The definitive aeration/oxygenation experiment

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ColoradoXJ13 said:
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.


ColoradoXJ13 said:
...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).


ColoradoXJ13 said:
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?
 
D*Bo said:
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.
 
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.
 
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.
 
RichBrewer said:
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.


Bobby_M said:
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 :drunk:
 
Great experiment Bobby_M. You gave us all more information than we had before. Because of that it was a huge success.
 
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.:mug:
 
If you need someone to get rid of the "leftovers" from your experiment, then I'd like to volunteer my services. :D
 
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.
 
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.
 
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)
 
ColoradoXJ13 said:
no, because I really doubt one could taste a difference in .003 SG points, or at least I couldn't :drunk:

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?
 
orfy said:
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.
 
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.
 
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.
 
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
 
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

attenuation.jpg



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.
 
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.:D I wonder if adjusting the rate of flow out of your O2 cylinder would affect your outcome?
 
medic_35057 said:
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.:D 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
 
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.
 
I'm jumping in on this thread late, and I'm rookie compared to most in this forum; but I wanted to throw in my $.02. Coming from a biology/natural resources background, this caught my attention and the geek lobe of my brain went into temporary overdrive.

Although this is not what the scientific community would consider "good science", I think it speaks enough to be continued.

I raise fish. Fish need oxygen to live/eat/reproduce. So does yeast. I spend a lot of my time in the summer making sure my fish have enough 02 dissolved into the water (Dissolved Oxygen, or DO), almost always measured in Parts Per Million, or ppm (same as mg/L).
So, couldn't we just brew up some wort, pitch, aerate with the different methods, then measure the DO for each method?
Does anyone know of a specific DO level that is best for the yeast, or is it simply more=better? I would assume that just like all other types of organisms (fish, crustaceans, insects), certain species, or strains of species, in the case of our yeasts, would outperform other strains at lower DO levels. If we knew the answer to that, people could choose yeast varieties based on whether they choose to aerate or not, and still achieve best possible results.

I'm thinking that the next time I brew, I'll drop my DO meter into some wort, to see if it will even measure the DO in a solution such as beer wort. I can't see why it wouldn't. Then I could possibly move on to finding out which DO level would work best.

I also would imagine that the yeast companies have already done some work like this, and the results were either irrelevant and not worth publishing to the public OR MAYBE so important that technically advanced breweries pay top dollar for the information. ????? Hmmm.

Way to get our attention BobbyM!! I think your experiment could lead to more experiments and hopefully a better understanding of what the hell is really going on inside that carboy! :mug:
 
Hey Brehm21, if you have the equipment to measure dissolved oxygen, then you could do your own test to help out on this question. A fundamental question (precursor to asking what effect different oxygenation methods have on fermentation) would be 'How do different oxygenation methods perform at increasing the dissolved oxygen content in wort?'

You could replicate Bobby_M's basic design by making three identical batches of wort, measuring the DO in each (to ensure consistency), and then using shaking to aerate one, then direct oxygenation with an aeration stone for the third. Let sit for a half hour, then measure the DO content in each.

Of course, you could also replicate the rest of Bob's experiment by taking gravity readings, pitching yeast, and tracking fermentation. That would be interesting, too. Perhaps you could even pitch a smaller amount of yeast as per Bob's suggestion.
 
brehm21 said:
I raise fish. Fish need oxygen to live/eat/reproduce. So does yeast. .....

Way to get our attention BobbyM!! I think your experiment could lead to more experiments and hopefully a better understanding of what the hell is really going on inside that carboy! :mug:

Thanks. Everything I've read says that they need O2 to reproduce, but they only begin to eat/convert sugars in an anaerobic environment. That would suggest that if you already have enough yeast cells to get through all the fermentables (who knows exactly how much that is), you really don't need O2. That's why I was suggesting that this experiment would have been better if I underpitched.

