The definitive aeration/oxygenation experiment

[Kaiser]

Good job, and great idea whith the gloves.

Safale S-04 is claimed to attenuate in the low 70's so the O2 injected batch is nearly done.

Since you don't know the composition of the wort and fermentation conditions when they measured atteniuation for the yeast, you won't really know where your batches will finish.

Kai

 

[Bobby_M]

Right on Kaiser, I realize that estimated attenuation figures are bull until they're measured.

 

[clayof2day]

Also, 1018 and 1019 are pretty darn close. If we really wanted to be accurate, each method (1,2, and 3) would have to be done in triplicate and the average gravities taken at each timepoint. This is not to take anything away from your experiment, however, I think it was great to watch and very informative. I'm just saying, with all the variables that could be present in pitch rate, volume measurement, etc. I would have to say that at this point 1018 and 1019 probably aren't statistically significant in their difference. The other thing to consider is that 2 minutes of shaking isn't very much. Air is only about 20% oxygen and depending on how the carboy was shaken it may not have maximized the surface area to volume ratio of the wort and thus affected the solubility of gasses in the wort. Remeber the O2 had a diffusion stone. #2 did take off first though, indicating that the had indeed done something.

I'm excited to see the FG numbers, great work!

 

[Kaiser]

Right on Kaiser, I realize that estimated attenuation figures are bull until they're measured.

I didn't want to be a smart-ass, but some brewers do take these attenuation numbers way to seriously.

Kai

 

[Pumbaa]

IMHO I would expect #2 to start "off gassing" as you put it first because of the amount of gas that was not disolved but instead suspended in the wort.

When I am cleaning my carboys (or even rinsing them out) I cover the opening with my hand and shake the hell out of them and get a pretty decent presure release. Depending on the size of your airstone (mine is 2 microns) I would expect those bubles to be disolved more and faster then just shaking.

Still interesting, nice work

 

[ColoradoXJ13]

I really see no difference in your numbers, although I respect you for the effort put into this experiment. I have been seeing a lot of non-scientific stuff on this board, a lot of speculation, and a lot of opinions that are unfoundd. A difference of .003 is really nothing in the large sense of things (n=1, standard deviations, etc), and as clayof2day said, you need to repeat this experiment a bunch of times...

Personally, as far as my 'brewery' goes, I am going to try to spend as little money and keep it as simple as possible, and this includes pitching and shaking. But then again, boys love their toys, I drive a jeep with well over $5000 in modifications that are totally not necessary...to each their own.

That being said, I am not even close to hitting most attenuation numbers, i think the LME from my shop sucks, but I am still going to bottle it when SG's are steady and bottles will not explode.

 

[RichBrewer]

That being said, I am not even close to hitting most attenuation numbers, i think the LME from my shop sucks, but I am still going to bottle it when SG's are steady and bottles will not explode.

What LHBS do you shop at for your LME? Have you tried DME?

 

[Bobby_M]

First, I want to say that constructive criticisms are welcome, expecially in the methods so that the next brewer to take this on can be more accurate. However, I don't want anyone slamming my results unless they're willing to disprove them with their own test. It's easy to talk about variables and controls all day long than it is to put it into practice especially when my last experience with scientific method was 14 years ago in high school. That being said, here are some more comments.

clay said: I'm just saying, with all the variables that could be present in pitch rate, volume measurement, etc. I would have to say that at this point 1018 and 1019 probably aren't statistically significant in their difference. The other thing to consider is that 2 minutes of shaking isn't very much. Air is only about 20% oxygen and depending on how the carboy was shaken it may not have maximized the surface area to volume ratio of the wort and thus affected the solubility of gasses in the wort. Remeber the O2 had a diffusion stone. #2 did take off first though, indicating that the had indeed done something.

Agreed. I said above that I really can't be positive that #1 & #2 are different enough to make any claims. In fact, to take any possible bias away, it would be nice for the gravity tester to not know which sample was which. I personally can't imagine I would WANT any particular result except to confirm that using my O2 system is useful. However, I didn't pay for my O2 bottle so I really have no vested interest. Still, bad science abound.

If shaking was my usual method, there's no way I'd do it for more than 2 minutes. Besides, in a typical 5 gallon batch, you'd never be able to shake with the same vigor as I did on this one gallon bottle. There was only foam, almost no liquid wort could be seen at the bottom. I believe I got all the air from the headspace pretty well in contact with the wort in that container.

