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O2 infusion during fermentation?

I am on day 3 of my fermentation. I was thinking about infusint oxygen on day 3 or 4 of my fermentation, after the air lock has stopped. I was thinking that the yeast may be out of oxygen. Good idea, or bad idea?

Bad… the oxygen is just for yeast reproduction. That should be over, and they should be feasting now.

I’ve heard of adding oxygen 12 to 18 hours after an active fermentation start for a very, very high gravity beers, but not as a general practice for high to moderate gravity beers.

Very, very high ABV beers are not my thing so no first hand experience.

The oxygen is only used during the respiration phase of the yeast cycle. During that time the yeast reproduce and make themselves healthy. If oxygen is present, theoretically little to no etOH is produced. After the respiration cycle uses up all available oxygen, fermentation stage begins. That’s where the important work for us takes place.

Very interesting. Thanks for the feedback. So ultimately adding O2 wouldn’t really help?

Out of curiosity, what are you trying to help? Is there a problem you’re trying to address by adding oxygen?

No problem really. I just thought that it might make my beer better. Maybe cleaner or something. I make very good beer. I was just thinking of different ways to improve.

Yeah adding O2 at this point could only hurt. I would think to use the method flars mentioned you would want to add it while still in the respiration phase.

Yeah. I mean. That makes sense. Otherwise, why would you use an airlock if O2 was a good thing. Thanks

The airlock is to keep out microbes that might infect your beer. The outward pressure of CO2 keeps anything from entering including O2. Even after the lock stops bubbling there is a blanket of CO2 protecting the beer.

Your are right about feeding the wort O2. Just do it as soon as the wort is in your fermenter then let it do it’s magic.

I add oxygen only once i did transfer it to primary fermentor. Than pitch yeast. My yeast a happy camper

O2 during ferm is bad bad bad bad bad. Don’t do it, not even a little.

Adding oxygen at the time of yeast pitch, or very soon after is a good thing, especially if you do a yeast starter to get up to optimal pitch rate. The yeast wants O2 for initial reproduction. Later on, however, you do not want O2. Chris White and Jamil Zainasheff’s book “Yeast” discusses yeast’s need for oxygen and aerating wort with pure oxygen in Chapter 4. I’ve been using a Northern Brewer Oxygenation Kit for quite a while now with good results. I aerate for about 40 seconds at the time of yeast pitch. I’ve heard of brewers waiting a few hours to aerate, and as flars said, adding more O2 in the 12 to 18 hr range for very high gravity brews but I’ve never tried it.

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