Homebrew Beer Blog

Mar 22

Fermenter Yeast Growth and High O2

Brewing, Oxygen Topics Add comments

An observation today... The test batch that was saturated with O2 (left) has significantly more yeast than the controlled O2 batch. All that yeast growth is great for making yeast, but I don't think it's so great for making beer...

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5 comments

1. § Michael Sweeney said on : 03/24/08 @ 13:13
   Why would it not be great for making beer? Sure to a certain extent too much yeast is a bad thing. But on the other hand more yeast means healthier yeast, which also means a cleaner fermentation.
2. § Mike Flaminio® said on : 03/24/08 @ 13:44
   Michael,
   
   I think there needs to be a differentiation between pitch rate (growth in the starter) and growth in the fermenter. In the previous Dissolved O2 post I cited a couple sources indicating that excessive yeast growth in the fermenter isn't desirable (Lewis/Young, Brewing), (Fix, Analysis of Brewing Techniques).
   
   Generally, we want no more than 3-4 cell divisions for fermentation (M.B. Raines). If there is O2 present, the yeast will continue to propagate. So, if we're pitching an approximate ideal rate for that 3-4 fold growth, it would seem we want to match the O2 requirements to not only support that growth, but also not to exceed it.
   
   I was thinking of doing another test with three jugs. One with no O2, one with 10 ppm, and one saturated, then compare. That may illustrate the difference in growth between oxygen levels.
   
   I invite everyone to do some split batch experiments and see if any of this manifests in the glass.
   
   
3. § Michael Sweeney said on : 03/24/08 @ 13:55
   I'll admit, you've obviously have done your homework and you've got me completely outmatched as far as knowledge goes. But you've also got my complete attention. I'll make sure to keep watching your progress.
4. § Mike Flaminio® said on : 04/22/09 @ 10:05
   Depends on the yeast you're using. Cold and time will settle out any yeast, but some take longer than others. It's likely not an issue of pitching too much.
   
   Usually what I do, is I'll rack to a keg, chill the keg down to close to freezing, then do a gelatin treatment. Isinglass work even better, but I just use gel since it's cheap and I buy it at the store. Then I leave it a few days, and rack to a serving keg. All the yeast has settled out. Good luck!
5. § sue Hayward said on : 04/22/09 @ 09:07
   
   As you seem to be techically minded on this subject, can I just ask, in simple terms, if I have pitched too much yeast for batch (cloudy, and when I test a glass with isinglass I get way too much sediment at the bottom!) what's best to do before a rack it? Move to holding tank, then rack, prime and isinglass after? Or straight to racking? Help! Have got fermenter down to 8 degrees and to help yeast drop out, fermentation has stopped, FG 1009 OG 1039 I want to bottle and cask but it's still cloudy and I don't want to end up with half a bottle of sediment! Isinglass clears it but leaves a lot of sediment at the bottom of test glass, any suggestions?

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