To your last comment about #2 taking off first, it says nothing about the benefit of aeration though. As we discussed earlier, taking off first suggests that the reproductive cycle simply didn't happen or didn't last very long.

 

[Bobby_M]

IMHO I would expect #2 to start "off gassing" as you put it first because of the amount of gas that was not disolved but instead suspended in the wort.

I used the term off gassing but I really meant fermenting. Any gas that was in the container prior to shaking was just redistributed (suspended). It's not the same as if I compressed the gas first. If this is your aeration method you really just hope that some of the O2 in that air dissolves into the wort. I'm not sure I'm saying it right but I don't think the inition pressure build up you see on #2 has anything to do with suspended air coming out of solution. I believe it is CO2 being created via fermentation.

When I am cleaning my carboys (or even rinsing them out) I cover the opening with my hand and shake the hell out of them and get a pretty decent presure release.

I'm taking a guess, but I think that has a lot more to do with the temperature of the water. Try it this way, heat up the carboy with warm water. Then put cold water in and shake it up. I bet you get a vacuum on your hand.

Depending on the size of your airstone (mine is 2 microns) I would expect those bubles to be disolved more and faster then just shaking.

Yeah, who knows. It's too bad I don't have a pump/airstone. I THINK it's about the same as shaking in how much O2 you end up with. The real benefit to airpump systems is the ability to filter the air which you can't do with the shake method. No matter how small the risk, the shake method takes possibly contaminated air from the headspace and completely distributes it throughout your wort.

 

[D*Bo]

You're also supposed to get beter results (more o2 absorption) by having the o2 bubbles barely break the surface. By having a lower pressure and smaller bubbles, they stay in contact with the liquid longer allowing more to be absorbed. Also the vigorus bubbling at the surface knocks gas out of solution lowering the total disolved gasses.

 

[Bobby_M]

I really see no difference in your numbers, although I respect you for the effort put into this experiment... A difference of .003 is really nothing in the large sense of things...

I agree on sample #1 and 2 being nearly identical, but my current conclusion is that #3 was the stronger ferment at 43 hours. Depending on your hydrometer, the scale can be such that 1.019 to 1.016 is about 3/8ths of an inch.

...I have been seeing a lot of non-scientific stuff on this board, a lot of speculation, and a lot of opinions that are unfoundd. ...and as clayof2day said, you need to repeat this experiment a bunch of times...

I agree with the first point in that a lot of people take what they hear or read a little too seriously. I was hoping to give a little more validity to some of the claims and take away from others by doing this simple test. I may repeat the test myself using better methods and just for the sake of repeatability and confirmation of results but it would be a better if others try the same experiment (confirmation of peers and all).

Personally, as far as my 'brewery' goes, I am going to try to spend as little money and keep it as simple as possible, and this includes pitching and shaking. But then again, boys love their toys, I drive a jeep with well over $5000 in modifications that are totally not necessary...to each their own.

That being said, I am not even close to hitting most attenuation numbers, i think the LME from my shop sucks, but I am still going to bottle it when SG's are steady and bottles will not explode.

I think we all want to keep it reasonably cheap and simple, but we all want to improve our methods otherwise we wouldn't spend so much time on this board. It's interesting that you decided that your attenuation is the fault of your LME. I suppose you can try another brand or go to DME, but then there are other variables to consider. What if 5 brewers repeated my experiment and it was a conslusion for all that O2 injected wort always finished with the lowest gravity? Would you buy a tank?

 

[Bobby_M]

You're also supposed to get beter results (more o2 absorption) by having the o2 bubbles barely break the surface. By having a lower pressure and smaller bubbles, they stay in contact with the liquid longer allowing more to be absorbed. Also the vigorus bubbling at the surface knocks gas out of solution lowering the total disolved gasses.

I'll buy that. If I determine that O2 injection is indeed better in that it attenuates better than other methods, I will buy a smaller micron airstone. I've been slumming it with the $1 blue stones from Petsmart since I wanted this system to be almost free. It might even be nice to put a 3-way splitter on the end and run 3 airstones, to even further distribute the column of bubbles.

 

[Bobby_M]

If you recall, I posted that at 45 hours after pitching (remember the OG was 1.050):

#1 = 1.018 (64% attenuation)
#2 = 1.019 (62% attenuation)
#3 = 1.016 (68% attenuation)

After 70 hours, the SGs are:

#1 = 1.016 (68% attenuation)
#2 = 1.015 (70% attenuation)
#3 = 1.013 (74% attenuation)

This time I had my wife read the hydro and I didn't tell her what I expected it to be, nor does she care ;-)

These probably fall inline with what everyone expects and that's a good thing. Let's just assume I was able to repeat these results and O2 always proved to attenuate a couple points more than shaking. How many of you folks are running out to get the O2 bottle? Maybe you don't like dry beers, but then I wouldn't suggest Safale-04 for you either.

