I think you are making a very big leap from volume to mass, and you are assuming that somehow they are related, but only in the way that best suits your observation. But then after that you are disconnecting the mass from the volume when it is no longer convenient for them to be related… If 20% of the gas is oxygen, then 20% of the airspace in there is oxygen. If it dissolves into the liquid, 20% of the space is now a vacuum. It’s really some pretty basic physics, there is no free lunch.
No, I actually looked up the mass of the oxygen at STP for a volume of 20% of 3 liters. The oxygen does not all dissolve into the liquid, but saturates at somewhere around 10 ppm (10 mg/liter). I did get that wrong and say micrograms instead of milligrams. Even so, if 10 mg of the 1 gram of oxygen in the headspace dissolves into the liquid it is a 1% effect, not enough to pull a noticeable vacuum. I am not trying to pick a fight, but if you can clearly explain where I have gone wrong I would like to hear it.
Many years ago, middle school physics, we did an experiment. Pans of water, 3 flasks roughly 3-4" dia, wire racks to support the flasks. Flasks had very small long stems, say 1/8" ID x 1.5-2" long. Put a little salt in the water to make it electrically conductive. Filled the flasks 100% full with water and turned them upside down over the pan of water so the stems were submerged, no water can escape.
Took 2 pieces of romex wire, stripped a small amount of the ends and bent it to hook below and up into the stems of the flasks (2 of them). Hook the other ends to a battery charger (dc supply) and wait. Bubbles form as electrolysis separates the H from the O at a rate of 2:1. Flask 1 is 100% full of H when flask 2 is 50% full of O. Swap out flask 1 with flask 3 and continue. When flask 3 is 100% full, flask 2 is also 100% full. Now there’s 2 flasks of hydrogen and one of oxygen. We now know why they call it H2O. 2 parts H to 1 part O. Ok, cool enough.
Now the teacher lights a match and puts it to flask 1 and poof, Hindenburg example. Great, learned that’s flammable. Wonderful. Now to show how gas dissolves into liquid, takes the O flask with finger covering the opening and places it on another wire rack in a new pan of water. I do not recall the new pan being treated, boiled, any of that. I think it was just clean water. Very slowly, water begins moving up the stem to the globe portion of the flask. It has a minuscule amount of surface area so this takes a few seconds, but only a few. Guessing here, say 4-6 seconds. Once the water reaches the globe of the flask, obviously the surface area increases dramatically. Immediately there’s acceleration of the rate the O dissolves. The inrush very quickly increases to where it looks like a fire hose filling the flask, and in the span of maybe 3 seconds, it’s 100% full of water with not so much as an atom of gas remaining in the flask. The vacuum formed was absolute as best as we could tell. I would fear doing this experiment again using a flask that wasn’t a sphere, that it might implode the glass if the shape wasn’t conducive to handling 30 inches of vacuum.
The oxygen vanished instantly into the water that wasn’t already saturated. The wort we are dealing with which has been boiled, is devoid of DO. So it is basically the canary in the coal mine with respect to the affinity for oxygen uptake, it’s massively thirsty. That’s the reason when we use an O stone in wort, bubbles don’t even approach the surface of the wort for 1-1.5 seconds after the gas is turned on. The very first stuff dissolves instantly, till at least some wort has enough DO to allow other bubbles to rise to the surface through the stuff which is no longer 0% DO… If you ferment in glass and inject O, you can see this happen when you place the stone right next to the glass where its visible. Watch closely and the initial bubbles will not come anywhere near the surface. Later, you get foam forming from all the excess. If you stir the stone around, it will take considerably longer before any substantial bubbles reach the surface, then near all of em will. The dissolving slows quickly.
Volume is volume. IF oxygen is being dissolved, something must displace it. No displacement = nothing dissolved. Either we begin to pull a vacuum and star san enters my hypothetical hose, or the container collapses some, or nothing is happening. But we must pick one.
Dump some beer on a plate and taste it, it’s oxidized instantly. Doesn’t need shaken the life out of it, it loves oxygen, at least till it doesn’t. And I’m not trying to say sns doesn’t work. I’m simply saying the assumptions about O uptake are flawed.
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I agree with you in principle, but I am saying that in practice the numbers are so small the effect is insignificant. Here is a blog from White Labs, where they know a thing or two about wort oxygenation. It says that the maximum solubility of oxygen into wort from air is 9.5 ppm. From pure oxygen it is 40 ppm.
I’m not scientific. I have respect for those of you who dive deep into things like this because we all benefit from it. I have made stir-plate starters for years and lately I have made 4, 5, 6 SNS starters with lager yeast. I shake the vessel and get a good amount of foam but it seems like all the shaking in the world will still only produce “so much” foam. I pitch. I believe I have also sent my sanitized O2 stone into the vessel because I believe that giving fresh yeast O2 seems beneficial. My stir-plate starters started pretty quickly. I feel like my SNS starters start slower although there must be a lot of variables here including yeast health. The resulting beers don’t seem any different between the two processes. I will be making a starter coming up here in about a month or so. I’ll probably do the SNS + SHAKE + PURE O2 method again but I am not seeing anything VERY different between the two processes. A stir-plate starter spins … the SNS starter gets the occasional shake or swirl. They both work. The beer is no different, IMO.
