Can you “over-oxygenate” the batch at pitching time. I ask this because I used pure O for the first time while brewing my last two batches (30 seconds at 5L/min flow) and put into the 7 gal. bucket primaries.
Just an hour ago, the airlock filled up and plugged…and I felt the need to put a blow off tube onto the primary. I put on on the other batch in case the cause was the oxygen…btw…the hyperactive primary is a wheat beer with an OG of 1.040.
I hear it can be done. I use a morebeer o2 valve with a red tank. I turn it on till it starts bubbling and then move it around the bottom till there’s an inch or so of foam. Pretty scientific. Never had a too much O2 issue.
I have a larger oxygen tank (679 L) with a flow regulator, medical grade tubing…then went up pet smart and bought a 3" aquarium stone. Soaked the stone in starsan for an hour and let’er rip…seems like the process works so maybe need to reduce the flow just a bit. ;D
I think one liter per minute for about 60 sec on little beers 90 on big ought to do it. I saw a chart someone did on how rapidly wort reaches saturation. It showed that with pure O2 it happens way quick. Beyond that you’re not doing much.
I wish someone with a chem and yeast background and the instruments would put this to rest. It seems to me that yeast are going to uptake whatever is max soluble. Then they start making beer. I hear people who over oxygenated got fusel alcohol. Maybe, but what were their temps?
I look at it this way. Lots of folks make great beer just shake aerating. So a little O2 is all you need.
There are a lot of posts talking about boiling your stone, rather than star san, as it can clog the stone’s pores. Doesn’t help with your question just a little pointer
Is it really true that you can over oxygenate? O2 is not very soluble in water, much less so than CO2. If it is possible what are the ill effects? If not, it just seems like a lot of wasted O2.
It is possible but it is really very hard to do it unless you have a very small volume like a starter. You would have to have the wort very cold for one thing. And you’d have to have a very good diffusion stone and go very, very slow. Most homebrewers go way too fast when they use pure 02 and are probably getting a lot less oxygenation than they think. For a 5 gallon batch I go 60 seconds for ales and 2 minutes for lagers out of my diffusion stone and it seems to do the trick.
Were there a lot of bubbles coming to the top of the wort? If there were the O2 was not fully getting into the wort, you did end up with O2 in the headspace.
As other have said, I do 1 liter/min. for a 5 gallon beer.
This. At 5L/minute I’m guessing most of the O2 just bubbled through the wort and out. I set my regulator almost as low as I can get it without it shutting off.
I’ve posted this before but it’s interesting. As you all will see there were some limitations to the experiment and it didn’t test using pure oxygen, but makes me question whether I even want to buy O2 aeration equipment, something I’ve been strongly considering lately.
Edit: it does mention over oxygenation is bad but doesn’t indicate what that level of oxygen saturation is.
FWIW, I’ve used O2 through a wand and had good results. But I’m using the mix stir now on all my beers (even on BIG beers), and can’t tell any difference in attenuation or overall beer quality. The key being to aerate until the foam is at the top of the bucket. I’d be curious how this method compares with O2 analytically, but since I can’t find (or measure) any difference I’ll stick with it.
Little red can and wand…60 sec for avg gravity ale, 90 seconds for average gravity lager. Never let it get more than a slight surface ripple…long and slow.
Thanks for the article link bboy…just read through and I have a couple takeaways:
High airflow rates (near 1.0 L/min) were significantly better (faster) at increasing the oxygen levels than low airflow rates (near 0.1 L/min).
Aeration stone (2 um pore) also improves ability to increase oxygen levels
Rocking and shaking was quicker than pumped air aeration…looks like it starts to level off at 10 minutes
In addition, the article states “…and there is some risk of toxicity to the yeast from over-oxygenating wort. Saturating wort with pure oxygen is likely to be toxic to the yeast.” Hmmm…that statement appears to conflict with the Wyeast website (http://www.wyeastlab.com/hb_oxygenation.cfm) which states “Some yeast strains have higher oxygen requirements than others. It is generally safe to assume that you need at least 10ppm of oxygen. 10ppm will supply adequate oxygen in most situations. Over-oxygenation is generally not a concern as the yeast will use all available oxygen within 3 to 9 hours of pitching and oxygen will come out of solution during that time as well. Under-oxygenation is a much bigger concern.”
So…maybe you really can’t over oxygenate (at least near the levels achievable by a brewer’s typical or normal means).
Where does this leave me? Next time I think I will oxygenate first, then pitch the yeast…and going to run oxygen at 1 L per minute for 60 seconds - 90 seconds depending on the gravity. And pick up a wand to replace the aquarium stone (stone will be the backup or I can use to oxygenate my minnows).
I recall a brewer on another forum emptying an entire red can of oxygen into his wort on accident. Likely the speed at which he was pumping the o2 in prevented it from staying in solution. He didn’t note any off flavors, but I’d hardly recommend it! In short, the article referenced may be correct if you could actually saturate the wort with oxygen but Wyeast is also correct when stating it isn’t really a concern.
I use in-line oxygen and a high quality Hach dissolved oxygen meter in the fermentor to establish my baseline O2 levels. (All my beers start out >1.080.) I am amazed how quickly the oxygen comes out of solution once transfer is complete and the O2 sat begins to plummet at 65 degrees. This has prompted me to quickly pitch my yeast without delay. Oxygen toxicity? Doubt we can perform this feat with our equipment. All that extra oxygen is just leaking into the surrounding atmosphere.