I tend to think that the simple answer, if you don't want to go buying an O2 system, is to simply pitch more yeast. This is basically what you're doing when you make a starter.

Testing DO is a reasonable idea but I wonder if it will be accurate in a higher gravity liquid. Maybe it's calibrated for fresh/sea water? Well, at least you'd have reasonable relative figures. Maybe just boil a bunch of water for an hour to deplete the O2, then try the different methods to aerate and then retest DO.

I was unable to test this intermediate data. I was testing the end fermentation results of different aeration methods but I don't know how much O2 saturation I actually acheived. You could break this down to a few other experiments to be more conclusive.

1a: Which methods produce the highest O2 saturation. 1b: If equal, which ones are faster.

2a. Under low pitch rates, which DO levels produce the shortest lag time? 2b: which DO levels produce the best attenuation.

3. Repeat 2a and 2b with high pitch rates.

I'd volunteer to run the test again if someone wants to loan me a refractometer (to take more frequent gravity readings without pulling huge samples) and a DO meter.
 
I'll have to get my DO meter out and read up on testing liquids other than water. I know it will read DO in some really nasty water, but the sugars could possibly play havoc with the sensor.
I'll check it out. Unfortunately, I won't brew until next week at the earliest.
 
medic_35057 said:
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.:D I wonder if adjusting the rate of flow out of your O2 cylinder would affect your outcome?

Kai said:
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.


Oddly enuff I found out at my last Mortality and Morbidity confrence that industrial O2 is actually cleaner and more "pure" then medical O2. I guess the reasons behind it are your body can handle some contamination (it's built for it) but in industrial purposes the tolerances are stricter becuase the materials it's used for cant compensate.

I dont know how true the info presented to me was but i found it interesting.
 
Holy Molly.. WOW.

My brain hurts now.... The inner geek is flush with envy.

I had a question and WOW what an answer... Got to love the Search and the people on this forum!
 
I know this was done back on 07, but I just found it and I wanted to say thanks for your time and effort to apply science to such a controversial issue. Great read and much appreciated!
 
3. Are there any aspects of my methods that may tarnish the results that I just haven't thought of? The only one I've recognized is that a 45 minute boil may not have fully depleted the disolved oxygen. I should have boiled the water for 30 minutes prior to adding anything.

You mentioned this early on but I don't think anybody responded. I want to put your concerns at ease in regards to not fully depleting the oxygen in the wort.

I am an engineer at a power plant. We boil water to make steam and send that through a turbine. In that process, it is very important to remove oxygen from the water prior to putting it into the boiler to prevent corrosion in the boiler tubes. To remove the oxygen, we use a contraption called a deaerator. Basically, this uses steam to heat the water up to right before the boiling point. This process actually brings the oxygen level under 1 part per billion (essentially no oxygen left in the water). So, your wort was most likely devoid of oxygen as soon as (or before) it started boiling.
 
My major criticism is using gloves instead of condoms. I think seeing which condom got erect first would have truly been the definitive proof of fermentation that is needed. That being said, great experiment!
 
I just caught onto this thread. I tried reading through it and as best I can tell everything is based off the idea that the value of O2 is in a fast fermentation and high attenuation. Below is an excerpt from some of my research that I am too lazy to retype so its directly quoted,

"Oxygen is critical for yeast health. The aerobic respiration yields far more energy than anaerobic fermentation, which is exactly what yeast need as they multiply. As well, oxygen is used during the lag phase to desaturate fatty acids which is critical to maintain cell membrane fluidity as the yeast multiply. This fluidity is critical since if the membrane is too rigid it can not as readily reabsorb diacetyl."

So, what you do at the onset of fermentation pays dividends at the end of the process with healthier yeast. If you re-pitch yeast it is that much more of a benefit.
 
This was a great thread. Thanks to Bobby M and the others for their input, even though it was 3 years ago.

Wonderbread23: I'd get nervous about the part where he puts holes in the gloves, (think about holes in condoms)
Good info.
 
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