I had possession of a decent DO meter about a decade ago and did a few experiments while I had it. One was seeing how fast the O2 was removed from strike liquor using bakers yeast with a bit of corn sugar; the other was seeing how fast the O2 I added to a carboy of freshly pitched wort disappeared. In both cases there was very little O2 remaining after 6 hours, and within 12 hours there was no measurable O2 remaining (I was actually pretty impressed with the strike water deaeration thing)...
Cheers!
This is an interesting data point, however I would point out that in the example using wort, you do not technically know what amount of that oxygen is being taken up and used by the yeast as opposed to reacting with the wort. One of the fundamental frustrations I'm sure that all of us in this thread have when discussing a topic like this, is that we do not have access to instrumentation that would allow us to quantify nonenal (from oxidation of unsaturated fatty acids from malt) or hop aroma compounds like linalool that can be oxidized, in the final beer to determine to what degree
oxygenation of the main body of wort is actually
oxidizing the wort.
To me, this idea seems sensible: yeast need oxygen to reproduce. Once there's enough yeast cells, no more need, I guess. Anaerobic respiration thereafter.
In other words start with enough cells somehow, and skip aeration/oxygenation.
I'm not seeing this as a revolutionary change. The main idea: do any needed cell reproduction outside the main body of wort, which never gets aerated/oxygenated cuz there's no need and it might be a bad thing. Cool.
This is my exact general feeling on the totality of the topic. A healthy fermentation requires a certain minimum population and the data in the original study supports this idea where oxygenating more than a certain amount didn't yield further benefits.
I believe the purpose of the historical practice of adding oxygen to the wort is that it gives you a free and significant boost in yeast cell count. If I was a commercial brewery needing 4 bricks of US-05 to ferment a batch, and could get away with pitching two and adding oxygen instead, that's a no-brainer. You're using the free raw materials floating around in your wort and a few bucks worth of gas to make more yeast.
Now on the homebrew scale, the cost of yeast is not as big a factor, and as well our homebrew pitches these days are bigger and healthier
on average than they used to be (caveats in my next point), and we almost always have access to the small amounts of wort we require to make starters. So then it just becomes a question of best practice where I'm with Bobby that pitching a healthy and active population of yeast must have some quantifiable benefit even if it would of course fail a Brulosophy triangle test.
One pack is often not enough for high gravity ales or normal to high gravity lagers and if it is enough to get the job done, it may not ferment as clean as it would with more. Clean isn't always the goal, but just sayin.
I know that you know, better than me, that
there is still tremendous variability in what "one pack" means, but here are some highlights from the last 25 batches I brewed in the past 6 months:
- I direct pitched an expired Omega Witbier pack from Brew Hardware that took off within 20 hours and showed all signs of an extremely healthy fermentation
- I direct pitched two full dry yeast sachets of Lallemand WLP860 expiration Oct2025 obtained from the late Atlantic Brew Supply and absolutely nothing happened. After 6 days I krausened a liter off the top of a 34/70 batch that was fermenting. Within 12 hours that took off but showed all signs during fermentation that it was an underpitch as it took FOREVER to ferment.
- I used a fresh pitch of Wyeast 1099 from ABS. The smack pack never inflated and the fermentation was slow to start and slow to finish.
- I brewed multiple 1.045ish lagers using a single sachet of either 34/70 or S-189 and every single beer fermented out in about 7-9 days, no esters, fusels, or diacetyl.
- Every single starter I pitched, regardless of how much yeast I started with, took off within 12-24 hours, and showed all signs of a healthy fermentation - I make 1 Liter starters and shake vigorously every hour or two to encourage oxygenation and replication.
I learned my lesson. The only way to ensure you have enough yeast, and healthy yeast, is to rehydrate or make a starter and monitor the activity.
I still have never oxygenated a single batch beyond what I pick up while chilling and transferring. I cannot say that this is good/bad or right/wrong. I never discourage other brewers from oxygenating unless it's an ester-driven style of beer. However, in years past I've made some very fruity/esterey ales and lagers where it was not desired. Now my beers are more or less all clean when I want them to be, and it's purely a combination of pitching more and controlling temperature better than I used to.