Maybe you need to look again. I don't own this probe, but most of the probes measure ppm of O2 in solution which can then easily be converted to percent saturation if you know the temperature and atmospheric pressure. If you can achieve say 8 ppm O2 in solution using room air or pure O2, the oxygen concentration is the SAME in both solutions. The saturation is just another way of expressing the oxygen concentration. Hope this helps.
Yes, the probe measures ppm. ppm = parts PER million (denoting concentration.)
Can you easily convert it to percent saturation if you know the temperature and atmospheric pressure? Kind of... but gases aren't all equally soluble, and so according to Henry's Law, you also need to know "Henry's Constant" for the particular gas solute in the particular solvent you're working with (in this case, oxygen in water), which is a bit of a misleading name since it obviously changes depending on the gas and liquid. Thing is though, the only way to find Henry's Constant (other than looking it up, in which case it's really just somebody else who did it for you) is to empirically find it by determining the concentration of the dissolved gas when it's saturated at a given temperature. And they just set that particular concentration of dissolved oxygen to be 100% in order to compare their experimental results in some meaningful way.
The thing is, when you dissolve air, you are dissolving ALL the gases that are in air, not just oxygen. The wort doesn't magically decide to hang on to the oxygen alone, just because it's good for it - do you honestly think other gases are NOT being dissolved? Because if not, that must mean you're instead working on the assumption that a solvent has the capacity for an INFINITE amount of solute, as long as you change the particular solute to a different one once it's saturated - ie, after reaching the saturation point of oxygen, you can then saturate the wort with nitrogen, and then CO2, argon, helium, etc, without causing any of the previous gases to come out of solution - and if that's what you actually think, then you might as well just stop reading this right now; that level of ignorance is incurable.
No, the fact is, a solvent only has a given amount of room. For instance, let's say you're working with a wort temperature and pressure where the saturation point for oxygen alone is 20ppm, and the saturation point of nitrogen is 48ppm (roughly close to accurate), and it's just been boiled so there are absolutely no gases dissolved yet. That doesn't mean you can dissolve 20ppm of oxygen AND 48ppm of nitrogen at the same time. You'd only be able to dissolve the entire 20ppm of oxygen if there is NO nitrogen whatsoever (which I'm sure everyone is well aware is not even close to the reality of ambient air), just like you'd only be able to dissolve the 48ppm of nitrogen if you decided not to include any oxygen. Or you could do a 50-50 mix (10ppm oxygen, 24ppm nitrogen), a 75-25 mix (15ppm oxygen, 12ppm nitrogen), a 25-75 mix (5ppm oxygen, 36ppm nitrogen), or any other combination imaginable.
So, tying back in to the first paragraph as to what gas(es) they used to determine 100% saturation, they did it using AIR, and the saturation point of AIR is where dissolving any more AIR is absolutely impossible. At that point where water becomes saturated with air, the concentration of oxygen is still measurable and should be around 8ppm at fermentation temps. There will also be an unknown amount of nitrogen, CO2, and other atmospheric gases, since they were neither measured nor calculated. But to suggest that these other gases aren't there simply because they weren't measured (since the particular concentrations don't matter for this experiment) is absolutely silly.
However, since these other gases ARE there, taking up a huge proportion of the total dissolved gases that this particular solvent can accommodate, the oxygen is limited to a concentration much lower than it could attain if the other gases were never introduced into the water in the first place - in fact, in typical circumstances it should only be
roughly 20.946% - a mere one-fifth - of the concentration it would be present in if the other gases weren't taking up their fair share (I say "roughly" because the proportion would be slightly changed by the fact that CO2 isn't just a solute but also somewhat reacts with water to form carbonic acid). And so the question becomes, how do you kick all the other gas molecules out, giving oxygen the space to increase in concentration nearly 5-fold? The simple answer, of course, is just to not introduce them in the first place, by using pure oxygen as the solute instead of that mixture of gases we call air.
Need a source for all that? There's actually very little to even source, it's basically a couple of concepts distilled as much as (and in every way) possible, so that one would have to be a troll to keep insisting otherwise, but I suggest you try a high school science/chemistry textbook. I'm not even kidding, I know it's there because I checked - I kept a lot of my old science textbooks since I like hanging on to knowledge and information. I doubt you're going to find much of this (proving, or even arguing against it) in any academic papers because that particular audience is pretty much expected to know such fundamental stuff, not to mention that stuff such as the fact that a solution can contain more of a specific solute when it is the only solute (ie pure oxygen) as opposed to one of many competing solutes (ie air) is pretty much common sense to anyone with even the slightest idea of how solutions work.
Now admittedly, the author doesn't say either way whether the 100% saturation comparator was using the concentration of oxygen in water 100% saturated with air, or 100% saturated with oxygen. But for the reasons stated above - even ignoring the fact that they experimented strictly with methods attempting to saturate the water with air, and not pure O2 - it is just totally impossible for the O2 in water that is mixed with AIR (containing just 21% oxygen) to reach a concentration equal to 95% of the concentration of the oxygen in water saturated entirely with pure O2. That would actually imply that the other 79% of the gas content of air is somehow diminished to a
maximum of 9.1% of total dissolved gases (since nitrogen is about twice as soluble), and that's absolutely absurd. In fact, it even goes on to talk about the risk of yeast toxicity by over-oxygenating when using pure O2, and you'd have to be bizarrely bull-headed to think that when they refer to over-oxygenation, they must be talking about that small margin between the 95% they achieved, and the limit of 100%.
However, if you decide to stick to your nonsensical version of chemistry, that's fine with me. I was far more concerned about the people who might be influenced by your posts to not pursue the quality that they otherwise might have. But I think I've posted more than enough to ensure that the vast majority of open-minded people who might read this thread will know that your claims are bunk, and that they don't even jibe whatsoever with the link you posted thinking it supported those claims. I can't believe I just wasted time writing all this though, because the vast increase in O2 concentrations possible when using pure O2 instead of air is not even close to being a typical point of contention, and because the science behind it is so elementary, it never even has been.
