Oxygenation vs. aeration

[bpac]

I'm totally confused.

When is adding oxygen good (aeration) and when is it bad (oxygenation)?

I was under the impression that as long as your brew isn't hot, everything should be fine.

I guess I'm just asking, what is the definition of each? I had a potentially stuck fermentation on an Oatmeal Stout (stuck at 1.030 for 4 days straight, 68 degree fermentation, wyeast 1098, no starter) and I racked it to secondary hoping to rouse the yeast to get some more action of out them. I was very rough and splashy on purpose, hoping to give them some O2 to munch on, and now I'm wondering if that was a good move.

I'm sure everything will be fine, and I will RDWHAHB, I just want to learn. Thanks!

 

[BigB]

Aeration is the process of getting dissolved oxygen into a wort prior to fermentation... this helps the yeast get going and reproduce. Oxidation can occur from getting air into the wort at an unwanted time, like post fermentation.. it spoils the beer... for more indepth: http://***********/stories/article/indices/7-aeration/1671-winning-the-air-wars

 

[dcp27]

the only point adding oxygen is good is chilled pre-fermentation (cuz boiling removed it all) as it is necessary for yeast reproduction. after fermentation has begun, oxygen can only spoil your brew, which is one reason many recommend not using a secondary

 

[as1084]

Adding oxygen is only good right before pitching your yeast. Yeast need plenty of oxygen to reproduce and consume the sugars as fast as possible. After fermentation, oxygen is bad. It can spoil and change the taste of your brew, and not in a good way.

 

[pikledbill]

aeration/oxygenation is getting oxygen into wort - as per as1084 and BigB reply, it is good early in the pitching process.

Oxidation is a different critter, it has to do with a chemical reaction that is generally bad for your beer...Oxygen free radicals attacking stuff in your beer is bad. It is worse at higher temperatures...as per BigB reply.

Note that aeration and oygenation are generally used in an interchangeable manner by brewers...Oxidation is something completely different.

Cheers,
PikledBill

 

[Justibone]

If you oxidized your beer, it won't be good for as long. Don't age it, drink it as soon as you like it.

 

[Revvy]

From "Beer Brewing and Dissolved Oxygen" http://www.eutechinst.com/tips/do/09_DO_beer_brewing.pdf

Oxygenation: When and How Much?
Before it all begins: Pre-fermentation
Oxygen is introduced to the wort after boiling, and prior to the addition of yeast. ... the oxygenation process should take place before, not after fermentation has commenced. As fermentation progresses towards completion, oxygen uptake is reduced, and any additional oxygen injected into the wort will not be used off. Instead, it remains to react with other compounds in the beer, creating staleness and undesirable tastes.

...Oxygen control after the beer is brewed
At the end of fermentation, the beer is completely free of oxygen. At this point, the beer is highly susceptible to oxidation, which has the following effects on the end-product:
- Undesirable taste
- Cloudy/ hazy beer
- Increased beer astringency
- Darkened beer colour
There are several ways to prevent oxidation of the beer after fermentation, one of which is to blanket tanks with inert gases. Use only de-aerated water for dilutions, as well as to run through beer transfers, and keep the finished product in cool storage during the supply chain.

From BYO magazine. http://***********/stories/techniques/article/indices/7-aeration/1949-aerating-wort-techniques

Oxygen in beer is undesirable except at one point (and only one point) in the brewing process. That lone point is when the post-boil wort has been chilled down to fermentation temperature, but before the yeast has been pitched into it.

 

[bpac]

crap.

oh well, sounds like i'll just need to drink it quick. shouldn't be a problem.

 

[Geofferson]

Why do you introduce the oxygen right before pitching the yeast as opposed to immediately after pitching the yeast? Does it really matter at all? And would it make a different if you were pitching dry yeast? Or a starter?

 

[dcp27]

Why do you introduce the oxygen right before pitching the yeast as opposed to immediately after pitching the yeast? Does it really matter at all? And would it make a different if you were pitching dry yeast? Or a starter?

no difference x2

 

[flabyboy]

I would think it would fairly difficult to damage your beer with oxygen during active fermentation. Its when fermentation is complete and you transfer it into a secondary vessel that you run the biggest risk. I know with wine we transfer from the primary to the secondary vessel before fermentation is complete. That way your 5.5 gallons of wine has a nice blanket of CO2 sitting on top of it in your 6 gallon carboy.

One question I have for the brewmasters on here. When you rack to secondary and it doesn't come all the way to the top of your 5 gallon carboy, do you top it off with a little clean water to eliminate the airpocket on the top?

 

[pikledbill]

I would think it would fairly difficult to damage your beer with oxygen during active fermentation. Its when fermentation is complete and you transfer it into a secondary vessel that you run the biggest risk. I know with wine we transfer from the primary to the secondary vessel before fermentation is complete. That way your 5.5 gallons of wine has a nice blanket of CO2 sitting on top of it in your 6 gallon carboy.

One question I have for the brewmasters on here. When you rack to secondary and it doesn't come all the way to the top of your 5 gallon carboy, do you top it off with a little clean water to eliminate the airpocket on the top?

Although not a brewmaster, I will answer: no, don't top it off

Cheers,
PikledBill

 

[Justibone]

Topping with water is not soooo good. It thins it out.

Topping with beer, or something related to beer (like Coors Light ), can be acceptable.

 

[Revvy]

In wine making evidently some folks top it off with sanitized glass marbles. This displaces the wine and fills the headspace.