorous shaking to reach the optimum 8 ppm of dissolved O2, NOT 15 minutes. They even have a YouTube video of that very experiment. Go look for yourself.

Was it dry yeast or liquid yeast?

If dry, then it makes no difference at all anyway. If it was liquid, then it would have been better to aerate before pitching, but I think at this point messing with it would do more harm than good. I would assume that you got at least some measure of oxygenation just from the splashing that occurred when trasnferring from your boil kettle into the fermenter.

In the book, Yeast, The Practical Guide to Beer Fermentation, by Chris White, founder of White Labs, and Jamil Zainasheff of Mr Malty, etc. the following is written:

"For the average wort and yeast pitching rates, the proper amount of dissolved oxygen is 8 to 10 parts per million."..."With plenty of headspace, a strong back, and lots of vigorous shaking, a homebrewer can get levels as high as 8 ppm into the wort. This is about the maximum using air."

There is no indication of what "lots" would be, timewise, but a table presenting data from a White Labs experiment indicates that shaking for 5 minutes resulted in 2.71ppm of dissolved O2.

I have a little different technique that I use and would like to get some input. I cool the wort with a heat exchanger so I come out of the kettle through the heat exchanger then I catch the wort in a 1 gallon pitcher which I fill about half way. I then shut off the flow and dump the pitcher back into the kettle. This process takes about 20 min to drop the temperature but it involves several iterations of catching and dumping the wort. My thinking is that the splashing associated with dumping the wort back into the kettle aerates at least as much as shaking the carboy. Then once I have reached the target temperature I drain the wort from the kettle into the carboy with the yeast waiting in the bottom. It seems to work ok although I haven't tried O2

Quoting the same book as two posts above, Yeast, by White and Zainasheff, "The wort splashing devices employed by many homebrewers will result in approximately 4 ppm, less than half the required amount."

FWIW, I have an O2 wand from Willams. I use yeast starters generated on a stir plate. I decant, pitch and run O2 slowly for about 30 seconds in the carboy, then stopper and shake/rock for 20-30 seconds. I believe the additional shaking pushes the concentrated O2 in the headspace into the wort. I have consistently strong fermentations and have never had a stuck fermentation or one that did not reach the projected FG.

Was it dry yeast or liquid yeast?

If dry, then it makes no difference at all anyway. If it was liquid, then it would have been better to aerate before pitching, but I think at this point messing with it would do more harm than good.

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Sorry, Kombat, but this is just stright up incorrect. Dry yeast require dissolved oxygen for optimum health in the exact same way liquid yeast do.

To everyone else, I'm not saying that White Labs and whatever author in whatever book didn't experiment and reach the conclusions you are describing, but I will say that they must be wusses compared to the shakers at Wyyeast, who most certainly produced 8 ppm O2 in a 45 second shake. Maybe they just need to hit the weight room?

Again, I don't have access to the link through my work's firewall, but watch the video on YouTube. A Wyeast scientist literally shakes the crap out of a fermenter and measures the dissolved O2, and gets 8 ppm with 45 seconds of vigorous shaking.

I'm not making this up. It's a documented scientific experiment that you can literally watch for yourself. You don't have to take my word for it (like some of the anedoctal evidence others are presenting).

FROM THE WYEAST SITE (http://www.wyeastlab.com/faqs.cfm#r44)

"Approximately how long do you have to shake a 5 gallon carboy to get oxygen saturation (8ppm)?

45 seconds of vigorous shaking."

FROM THE WYEAST SITE (http://www.wyeastlab.com/hb_oxygenation.cfm)

"Traditional splashing and shaking, although laborious, is fairly efficient at dissolving up to 8 ppm oxygen."

TopherM said:

Again, Wyeast studies say 45 seconds of vigorous shaking to reach the optimum 8 ppm of dissolved O2, NOT 15 minutes. They even have a YouTube video of that very experiment. Go look for yourself.

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When 30-60 seconds of pure O2 is the norm to reach 8-10 PPM, I just don't believe that 45 seconds of shaking is going to get you anywhere near that level.

For reference, here is the Wyeast link for those that want to see it - I just watched it:


Here's the White Labs Head of Lab Operations speaking last year. She starts talking about oxygen and PPM needs around 13:00. Listen through to at least the 15:33 mark. This isn't the only source on this information, but the one that comes to my mind (right now).



Between WhiteLabs, Chris White, and Jamil agreeing on the time, I'm inclined to go with them. Plus, she is cuter than the guy at Wyeast.

Plus, she is cuter than the guy at Wyeast.

