Okay, I don't have Yeast in front of me, which probably answers this, but dicussion is always nice... I've never actually oxygenated my wort with pure o2 but have recently decided to give it a try. I know some tests have shown it to be less of a factor as some may think, but I suppose I want to be the judge of that myself. Is there any sort of calculator that works based on gravity, temperature, and volume? I've seen a few different charts that ball park it, which is fine, but none really address those varibles completely, so I'm left scratching my head a bit. For instance, Wyeast just says higher gravity beers may need more time as solubility is lowered, but at what rate? Obviously a 1.080 needs less than a 1.100. They go on to say 60 seconds can get you 12 ppm, but is that only for 5 gallons? Would I double the dosage time for my 11 gallon batches? Would I run it even longer for higher gravity wort? Also, my standard procedure now is to strain into three buckets and than dump them each into my fermentor. It always seemed to have been adequate to make good beer, so I assume it does an okay job at aerating, but when injecting pure o2, should I take this o2 that's already in solution into account? It's an added variable I could probably just ball park, say it is somehwere between 6-8 ppm? Probably overthinking it, just the talk about over-oxygenating worried me. And lastly, how do you guys go about dosing your starters?
I am unaware of a 'calculator' for oxygenating wort. This topic was previously discussed here: https://www.beeradvocate.com/community/threads/oxygenating-wort.94382/ Cheers!
Thanks, Jack. I saw that one, but it didn't really answer my specific questions. I do see Vikeman's excel formula in a subsequently linked post, but he specifically says it's for 5 gallons and I'm not sure I know exactly how to use it. I also see a post that notes levels from Yeast, but they are different from those that Wyeast mentions - https://www.beeradvocate.com/community/threads/oxygenating-wort.94382/#post-1383672 Do you oxygenate with pure o2? How do you go about it? Maybe I'm overthinking the whole thing.
No, I do not use O2. Hopefully some other BA will be able to answer your question concerning a larger (> 5 gallons) batch. Cheers!
Got it, what is your typical method of aeration? Like I said, I've always have fine results with just my straining and dumping. I'm not even sure why I want to try injecting o2, maybe I'll just save it for big beers and starters.
Beers > 1.1 get a 30 second shot from a disposable O2 hardware store bottle with aeration stone setup...don't brew big enough...often enough to warrant anything more elaborate.
Thanks! I have a 1.088 coming up, probably give it a try on that and just err on the side of caution.
There probably isn't a calculator available, there are more variables than listed. I would also assume that when you go from air to pure oxygen you switch from Henry's Law to Raoult's Law. The challenge is knowing what the vapor pressure equilibrium is and what the diffusion coefficient is for the particular wort. Then the time to dissolve will be directly related to the size of the bubbles that your diffusion stone makes, the smaller the bubbles the faster this occurs, and the more volume that these bubbles contact radially the faster this occurs. Experimentation could be done but I would expect that the results will be similar to the observations in various tables with slightly shorter time. The transfer rate in larger volumes will be faster because the concentration gradient stays lower for any given time (assuming that you have excess oxygen). However, you have more volume to saturate. My initial thought considering both would be that the time to saturation will be pretty close for 5 vs 10 gallons. I wouldn't worry about O2 concentration in your starter if you are using a stir plate. I can't speak much to over oxygenation, I only use air and always have good results. If someone knows what the toxic limit of oxygen is to the yeast this may be the best way to determine it. If it is 4x higher than the expected concentration given the tables you probably don't have to worry about it.
I wish I could find the article, (my Google skills have failed!), but the gist of it in my non-scientific talk was that fermentation is an anaerobic process and if your yeast is healthy to begin with, there is no need for oxygenation. The article was compelling enough for me, who owns an O2 tank and aeration stone just for the purpose of making sure my wort is primed and ready for the yeast, to not worry about it anymore and focus on good yeast up front.
From Yeast; When using a flow of 1L/min into 20 L of wort at 75F with a 0.5 micron stone the following is dissolved oxygen levels: 30 secs - 5.1 ppm, 60 secs - 9.2 ppm, 120 secs - 14.0 ppm. For wort > 1.083 they recommend a second dose of oxygen 12 - 18 hours after fermentation begins (after first cell division). I follow these guidelines. I also oxygenate my starters (also recommended by Yeast). Very little effort involved and it seems to help. If I don't forget, sometimes I'll add oxygen mid-way through the starter. A few tips: Oxygen is critical for yeast growth. Shaking/stirring/pumping with air will only get you to ~8 ppm. It's difficult to over-oxygenate . . . the yeast will metabolize it and O2 levels will revert back to atmospheric O2 levels in a few hours (just like CO2 comes out of beer). I have a Type E medical oxygen bottle (820 liters) purchased from a flea market for 20 bucks. It's been used continuously for over three years and pressure shows about 1/3 remaining. I've looked for oxygen calculators but have only found the data from the Yeast authors. As @Elvis_on_Bass says, all of this is quantifiable, but the math would be a real ball-breaker. Vikeman has something about it in his Brewcipher, but I'm not sure what that's based on. I find it easier just to squirt a little too much of the gas.
Thanks for the replies, guys. Appreciate it. Yeah, I've seen one source stating it was as high as 40 ppm. I don't think I would even get close with 60-120 seconds of o2 at 1L/min. I've heard people cite that info before. I think the dessenting view is that fermentation can actually be both anaerobic and aerobic. Maybe this was the article on morebeer.com? How long do you dose it for, like 10 seconds or so?
One could spend $200 or more and get a DO meter to measure the dissolved oxygen. I just use the recommendations that @PortLargo posted.
I don't think I will be going to those lengths. The only reason I pull the triggered on the o2 setup at this point was because I found I had racked up a decent amount of Amazon points
Naw, I give it a full minute . . . don't care if a little is wasted. Oxygen is cheap and the goal is to grow yeast, not make beer. Also, add yeast nutrient.
That is accurate. But before active fermentation takes place the little yeasties adapt to their environment. This is where they really enjoy an oxygen rich environment (aerobic growth), it helps them grow/adapt so they begin their anaerobic process in better shape. So yeast can perform with or without oxygen (they swing both ways), the life-giving gas making them better prepared for their monastic-life without oxygen. Had a girlfriend once that went both ways . . . found out I couldn't match the competition. That's why I tend to over-oxygenate my starters. Not really interested in making beer, the goal being improve yeast health/growth. For a completely different viewpoint, here's a well written article that pretty much de-bunks everything I've said (except part about gf): https://www.morebeer.com/articles/oxygen_in_fermentation
Well that took a turn. That source actually debunks yet at the same time supports what you said, if that makes any sense.
That's the link epk referenced earlier and what I had read some time ago. It's a great article....yeast need O2 for sterol synthesis. I was always looking for a place to use that phrase in a sentence.
https://www.experimentalbrew.com/experiments/writeups/writeup-olive-oil-vs-no-aeration from another BA here...more fun reading