I agree. I see no benefit to the yeast with SNS over a stir plate. There is nothing special that is accomplished with the SNS that a stir plate won’t do. I prefer a stir plate, I can start the yeast, go to bed and wake up to a starter in full krausen.
Whether you use a stir plate or SNS, the exchange of gases is key, get rid of co2, introduce small amounts of oxygen. Both will increase yeast counts and health. I think both are very important, but push comes to shove, yeast health tops yeast cell counts.
I’ve seen those stated numbers, but I seem to recall 9 and 20 thrown around. Maybe it’s 40, I never really cared enough to delve into that. Either number is ok with me for my beer. 
Something seems wrong with these stated volume vs mass numbers though. The flasks we used in school were roughly 1/2 a L. This was late 70s or maybe 1980, so it’s been a long time and I more recall the profound parts, not so much the details. But I recall having them in my hands, and they were large enough hold a good bit of water. Idk if flasks were metric then. But 1/2L is close enough.
There’d be several variables in our experiment. How quickly does the dissolved oxygen move into liquid that isn’t yet saturated? My observation was the liquid was entering the flask at about 2 zillion mph. Seriously, that was the impressive part was seeing the incredible speed at which that flask filled. Then also, that the flask was totally full when finished. I distinctly recall there not being a single bubble left. At that speed, and with such a small opening for the liquid to enter through, one would think the only liquid receiving any of that oxygen was what went in the flask. But, I don’t know what speeds things move at an atomic level.
Next variable, how much water was in the pan? Well, that was a pretty good bit of water. I’d say the water was 2 to 2-1/2 inches deep, and understand here this was decades ago, but I recall the pans as at least a foot front to back and oblong, longer in width. So, quite a large volume of water.
The number which makes the least sense to me is the 6 cc of volume into a L of liquid. No matter how I view this, our experiment absolutely exceeded that. Even if that’s reflective of what we’re seeing, that’s a lot of distance in a 1/4" ID tube. So there should be a good bit of liquid pulled in my hypothetical tube regardless of how little oxygen gets dissolved. No matter what, the amount is non-zero. And even if we use 1L liquid, and 1/4" ID tubing, 6 cc of oxygen = not quite 8" of tubing volume.
The next part that is quite unintuitive is to know that 1L of water will dissolve a trainload of sugar, but supposedly almost no oxygen. If 6 cc of Oxygen is all that will dissolve, that amounts to 1.217 teaspoons of gas. Saturation at 40cc = 2.71 Tablespoons of gas. Absolutely none of this reflects what I saw all those years ago. I don’t know what’s missing, but something has to be.
The claims are twofold. 1, it’s easier and requires less gear. 2, some seem to think the stir bar is acting like a blender and damaging the yeast. May or may not be true, I do not know and make no claim either way. I do know I made my own stir plate and use a 2" stir bar at a very slow speed. So mine is considerably slower than other types commercially available. I’ve continued using mine only because I really don’t have an ideal container to try the SNS way.
It’s interesting that people jump through incredible hoops of fire to keep oxygen away from their finished beer. Some claim that so much as opening a fermenter to do anything causes oxygen ingress. Yet when they want some in there, one must shake the life out of it to get anything at all. Lol. Which is it?
Both are correct. You need to look at the numbers. For yeast health the goal is something like 10 parts per million of dissolved oxygen, and it is hard to get that much. For packaged beer the goal is to keep the dissolved oxygen below something like 40 parts per BILLION, or hundreds of times less. It is easy to get that level of dissolved oxygen into finished beer if you aren’t careful.
But the part that makes me rub my chin is that in the original SNS starter thread there was technical information about how a stirplate is NOT the way to make a starter because of (technical stuff) and I started out a little confused because I have had great success with my stirplate and made great beers from the yeast that was grown on the stirplate. I know the person who came up with the process and posted the information knows A LOT more about yeast growth, health, etc. than I do but the information in that thread seemed positively breathless about how one should not use a stirplate but SNS instead and the fact that I’m not overly impressed leaves me … well … unimpressed.
Apples and oranges on the oxygen thing. Not to mention that I think people are way too paranoid about O2. Having done the stir plate thing for many years, for ME SNS is faster and easier. My impression is that I get better results. Everyone should do whatever the hell they want to.
IIRC, the thread on the SNS starter was less about “being easier” and more about “this is the proper way to do it” as if a stirplate was inferior and damaging to the yeast (cell shear or something?). Do I remember that correctly? I agree everyone should use the process they prefer but when I hear someone with some deep knowledge on a topic (especially yeast), I tend to listen. I seem to remember the thread being more of a “do this, not that” … not “here’s another way to do it that’s easier!” kind of thing.
It was as much, if not more, about the starter wort not being as oxidized. Also faster if you’re one who crashes and decant. Easier is my own observation.