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I conceed this point

TopherM said:

I conceed this point

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See? All brewers can agree on SOMETHING

Thanks to everyone for input great to hear other people's view point.

I ferment in 14 gallon conical, so shaking is possible, but more difficult.

I have read lots of literature on the subject and like all things homebrew I take all literature with a grain of salt. I prefer to rely on first hand experience on my decision making process. I started using pure O2 with stone before I bought my conical (I.e in glass carboy). I noticed faster starts to fermentation and attenuation that matched white labs suggestion when moving to pure O2.

Having said all this, the intention of this post was not to compare shaking to O2 injection. I would like to understand if injecting O2 after pitching is doing more harm than good. I already did it, so I should find out this week. Interested to see other brewers experience with this specific question. As with lots of threads here, though, the tangent has provided lots of insight ( and appreciation of the female gender &#128516.

Fwiw, I will continue to oxygenate, but after this "trial" I will figure out whether or mot to skip O2 injection if I brain fart and forget to do so before adding yeast in a future brew.

I have been known to drink a beer or two (ahem) while brewing and this has led to me doing things out of the normal order, like innoculation with yeast prior to oxygenating with 02. I have done this out of order at least 5-6 times (seems I do have a drinking problem, eh?) and I have not ever had an issue with fermentation. I have noticed no difference between doing it that way and the proper order, with all my fermentations showing activity within 3-4 hours. I always do a starter (2 liter usually) and 10G batches. I have even screwed up the first carboy, and done the second one in the proper order and both fermented and tasted the same. RDWHAHB...

Thanks stonebrewer! That is the feedback I was hoping to see. Unfortunately I am now up in the mountains 200 miles away from my fermenter an will not be able to observe initial fermentation behavior. I will note the FG and tast the beer and see if I see any differences.

I am not super concerned that I have "ruined" the beer, but I am very curious which method is better. I know RDWHAHB is the recommendation, but as a engineer/scientist I'm curious how the impact of procedure effects final results.

TopherM said:

Sorry, Kombat, but this is just stright up incorrect. Dry yeast require dissolved oxygen for optimum health in the exact same way liquid yeast do.

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From the Danstar yeast FAQ on their website:

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.

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The only time you would want to skip oxygen is when you pitch enough yeast to negate the replication phase. In other words, overpitch. However, in most cases you want the yeast to replicate because it has a desirable effect on flavor profile, which is where proper pitching rates come in.

BBL_Brewer said:

The only time you would want to skip oxygen is when you pitch enough yeast to negate the replication phase. In other words, overpitch. However, in most cases you want the yeast to replicate because it has a desirable effect on flavor profile, which is where proper pitching rates come in.

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I'm very interested in this question of whether the Danstar dry yeast needs oxygen - could you elaborate on this? Do you disagree with the Danstar statement, or is there some subtle point that makes it case specific? The Danstar info seems like it's meant to apply to all cases...

kombat said:

from the danstar yeast faq on their website:

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+1 I was about to say the same thing.

Since it is dry yeast, and the cell count is probably pretty high per pack oxygen may not be required in order for the yeast to reproduce to a population size capable of fermenting the batch. However, this is not always the case. Yeast cannot reproduce efficiently without oxygen, that is a fact. Once all the oxygen is depleted, they stop reproducing, respirate anaerobically and fermentation begins. At that point all they do mostly is eat, not reproduce. So whatever Danstar is stating, it certainly does not apply to most cases, especially when using liquid yeast.

Does anyone use a mechanical device to oxygenate? I have a home made drill mounted stirring device that will stir a vortex down to the bottom of a 6 gal fermenter in about 10 seconds. I think several pulses would be very effective.

Any thoughts on doing this?

BBL_Brewer said:

Since it is dry yeast, and the cell count is probably pretty high per pack oxygen may not be required in order for the yeast to reproduce to a population size capable of fermenting the batch. However, this is not always the case. Yeast cannot reproduce without oxygen, that is a fact. Once all the oxygen is depleted, they stop reproducing, respirate anaerobically and fermentation begins. At that point all they do is eat, not reproduce. So whatever Danstar is stating, it certainly does not apply to most cases, especially when using liquid yeast.

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Not a fact. Yeast can reproduce anaerobically. They can use other molecules that may be present to construct membranes. Ex: sterols, fatty acids, phosphates, carbon, trace metals, nitrogen compounds.....Their growth may be slowed quite a bit, but they absolutely can reproduce without dissolved oxygen. The reason to oxygenate the wort is to slow lag time, speed reproduction, lower amounts of byproducts, and create much more robust cells.

