We’re having a conversation over at The Biergarten regarding yeast and part of that discussion revolves around the use of O2. I hear from a number of brewers that they do not bother with it anymore and that includes Denny. I seem to remember reading that yeast will be starved for O2 at various points and that a blast of O2 is very helpful to the yeast. I add O2 when I make a starter and every time I pitch whether the yeast is dry, liquid, first run, harvested, etc. I realize things change and what was thought to be gospel 10-20 years ago may not be now. Maybe Saccharomyces will join in here and shine some light. Let’s have a show of hands… who uses it and who has abandoned it? Cheers Beerheads.
I pitch yeast as my fermenter is filling.
As a small batch brewer (3gal into fermenter) I don’t worry about oxygenating my wort regardless of whether I’m using dry or liquid yeast. Not saying this is proper procedure and not saying I wouldn’t get better results if I bought a DO meter and measured 8ppm or whatever. I do give the fermenter a good, hard swirl after it’s filled, thinking that this helps everything harmonize…and I’m sure this adds a bit of O2.
Not sure if I would pay more attention to O2 if I were brewing bigger batches. Probably would, but I’m never brewing bigger batches. 
Not very helpful, I know.
I use dry yeast straight from the package and do not use O2. As the fermenter is filling I pitch the yeast so the turbulence from filling mixes the yeast into the wort.
I use O2 when pitching a liquid culture or a harvested slurry. I don’t use O2 on the first pitch of dry yeast.
I use dry yeast 90% of the time lately so I rarely use O2 anymore.
I would also be curious about the scientific findings of O2’s impact on the yeast and final beer and also if brewers who choose not to use O2 just prefer not to buy the O2 stone, the bottles of O2, etc. I use pure O2 from a cannister sent through a sanitized stone for about 20-30 seconds. I also pitch the yeast as the wort is falling into the fermenter so there should be some O2 there but I have always wondered if that’s enough. If there was science that said that yeast get plenty of O2 without using pure O2, I would certainly consider discontinuing it.
I started oxygenating with my liquid pitches ~10 yrs ago. It had a huge impact on my beers’ quality. I wouldn’t think of pitching liquid yeast without giving the wort a blast of oxygen. YMMV. It’s totally unnecessary with dry yeast.
Make sure you understand what the yeast use the O2 for. There are a lot of misconceptions about this. It’s about fortifying cell membranes to withstand the osmotic pressure, it’s not about replication. There’s a lot of info on this thread forum about that, and the latest Zymurgy talked about it in their mythbuster series.
I do the same with dry yeast, pitch while the fermenter is filling. I fill from the top and have a copper tube on the end of the transfer hose with a ton of holes drilled in it. I stop filling about halfway, pitch the dry yeast and finish filling. This mixes the yeast and the wort well. Although dry yeast does not need O2 because of the sterols the yeast has built up during the production process, the copper tube adds some O2 to the wort which IMHO doesn’t hurt.
When using liquid yeast, I always add O2 by the same method described above. With big beers that I brew with a friend, we normally add some pure O2 to the wort with a carbonation stone.
Do O2 requirements vary based on:
Ale or lager yeast?
Dry or Liquid
Wort composition
Wort Gravity
Wort Volume
Fermenter size/shape
Fermentation temperature
Pitch Rate
Yeast generation
etc…
Or are O2 requirements the same, no matter what?
This^^^
Studies on yeast and oxygen are numerous. They all come to the same conclusion. Liquid yeast needs oxygen, it’s not ever debated except among home brewers. It needs it to synthesize lipids for replication (cell membrane) and for producing sterols as well. I have talk to some homebrewers who stop using oxygen and have no ill effects, but then ask why there is an off flavor in the beer. I started aerating 12 years ago and the difference was tremendous, so much so that I would not brew without it. I enter a lot of competitions and I can’t imagine I would win much without proper aeration, it’s that fundamental. This is especially true for lagers. Some strains need more oxygen than others, but for the most part, lager yeast benefits from 12-15ppm of dissolved oxygen at pitch. The only way to reach that level is with pure oxygen through a diffusion stone.
Dry yeast on the other hand already has lipid and sterol reserves, so aerating at pitch is not necessary (unless they have been through a starter or are being repitched), but also not harmful.
