Deoxygenation Revisited


Deoxygenation is paramount for the low oxygen brewing method, as we have detailed before here on the blog, and don’t worry I’m here to assure you this has not changed.
However as with all things in life sometimes we need to stop, re-calibrate, re-evaluate, and determine if the methods are still valid and optimal. We are now 4 years from most of the data published on the blog (along of course with the paper itself) which is quite some time. This also just happens to coincide with a recent building of the Bio Reactor, to allow for new in-depth and precise data collection. So no time like the present for re-evaluation I would say!





While there are a number of methods for deoxygenation, today we will detail two, the ones we find the easiest and most efficient, Preboil and Yeast Deoxygenation. Time to start the tests (or studies as I like to call them).



Preboil
Pretty self explanatory, the boiling of strike water to eliminate DO.

Study includes: 10 gallons of RO water, 11000 watts in the HLT.
Study started: 14:12
Parameters logged: Temperature, DO
New Variable: NA

Temperature drop at end was the start of chilling the HLT as test was completed

DO raise at end was due to open chilling of the HLT post test

Overlay of All Variables




Summary:
As you can see from the above, as temperature raises, DO has an inverse and falls. When 100c (212f) is reached DO hits terminal (0 ppm). This took roughly 24 minutes in this test. Obviously the 11k watts of power had a great effect on time and efficacy. None the less, this is a very valid method for the dexoygenation of water. *Conversely there has been some recent backlash that boiling water does not remove all DO, this should stop that in its tracks.




Yeast Deoxygenation (Also referred to as YOS for Yeast Oxygen Scavenging). We talked about yeast deoxygenation for removal of oxygen in strike water here. I took the dosage we have recommended for batch size (water needed to be deoxygenated in gallons) x 2 (in grams). So , for example, 10 gallon batch size x 2 = 20 grams of yeast and sugar (any kind of simple sugar). Or to easily refer to as 2g/gal dosing.

Study Includes: 10 gallons of RO water (no minerals), 20 grams of table sugar (sucrose), 20 grams of Red Star Active Dry Yeast, room temperature water.
Study started: 17:40
Parameters Logged: Temperature, DO, PH
New Variable: NA




Overlay of All variables




Summary:
As you can see the oxygen scavenging of yeast is very powerful, fast and efficient. After roughly 20 minutes terminal DO (0 ppm) was reached. Minimal effort for this to work was used. Room temp water, some sugar and yeast, and you can have zero DO water very quickly. If you note these graphs they show ~26 hours of hold time as well, but in reality I let this test run for 96 hours with the same results! Crazy right?!? These results sparked more YOS tests (7 to be exact), since it was so efficient. It should also be noted, pH was effected which could has some effects on mash pH, so keep that in mind.




Yeast Deoxygenation #2
Study Includes: 10 gallons of RO water (no minerals), 1 gram of table sugar (sucrose), 1 gram of Red Star Active Dry Yeast, room temperature water.
Parameters Logged: Temperature, DO, PH
New Variable:.1g/gal dosage rate




Summary:
No graphs for this one, but it was a test to test extremes, from a dosage of 2g/gal to .1g/gal. It did lower DO, however it stopped at 1 ppm. Which considering all things did super well for what it was, ever though it was deemed a failure.



Yeast Deoxygenation #3

Study Includes: 10 gallons of RO water (no minerals), 10 grams of table sugar (sucrose), 10 grams of Red Star Active Dry Yeast, room temperature water.
Parameters Logged: Temperature, DO, PH
New Variable: 1g/gal dosage rate


Summary:
No graphs for this one either, but it was a test to up the dosage of .1g/gal to 1g/gal to.  It did lower to terminal DO (0 ppm), but took nearly an hour. This test seemed to have a correct lower dosage, but time for a temperature variable change



Yeast Deoxygenation #4

Study Includes: 10 gallons of RO water (no minerals), 10 grams of table sugar (sucrose), 10 grams of Red Star Active Dry Yeast
Study started: 22:06
Parameters Logged: Temperature, DO, PH
New Variable: High re-hydration temperature water of 40c (114F)




Overlay of all Variables




Summary: 
As you can see again the oxygen scavenging of yeast is very powerful, fast and efficient. Even with a dosage of 1g/gal after roughly 20 minutes terminal DO (0 ppm) was reached. Make sure you note that this is heated, so a bit more effort (heating of the water) is needed with this dosage. It should also be noted again, pH was effected which could has some effects on mash pH, so keep that in mind.





Yeast Deoxygenation #5

Study Includes: 10 gallons of RO water (no minerals), 10 grams of table sugar (sucrose), 10 grams of Red Star Active Dry Yeast
Parameters Logged: Temperature, DO, PH
New Variable: Normal re-hydration temperature water of 35c (95F) .




Summary:
This lower temperature variable was added to see the efficacy of a slightly lower re-hydration temperature. The conclusion is that the yeast had exactly the same effect. Roughly 20 minutes terminal DO (0 ppm) was reached. 






Final Conclusion

First thing I have to say is that the bio reactor is pretty much the coolest thing ever! I can test all these variables and get tons of great data points, and in this specific case it has allowed us to have some new recommendations on YOS procedures!
At the end of the day you have 2 simple and effective procedures readily available to homebrewers, the preboil and YOS. Either method will do exactly what you need it to do. Strictly speaking from an energy and ease standpoint the default 2g/gal YOS dosing is pretty hard to beat. Dose and wait 30 minutes (to 4 days!) and you are set. If you want to accelerate 2g/gal dosing, heat the kettle a bit.
If you want to cut back on yeast and sugar amount in the water, 1g/gal is a great alternative. You can wait a little longer (>1hr), or slightly heat the kettle to 35-40c (90-115F) and have very fast (<30 minute) results. From my testing of the YOS, I have seen the “murky water” to have zero affect on mash clarity, or have pH move around much. My recommendation would be to dose sulfites when strike temp is reached, give it a minute, maybe a gentle stir and then dough in.
If preboil is more up your alley for a “cleaner” strike water, there are zero issues with that as well, and you can rest assured you will have zero DO water with either.
If you are really astute you will have recognized only 5 out of 7 yeast tests were published, thats because those other two had some really interesting results and we will have to talk about them more another day.
Prost!