Vigo_Carpathian said:

Not a fact. Yeast can reproduce anaerobically. They can use other molecules that may be present to construct membranes. Ex: sterols, fatty acids, phosphates, carbon, trace metals, nitrogen compounds.....Their growth may be slowed quite a bit, but they absolutely can reproduce without dissolved oxygen. The reason to oxygenate the wort is to slow lag time, speed reproduction, lower amounts of byproducts, and create much more robust cells.

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Duly noted, learn something new everyday. However, you are not going to get much reproduction without oxygen.

Quick update. Yeast did its job and WLP went from 1.052 to 1.009 in about 10 days. The beer seems a little bit cloudier than usual, but might be unrelated. Will report back after dry hop and cold crashing, but it doesn't appear that oxygenating after yeast pitch had harmful impact on attenuation.

I seem to remember Dr Clayton Cone saying that the optimal time to oxygenate is around 14 hours after pitching the yeast, though I can't find his Q&A session on the homebrew digest. At any rate I always oxygenate after pitching the yeast (sometimes 12 hours later, sometimes immediately) and I've never had a problem.

Found it:

http://www.danstaryeast.com/articles/oxygenation-timing

Beer is kegged and carbed. Only difference I can notice is the beer is a little hazier than normal. Attenuation was right on. Flavors are as expected. I am not sure if adding O2 after pitching can impact haze, but it is the only thing I notice.

TopherM said:

I'm not making this up. It's a documented scientific experiment that you can literally watch for yourself. You don't have to take my word for it (like some of the anedoctal evidence others are presenting).

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The wyeast video seemed much more like a statement and not a repeated/verified scientific experiment. They don't even mention how full the carboy was. I'm just saying I wouldn't hang my hat on a video with a guy making a statement in blue scrubs.

On another note, I know this thread is old and you've probably brewed plenty of batches since, but there is no harm done in oxygenating after you pitch (except the risk of contamination) if you oxygenate during the lag phase (typically 12-24hrs assuming proper pitch rate). In fact, for really big beers (1.100+) you have to do a second oxygenation prior to fermentation commencing if you want full attenuation.

I won't go into depth on the technicalities but as long as a majority of the cells are in the reproduction phase, the oxygen in the wort is being absorbed (within about an hr) by the yeast to prepare their cell walls for division. Once a majority of the cells have moved into the fermentation phase (24hrs +) the addition of oxygen to wort will not be absorbed by the yeast, instead, it will react with a yeast reproduction by-product that has not yet been cleaned up and result in acetaldehyde (green apple), diacetyl, or fusel alcohols. (Yeast, Chrise White & Jamile Zainasheff)

C-Fizzle said:

Once a majority of the cells have moved into the fermentation phase (24hrs +) the addition of oxygen to wort will not be absorbed by the yeast, instead, it will react with a yeast reproduction by-product that has not yet been cleaned up and result in acetaldehyde (green apple), diacetyl, or fusel alcohols. (Yeast, Chrise White & Jamile Zainasheff)

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I'm confused. Is this saying that adding O2 after fermentation starts will result off flavors (acetaldehyde, diacetyl and fusel).

But you also state that sometimes in high OG beers, you need to add O2 late in the cycle. How is this not contributing to off flavors.

On side note, Jamil answered this question in Brew Strong Q and A show. He said it would be next to impossible to have conditions where straight O2 would be toxic to yeast, regardless of when it is added.

Adding O2 once a majority of the cells have started ferrmentation is bad for the beer. The second addition of O2 to high OG beers occurs before fermentation starts. Now knowing when fermentation starts is obviously an art not a science, but in general, it's fine to add oxygen before or after you pitch yeast as long as the majority of them are still in the reproduction phase (typically 0 - 24hrs).

Gotcha. So if adding O2 to a big beer after pitching yeast, do it within 24 hours?

I suppose logic is that the huge pitch needed for big beer will eat up all the O2 in wort and could use more before fermentation really starts?

MNDan said:

I seem to remember Dr Clayton Cone saying that the optimal time to oxygenate is around 14 hours after pitching the yeast, though I can't find his Q&A session on the homebrew digest. At any rate I always oxygenate after pitching the yeast (sometimes 12 hours later, sometimes immediately) and I've never had a problem.

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MNDan said:

Found it:

http://www.danstaryeast.com/articles/oxygenation-timing

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Very interesting. I pitched 05 last night but ran out of oxygen, debating whether I was going to get another tank and try today.....