I would still suggest the O2 or at the very least use a filter with an air pump. They both have the advantage in that they don't expose your wort to potentially infecting air.

 

[david_42]

Excellent. A 6% change in attenuation is quite a bit. Looking at in terms of absolute conversion, O2 was 9% better. Since I already have the air pump & filter, I'll probably stick with them. When the pump dies, I'll consider O2. One stone is probably plenty, given the circulation of the wort during the process.

 

[ColoradoXJ13]

What LHBS do you shop at for your LME? Have you tried DME?

What's Brewin' in Boulder. Yes, I did one with DME and hit the mid-range of the attenuation.

What if 5 brewers repeated my experiment and it was a conslusion for all that O2 injected wort always finished with the lowest gravity? Would you buy a tank?

no, because I really doubt one could taste a difference in .003 SG points, or at least I couldn't

 

[fifelee]

Great experiment Bobby_M. You gave us all more information than we had before. Because of that it was a huge success.

 

[Orfy]

Great result and probably as expected. Are you going to take further readings
I think they may change further over the next 72 hours.

The one thing that I have taken from this personally is that It backs up my feelings that I have no need to aerate/oxygenate further than I do.
I'm all for the KISS approach and will cut out any steps that are not detrimental to my brews. I like my beer to have a malty sweetness and body. I don't want blow offs and am happy to leave it in primary for
5 to 7 days.

These types of experiments are great for dispelling myths.

Thank you for the effort you are putting in.

 

[ayrton]

If you need someone to get rid of the "leftovers" from your experiment, then I'd like to volunteer my services.

 

[mysterio]

Nice experiment Bobby M. The video was hilarious! Any difference in the taste of the finished beers? I suppose you would expect the first one to throw off more fruity esters.

I actually thought the pitching rate was too high to produce such different FGs, but the results speak for themselves.

no, because I really doubt one could taste a difference in .003 SG points, or at least I couldn't

I bet you could, if you tasted them next to each other. I reckon it would be quite noticeable. That's about a 0.4% change in ABV.

 

[Bobby_M]

Since they've only been fermenting about 3.5 days, I'm not quite ready to do taste comparisons. I plan to test the gravity one more time tomorrow just to see if that's where these samples are going to finish. If they all eventually hit the same FG, the conclusion might be that unaerated wort just takes LONGER, but I suspect the variance between the samples will stay fixed.

I did take a pull off the sample on #3 and it was delicious. Funny thing is, it's just a can of Mr Beer LME and some Cascade. Note: since the volume of each is so low, I've been carefully sanitizing my test tube and hydro so that I can return each sample back into the fermenter. I know the science is bad, but I still want to DRINK this batch after all the testing is done.

I wanted to make sure everyone understands that my intent of this experiment was not to taunt or discredit anyone who doesn't care about O2 or wants to keep their brewing as simple as possible. I acknowledge that amazing beers can be made with the most meager equipment.

Ayrton, If they made 2 oz bottles, I'd share a bit with everyone who's responded but they don't so I guess I'm gonna have to muscle the results down on my own. Dang.

 

[Orfy]

Bobby, It's great that you are doing this.

People who done aerate will be biased to no aeration and those with shiny 02 systems will be biased towards using them (usually)

 

[Bobby_M]

no, because I really doubt one could taste a difference in .003 SG points, or at least I couldn't

As was mentioned, it's almost a 10% alcohol content difference. In previous threads, we threw around the concept that O2 saturation simply gets your yeast to attenuate in the range you would expect based on the strain in ideal conditions. I suggested that while you may want a sweeter/maltier beer, you can still do so by either using a lower attenuating yeast like Danstar Windsor or simply add more unfermentables to your brew (pils malts) or powdered Lactose, etc. Sure, we're splitting hairs at this point but the I would rather control the process rather than pitch and see.

In other words, why try controlling dry/sweet by varying yeast health or cell count?

 

[Bobby_M]

Bobby, It's great that you are doing this.

People who done aerate will be biased to no aeration and those with shiny 02 systems will be biased towards using them (usually)

That's just the way isn't it, especially if you've spent money. I'm in a weird spot. My whole O2 setup cost me under $10 (the stone and some tubing) so I'm not vested. I was secretly hoping that #2 kicked a$$ so that I could Ebay the bottle reg to some unsuspecting shmuck who doesn't read HBT.