I recall the same thing you do, that it was not about just an easier way but Superior as well. And the one thing I specifically took note of was the stir plate damaging the yeast mechanically. I’m paraphrasing there but you know what I mean. I just happened to have a really slow stir plate so I feel mine is perfectly fine.
Denny, I agree with you completely, whatever is simple and works, believe me I’m all for it. As I said, I would try it but I just don’t feel like buying a container for that right at this minute, especially when I’m winding down on brewing for the next couple of months. I have an awful lot of beer in stock. And I just spent $1150 on brewing equipment over the weekend. LOL
Yes, the original author was very strongly opinionated on the subject and quite sure that his way was the only way. I am skeptical that the yeast are that fragile. I do SNS usually because it is simpler, and I think pitching active yeast rather than dormant yeast is good.
Well, one could pitch active yeast from an SNS starter or a stirplate starter for sure. I guess I am generally open-minded about things like this because if something is going to make better beer, I’m there. But if I don’t find the value in it I will mention it … maybe not to pour cold water on it but maybe to ask if I’m missing something, etc. In this particular case, the SNS starter (to me) seemed like a solution looking for a problem. I was already having good success with stirplate starters.
Exactly.
Without opening, I think it’s the first link is the one I found when you mentioned this to me. I don’t think I’ve seen the second one. I’ll have to check that out. I read a very large thread here also.
I must have glossed over the parts about oxidizing the starter wort, that didn’t resonate with me. I would figure if we inject oxygen into our batch and it will clean it up before things are done, that more oxygen in the starter is irrelevant. But that’s just my off the cuff observation. I’ve seen discussions about oxygen in the mash changing the maltiness of finished beers, but I again don’t understand why that matters if we’re going to take an oxygen stone and force it into the wort in the fermenter. Doesn’t that do the same thing? I know, different stages different results. But when I hear that some procedure makes something better, I like to be able to observe the difference in my own situation. If I can’t say that I see a difference, I either store the information away or outright forget it, and choose the method that suits me best.
To me, I feel the biggest advantage of SNS is that you can save the money on a stir plate and the associated trinkets, which can definitely add up. But that ship has sailed for me so that’s out of the equation now. And I built my own for under $10 so cost wasn’t really a factor. The flask cost way more.
How many years did everyone utilize starter calculators in the various software or on websites, only to be told yeast count is secondary? I personally dismissed them out of hand because I felt they were complete marketing horse%&#@* to get people to buy more yeast. When you look at the math of those things, you do a second generation starter and you gain virtually nothing. And there’s diminishing returns the farther you go. Stick your batch volume into the calculator as the fourth stage and it’ll say almost nothing happens. Moral of the story? You’ve got to buy more yeast! Only the store-bought stuff replicates! I guess the yeasties must say, no you cheap bastard, we are only going to go so far and that’s it! Makes you wonder how the yeast manufacturers can talk them into replicating so they have more to sell.
I take an awful lot of stuff I hear with a grain of salt.
Here are some earlier postings from Mark VanDitta (AKA YeastWhisperer, AKA S. Cerevisiae)…
Unlike some here I did not read into them any claims of superiority in these articles.
https://www.jimsbeerkit.co.uk/forum/viewtopic.php?f=12&t=70926&sid=fecdbc5aa2ef3406434a2a2f6ff3e64c
Taken from the first link Denny supplied above:
[quote]People claim that spinning the bar fast enough to create a vortex improves oxygenation. To a point, that claim is true because it results in an increase in specific surface area. However, doing so comes at a cost to yeast cell wall health due to shear stress caused by the spinning bar (i.e., the spinning bar is a source of friction for the yeast cells in a starter). Shear stress is something that has been well studied when it comes to the production of dry yeast.
[/quote]
I think it was the threads here where people saw the claims that a stir plate was simply bad. I only read these years after they’d died out, but the message was there. It’s entirely possible the stir plate does ‘bludgeon’ the yeast to a point of being knocked out, I don’t know. Maybe that’s why when I see videos in a commercial brewery lab they have 16 flasks sitting on a gizmo that swirls them around in circles to keep them moving. But, that also leads me to believe that agitation is a good thing, not bad. I chose to do the easy solution which was to build a stir plate with a large bar which spins slowly. I can make a tornado if I want, I just don’t.
Possible Correction Here:
I’m not a chemist, so there is that. But from reading I did this morning, it does appear that my experiment I relayed above does indeed differ from atmospheric conditions in a substantial way. This is just conjecture at this point, but what I am thinking is that my 3 flasks in the experiment above were full of H and O just precisely as wrote it. However, what is being discussed in this SNS and Brewing context is NOT O, but O2. Someone please correct me if I have that wrong. Both are called “Oxygen”, but they are NOT the same thing. Now, I’m under the impression that what I buy in the red tanks and for my Acetylene torch is O. So when I inject my beer, I’m putting in O, not O2. Perhaps there’s some O2 in there also, hard to say. I say the O I buy is the highly reactive type O. Hence the reason it dissolved completely. Anyone more knowledgeable care to expand on that?