Covid brain fart... I oxygenated beer by accident

Discussion in 'Homebrewing' started by GeeL, Mar 27, 2020.

  1. GeeL

    GeeL Aspirant (202) Aug 27, 2008 Massachusetts

    I sometimes add a shot of oxygen on day one of fermentation, especially for higher ABV beers. I've been overworked and stressed and lost track of days and gave a shot of oxygen at the end of day 2. I even noticed that activity was slowing down. I don't know what I was thinking. And, I lost count of seconds and did more than I usually do, I'd guess I did 15 seconds or so at a medium bubbly rate.

    I drew a sample today with a dip tube and it states stale.

    Question: if I add more yeast, do you think it will help? Tomorrow will be day 5.

    It's not a cheap beer so I want to try to salvage it.

    Thanks.
     
  2. PortLargo

    PortLargo Devotee (473) Oct 19, 2012 Florida

    Tis a predicament . . . my first thoughts are to hold the course. The more active the fermentation the less likely you'll have a problem. On day two of the process you should still have some pretty serious ferm activity going on . . . this is stage 2 or exponential growth phase. The little guys should still be metabolizing the oxygen. Plus, all the O2 that diffused to the headspace would have been mixed with CO2 and pushed out the top.

    I would be suspicious if you are really detecting staleness after only two days of exposure. Raising the temp a couple of degrees should help keep the little yeasties active and happy . . . have to think they would devour any oxygen molecule they ran across.
     
  3. GeeL

    GeeL Aspirant (202) Aug 27, 2008 Massachusetts

    Thanks. It was pretty late on day 2. I brewed it Sun AM and did this Tues at 10 or 11 pm thinking it was Monday.

    It is what it is at this point.
     
  4. MostlyNorwegian

    MostlyNorwegian Zealot (548) Feb 5, 2013 Illinois

    At day two, as already stated. They should still be content chomping away, and the ambient temp should still be a few degrees above actual. Depending on the yeast varietal there should be plenty of work left to do, and it's the more complicated sugars they are working on. You should hopefully still be in that sweet spot where they will reward you for the mistake.
     
  5. MrOH

    MrOH Meyvn (1,069) Jul 5, 2010 Maryland

    What type of beer is it?
     
  6. VikeMan

    VikeMan Poo-Bah (1,884) Jul 12, 2009 Pennsylvania
    Society

    Once the work of converting sugars to ethanol and CO2 begins, the yeast don't need or use much O2. They need it before fermentation begins, to make sterols for cell wall material so that they can divide sufficiently. After that, they will use only a negligible amount of O2.

    There's a pretty good, not too technical, explanation here...
    https://www.morebeer.com/articles/how_yeast_use_oxygen
     
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  7. billandsuz

    billandsuz Devotee (427) Sep 1, 2004 New York
    Industry

    Bad news is that the damage caused by oxidation can not be reversed. All you can hope for is that the yeast uptake some or all of the available oxygen to reduce or eliminate the formation of oxidized compounds. The yeast will not consume the staling compounds once created however.

    So cross your fingers, RDWHAHB and all that. Good luck.
     
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  8. PortLargo

    PortLargo Devotee (473) Oct 19, 2012 Florida

    Do you think the late addition of oxygen will result in a souring effect? In this case would the addition of late yeast (in presence of alcohol) result in more souring? Have you ever considered not aerating your wort if you made a starter with the correct pitch rate?
     
  9. VikeMan

    VikeMan Poo-Bah (1,884) Jul 12, 2009 Pennsylvania
    Society

    I can't think of a reason for it to produce souring. But accelerated staling is a distinct possibility.

    The only time I would consider not aerating (with pure O2) would be if I pitched dry yeast (which comes "pre-loaded" with the building blocks), or when I want to "stress" the yeast, e.g. in a hefeweizen.

    But what exactly do you mean by "correct pitch rate?" Let's look at a fairly common "default" recommended pitch rate for ales: 750,000 Cells/ml/Degree P. When you pitch at that rate, there is still quite a bite of cell growth in the beer wort, and that is why the yeast need O2 to make sterols to make cell walls. Theoretically, you could pitch at a very high rate that would hold cell growth to zero (or close to it). That would be a metric ton of cells, akin to re-pitching onto a yeast cake, except with "all" healthy cells. Pitching that many cells would not only be expensive, but would also tend to produce bland beers, because some yeast derived flavors are produced (or the stage for production is set) during cell growth.
     
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  10. pweis909

    pweis909 Poo-Bah (1,861) Aug 13, 2005 Wisconsin
    Society

    Acetic acid production by bacteria and Brett occurs in the presence of oxygen. Perhaps this is what @PortLargo was thinking. In any event, I didn't read anything in that suggested contamination in addition to oxidation.
     
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  11. PortLargo

    PortLargo Devotee (473) Oct 19, 2012 Florida

    One of the points of your linked article is yeast that can respire alcohol in the presence of oxygen and produce acetic acid (in addition to staleness). Normally not a problem because oxygen is gone before ethanol is produced which is not the case for the OP. The other main point is yeast do not require respiration (oxygen) for budding. It's stated that with an optimal pitch rate (defined as 1 million cells per) no aeration is required, especially high gravity wort when no yeast esters are desired.

    For the OP; If Vikeman is right then it's all over but the crying. If the linked article is correct the tears will be sour(?). When's the first grav check planned?
     
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  12. VikeMan

    VikeMan Poo-Bah (1,884) Jul 12, 2009 Pennsylvania
    Society

    I suspect there's something about the environment in beer that suppresses the phenomenon the article mentions. If O2 caused finished Sacch beers to sour, there would be a whole lot of "Why is my homebrew sour?" posts. One possibility (guess really) off the top of my head is that the ethanol respiration, which only happens in the absence of fermentable sugar, is prevented by the presence of maltotriose, a fermentable sugar. Various yeast strains leave various amounts of it in the finished beer. So maybe its very presence suppresses ethanol respiration.
     
    #12 VikeMan, Mar 28, 2020
    Last edited: Mar 28, 2020
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  13. VikeMan

    VikeMan Poo-Bah (1,884) Jul 12, 2009 Pennsylvania
    Society

    Yeast budding and respiration are two different things. Budding requires sufficient cell wall material. No oxygen means limited cell wall material, thus limited budding (i.e. less "generations" possible). I don't agree with the author's opinion that 1 million cells per ml per degree plato, with no added O2, is somehow optimal, though I'm sure you could "get away with" 1 million cells per ml per degree plato and no forced pure O2 and make OK beer. The author seems to ignore the fact that no beer wort is O2 free to start off.
     
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  14. PortLargo

    PortLargo Devotee (473) Oct 19, 2012 Florida

    Okay @GeeL , it's been a week+ and you've taken a gravity sample by now. Results? Are you getting staleness, sourness, or a peachy-keen flavor? In the interest of Science there's a lot of interest.

    Nor do I. Matter of fact I disagree with most of the author's opinions. Not going to say she's wrong because she used a lot of really big words and I'm a product of pubic schools. But I choose to treat my yeast different that her recommendations.
     
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