Continious Aeration During Primary

[WVBeerBaron]

Just had a though....

I know that aeration (adding lots of oxygen) is key to helping the yeast eat through all of the sugar. I have seen some recommendations that say to aerate often during the beginning of primary fermentation when brewing a big beer/high gravity. I use a sanitized aquarium pump and stone to aerate. If bubbling over was not an issue could I simply leave the pump and stone pumping air during the first 48 hours or so? Or is this overkill? Thanks for any help.

 

[Walker]

you want air in there at the start because yeast use it to replicate. After they have finished replicating, you don't want any more air in there.

48 hours is probably overkill. You'll be pumping in air that is not going to be used by the yeast (they will have finished propagating and will be finally eating sugar, and have no more need for air.)

You can probably do it for the first couple of hours, but I wouldn't do it much more than that.

 

[peoplesbrewingcoop]

you want air in there at the start because yeast use it to replicate. After they have finished replicating, you don't want any more air in there.

48 hours is probably overkill. You'll be pumping in air that is not going to be used by the yeast (they will have finished propagating and will be finally eating sugar, and have no more need for air.)

You can probably do it for the first couple of hours, but I wouldn't do it much more than that.

Not only do the yeast replicate somewhat, the most important part of aerating the beer is to get the yeast to produce products important for next cell growth such as unsaturated fatty acids needed for cell membrane development. When brewing beer, most of the replication of yeast occurs during fermentation. Yeast use the malt sugars in the primary to create energy which they use to reproduce. Their byproduct is ethanol which we love.

If you continuously add oxygen to the primary then you will not get enough fermentation as fermentation will stop in high concentrations of oxygen. Oxygen also stresses out yeast. Oxygen is the most toxic chemicals on our planet. If you have stressed yeast then you get stressed beer.

 

[KingBrianI]

Oxygen is the most toxic chemicals on our planet.

OH ****! We're all gonna die!!! We're all sitting in 21% O2 right now!

 

[Walker]

OH ****! We're all gonna die!!! We're all sitting in 21% O2 right now!

Well, I just let some yeast farts go in my cube. I'm probably sitting in something more like 40% nitrogen, 10% O2, and 50% methane.

 

[Bobby_M]

OH ****! We're all gonna die!!! We're all sitting in 21% O2 right now!

Well, it's a good thing 21% isn't too toxic for us. Go to 100% for too long and see how that does ya.

You could never go over 8ppm on pumped air though so it would be fine to do that for the first 2 days. You'd definitely foam out though.

 

[lamarguy]

Could I simply leave the pump and stone pumping air during the first 48 hours or so? Or is this overkill?

You want aerobic activity early on (first 2 - 4 hours) for sufficient yeast growth and metabolic preparation (e.g., consumption of FAN, minerals, vitamins, etc.). After that, you want to deny the yeast oxygen (i.e., anaerobic activity) to produce ethanol, esters, etc.

If you continuously aerated the wort during fermentation, you would make a very large yeast biomass, not beer. Your goal is to make beer.

 

[peoplesbrewingcoop]

OH ****! We're all gonna die!!! We're all sitting in 21% O2 right now!

It is destroying our own cells as we speak. One of the reason we age. Then the free radicals give us cancer. I wish I could be faculatative anaerobic like yeast. :cross:

 

[shanecb]

I have to ask... why is it commonly recommended to aerate a mead daily before the 1/3 sugar break but not beer? I've always aerated my meads until then with success. I've never done it for beer because people don't seem to, but why is mead different in that regard?

 

[WVBeerBaron]

i'd say because typical OG for mead is over 1.100, while most beer doesn't go so high. With so much extra sugar to eat through the yeast can use all the extra help they can get.