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Too much O2?

One of the new toys I got for my birthday was the NB oxygen kit. In the past, I have used an aquarium pump with filter and blown oxygen into the wort until it foamed up to the top or 15 minutes passed - usually the former. Without having done any research, I foolishly applied the same approach with my little red can of pure oxygen. It didn’t foam up. The little red oxygen tank ran out. I THEN did some research - I have the White/Zainasheff book, Yeast - and I’m posting to share this mishap and to declare it an unintentional experiment. I realize now that a minute and a half or two would’ve been sufficient. There is no good to come of it - the book - Yeast - states excess oxygen may produce fusel alcohol - I’ve also read that wort can only absorb only so much O2. am now obviously going to wait and see. The beer made was a dry irish stout which, if I’m going to screw up, is perhaps a more forgiving style. I used Safale S-04 and have the ferment temp dialed in at 65. I’m interested to read your thoughts and will post results later.

I’ll bet the beer is fine. It sucks about wasting $10 on a tank for one batch though. Still, no denying you’ve purged any manufacturing residues from the stone.

I’ve seen one or two very experienced brewers say that they’ve killed yeast by using too much pure O2, esp in starters. So they pitch after aerating. What sequence did you do it?

I’ve not experienced this myself, but I tend to be pretty moderate on the pure 02, usually a minute tops.

I aerate before pitching. The yeast have been doing their job - nothing irregular so far in the ferment process.

Pitched on Saturday - just took a gravity reading and after three days it’s at 1.024 - seems normal - it’s still bubbling - not as vigorously, but that is as it should be. Tasting of sample did not reveal anything disconcerting - tasted like a green (as in not matured) dry irish stout. Am a bit concerned over fruity esters as I have since read about Safale S-04 producing more than many like - did not pick up anything in that regard, but they’re not done yet.

The canister was $7.50 at Menards - but still I tried to save a few pennies on the yeast and have good success with dried yeasts in general - then I go and toss $7.50 as an offering to the gods of ignorance :frowning:

I’m hoping to reuse the yeast on an ESB. If this tastes okay at kegging, will there be some kind of evil mutation as a result of all this O2 exposure?

Given you aerated first & pitched second, I bet they’re fine. If it tastes good at kegging, you should be good to go.

afaik, petite mutants are more likely to arise from a lack of o2, or other stresses, than having fully saturated o2. True, oxygen can do a lot of damage, but if there are no worrisome signs in the first batch, I’d run with it. You would probably end up with a very very healthy and plentiful yeast cake, I would guess.

I like baseless opinion and coffee-table conjecture as much as anybody, but thought I’d throw in something from the Yeast book by White and JZ:

Excessive use of pure oxygen results in high levels fusel alcohols, increased acetaldehyde, and other flavor problems.

Also, they note that one minute of pure 02 results in 9.2 ppm and two minutes yielded 14 ppm, under the parameters of their test. Another chart of theirs shows that one craft brewery was getting up to 36 ppm (without knowing it, probably).

I didn’t see anything about effects (of over-oxygenating) on the yeast, long term. So, I’ll stand by my conjecture for now… that if this batch tastes ok, the cake is probably ok.

AND i have to wonder what the maximum solubility of oxygen is anyway. I bet you exceeded it before the tank ran out. Anybody know?

but it sure sounds like this batch might be funky. sorry. hope it’s good despite that!

If you use dry yeast, you really don’t need to aerate.

Got me thinking: If they can make a bacon beer - sounds gross - why not make a new car smell beer? :wink:

I did a quick look around the web and it seems, based on yeast cell numbers from dried, this is true. Seems so counterintuitive though. I mean living organism. Must have oxygen. Oxygen good. Is my caveman thinking - at least before fermentation gets going then - oxygen:bad. Given my idiocy with the first application, I feel I should turn the crank and turn it off after a minute a few times into some future batches regardless - just to feel reassured that I can actually use my oxygen correctly.
If it turns out okay, will do a one minute blow when I repitch or pitch onto the cake.

One small additional note: the OG was 1.044

Got me thinking: If they can make a bacon beer - sounds gross - why not make a new car smell beer? :wink:

I did a quick look around the web and it seems, based on yeast cell numbers from dried, this is true. Seems so counterintuitive though. I mean living organism. Must have oxygen. Oxygen good. Is my caveman thinking - at least before fermentation gets going then - oxygen:bad. Given my idiocy with the first application, I feel I should turn the crank and turn it off after a minute a few times into some future batches regardless - just to feel reassured that I can actually use my oxygen correctly.
If it turns out okay, will do a one minute blow when I repitch or pitch onto the cake.

One small additional note: the OG was 1.044[/quote]

I believe because oxygen’s main role in the process is increasing cell count or “growing the culture”. Since dry yeast contains a larger cell count, this portion of the process is less important. aT least that’s my understanding. Someone correct me if I’m wrong.

What do you do with your spent O2 cans? My recycling won’t touch 'em as they understandably fear it may not be spent. I checked with my nearby Oxygen Services Company - great place - and they stock/swap beer gas as well as CO2, but the don’t futz with these little O2 cylinders.

Depends a little bit. For a beer under 1.065 then 60 seconds of o2 is good. Above that then I’ll go 90 seconds, that’s it.[quote=“jtb”]What do you do with your spent O2 cans? My recycling won’t touch 'em as they understandably fear it may not be spent. I checked with my nearby Oxygen Services Company - great place - and they stock/swap beer gas as well as CO2, but the don’t futz with these little O2 cylinders.[/quote]

If Home Depot sells It shouldn’t they take it back? At least you could drop of your spent tank and get a new one. They don’t do that. Hmmm.
That SUCKS.

Interesting question. If recycling won’t touch em and nobody takes them back that means you either send them to the landfill or start stock piling empties? Not sure I see another option.

[quote=“jtb”]I did a quick look around the web and it seems, based on yeast cell numbers from dried, this is true. Seems so counterintuitive though. I mean living organism. Must have oxygen. Oxygen good. Is my caveman thinking - at least before fermentation gets going then - oxygen:bad. Given my idiocy with the first application, I feel I should turn the crank and turn it off after a minute a few times into some future batches regardless - just to feel reassured that I can actually use my oxygen correctly.
If it turns out okay, will do a one minute blow when I repitch or pitch onto the cake.

One small additional note: the OG was 1.044[/quote]

But you need to think about why you aerate. It’s not that the yeast needs to “breathe”. Yeast use O2 to synthesize sterols. The sterols make the cell walls more flexible so that budding and reproduction is easier. Because dry yeast has so many more cells than liquid, the need for reproduction i minimal to non existent.

6 days in - gravity reading at 1.010 - no noticeable off flavors yet. Nothing unusual about appearance. Cake is not unusually large.

19 days in - racked to secondary today - no kegs to move the stout to and needed the yeast. FG was 1.009 and tastes fine fine fine.

I thought for sure there’d be some fusel warmth or some green apple hiding in the roasty background, but nope. Really nothing off about it.

So if someone should ever dump a whole bottle of O2 into their dry irish stout, everything is gonna be okay.

And no I did not aerate after pitching the esb wort onto half of the stout cake.

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