This is good stuff guys. I primarily use liquid yeast although I am currently at the end of a run with S-04. I also make far more lagers than ales so it might be that I have found the use of O2 to be important because of that… mainly liquid yeast and probably 75% lager production throughout the year. I suppose it’s all about “you do you” but with so many brewers saying that they stopped using O2 (and they DID NOT specify that they do this because they primarily use dry yeast), I was scratching my head about whether it was still relevant. For me it is… fundamental, apparently.
yes to all i imagine. (except im not sure about wort volume, unless its volume in relation to starter size? ie. starter size stays the same but wort increases?)
if i used liquid yeast to ferment high gravity beers i would want to use O2 imho. my MO is to just use 2 or more dry yeast packets for gravities over 1.065. yes its a weakspot in my brewing. oh well.
Reality often astonishes theory. I used O2 for quite a while. Then I tried some batches without it and saw no difference in my liquid yeast batches. Gave my O2 setup away. I know and understand the science, but I trust my own experience also. I advise everyone to do the same.
lol, maybe someone can give it away… to me…
i had a bad experience i attributed to insufficient oxygen, though it could have been the grist. but i believe in o2 for now
I hear you and I have tattooed your saying “reality often astonishes theory” on a part of my body that I would rather not discuss at the moment. :D There are a lot of variables here. I have sat down with brewers who were SO enthusiastic about their beers and when I tasted them… well, I was far less enthusiastic. Earlier in this thread someone mentioned a brewer saying that had stopped doing this or that with no ill-effects. That is… no ill-effects as far as the brewer was concerned. I try to compare my beers with commercial beers to try to get the best perspective. There are times when I would rather drink my own beers but perfection on some styles has eluded me so I might buy commercial examples of that style and continue my push towards a satisfactory homebrewed version of that beer. Denny, you have a lot of brewing and beer experience and if you say that you can skip oxygenation with no ill-effects then I believe it.
Ken, I don’t want you to believe me. I want you to believe yourself. Try it. Make your own decision the way I did.
I’m sure no one here doubts the need for proper oxygenation, I just don’t think there is any consensus on the definition of “proper”.
Is there a particular ppm that needs to be met? For every single brewing situation? Maybe, but I’d find it hard to believe.
Feels like a Mug’s game.
For a good long time, most of us went by recommendations that suggested 8-12 ppm, the lower end really about all you can achieve through shaking a heavy fermenter. If I recall, the Yeast book pushed 12 ppm, and recommended a shot of pure O2. B &Q’s book on Yeast and Fermentation also recommends 12 ppm, but then go through to prove that it varies, and generally in ways that are beyond a normal homebrewer’s capability. The recommendations for a starter apply to most liquid yeast vials/packs, when repitching yeast (including formerly dry yeast).
A couple of things also to consider here:
- Shaken and Not Stirred starters or even so-called Vitality starters are not considered in any of the academic books. It would be nice if one of the big yeast manufacturers would take this up and give some solid lab results.
- If we are claiming O2 uptake is much higher surface ratios because of the homebrew scale - it feels like this should also be applied to our fermentation transfers. I haven’t done the math - don’t plan to. I imagine we are getting, generally, adequate oxidation for a medium gravity beer in most cases just by a splashy transfer.
- Compared to when I used to get pretty marginal yeast nearly 20 years ago to today, the bar has moved quite a bit. New processes seem to be yielding a more stable delivery of healthy yeast.
- I am a weirdo that from my mead/wine practices uses GoFerm and rehydrates yeast before pitching - and I get consistent results. I do SnS with liquid yeast pitches and only now use pure O2 if my gravity is above 1.065, and only then a day or two into fermentation to keep things going. I know some dry yeast manufacturers now just recommend pitching dry. I just want to make sure that packet is viable.
Note that Denny is now using SNS starters. That process gives the yeast oxygen before pitching it into the beer. Is it enough oxygen? The inventor of the SNS method says yes, but I am not convinced. I think that some kind of aeration during the transfer from kettle to fermenter is still worthwhile. I have a wine-type aerator that I put on the end of my transfer hose. I no longer use oxygen except for very high gravity beers.
Are you not convinced due to your experience?
I feel like lab results are uneccessary if you have your own results to examine. After all, that’s what matters to me.