 

[fifelee]

There is some info on BrewMonkey.com (supposedly from Wyeast Laboratories) that backs up your finding. It says that O2 is better than shaking. It also surprisingly says that aquarium pumps are no better than shaking. That sucks…I was thinking about getting one. But, it seems like they could have tested the aquarium pump for a longer time. Thank again Bobby_M.

 

[Bobby_M]

Let's take a harder look at shaking vs. pumping filtered air.

Shaking: You're basically restricted to getting some of the O2 out of the air that's in the headspace of your fermenter. Of course, of that air volume, only 20% is O2. You can shake for 6 hours straight and the most O2 you'll dissolve is that 20% of the headspace. Of course, you can uncap, purge the air and let new fresh (or is it contaminated) air back in and do it again.

Pumping: At least you you can run it for a really long time without worrying about contamination. I think the issue with the pumping alone is that the bubble rise up out of the wort quickly. I think a combo of pumping and shaking would be better than just pumping because you're forcing the air back into the wort to give it time to absorb o2. In fact, I just started wondering why I hadn't thought to shake my fermenter a bit as I'm pumping O2. After about 20 seconds of O2, I'd assume the headspace is saturated. A quick shake would put that back into suspension at least for a couple minutes.

 

[magno]

This is a link posted by mysterio http://www.maltosefalcons.com/tech/MB_Raines_Guide_to_Yeast_Culturing.php

In the article it lists some of the benefits of O2 vs an air pump vs shaking, as well as different wort compositions and nutrients. The article is mainly about making starters, but some of the concepts hold true for fermentation.

For my last batch, I aerated the starter intermittently with an air pump and filter. Previously I had either shaken it, or used the pump only at the beginning. Aerating intermittently seemed to do something, as I got my first blowoff with this batch.

Good job on the experiment, Bobby_M.

- magno

 

[Bobby_M]

Ok, so it's been six days since I pitched on this experiment.

If you recall, I posted that at 45 hours after pitching (remember the OG was 1.050):

#1 = 1.018 (64% attenuation)
#2 = 1.019 (62% attenuation)
#3 = 1.016 (68% attenuation)

After 70 hours, the SGs were:

#1 = 1.016 (68% attenuation)
#2 = 1.015 (70% attenuation)
#3 = 1.013 (74% attenuation)

After 144 hours or 6 days, the SGs are:

#1 = 1.012 (76% attenuation) 5.1% ABV
#2 = 1.013 (74% attenuation) 4.9% ABV
#3 = 1.011 (78% attenuation) 5.2% ABV

I'm surprised that the shaken sample didn't fall in the center as it has been. In any case, I don't think these results are as impressive as i would have thought but I'm sure it is being affected by the rather high pitch rate. I suspect that if my pitch rate was halved, there would be a more dramatic difference between the three samples. That is, the ultimate attenuation would have been dependent on the yeast's ability to reproduce to adequate cell counts. I think sample 3 would have pulled well above the rest.

Here's an idea. If you like dryer beers, stay away from Safale-04 + O2.

 

[medic_35057]

Room air is 21% O2, Medical O2 is 100%. In your video was the O2 cylinder filled with room air or was it filled with medical O2? What rate did you have your regulator set? You can set those things anywhere from 1 lpm to over 25 lpm. Just curious. I wonder if adjusting the rate of flow out of your O2 cylinder would affect your outcome?

 

[Kaiser]

Room air is 21% O2, Medical O2 is 100%. In your video was the O2 cylinder filled with room air or was it filled with medical O2? What rate did you have your regulator set? You can set those things anywhere from 1 lpm to over 25 lpm. Just curious. I wonder if adjusting the rate of flow out of your O2 cylinder would affect your outcome?

The welding O2 is 100% O2 as far as I know and the regulator he used cannot be set to a particular flow rate like the one on medical O2 equipment.

Kai

 

[Bobby_M]

To clarify, I do have my bottle filled with pure O2. Why would I use compressed air anyway? This is a medical bottle with a precision flow rate regulator. I had it set at 1.5 lpm (at least I think it's rated in liters per minute). Any faster than that, the wort would foam out of the neck of the carboy before the two minutes are up.

I suppose a longer O2 injection cycle would get a little more into saturation, but given the high pitch rates, I don't think it would have increased the attenuation at all.