Exposure to O2.

[Goose5]

I've read about many going through great lengths to put oxygen into the post boil wort. Air stones, oxygen tanks, aquarium pumps ect. I think I read it only puts about 8 to 10 ppm back in? If it this hard to put it back in how can a nice gentile post fermentation transfer exposed to the atmosphere be that bad of a practice?

 

[RPh_Guy]

I bottle, so some oxygen when packaging is practically unavoidable.

Pre-fermentation oxygen is consumed by the yeast.
Post-fermentation oxygen is NOT consumed by the yeast and will oxidize the beer over time.

 

[MGamber]

I think it depends on the style. A west coast IPA or a heavy stout can probably tolerate a small amount of oxygen because the bitterness or malts are so strong you won't notice a little oxidation. A lighter pale ale, lager or NEIPA will suffer with even a small amount of air because, in the first two there's little to cover the off taste and, in the latter, the hops oxidize as well and they turn all kinds of ugly colors and taste stale.

And yes, as mentioned, yeast use the oxygen during fermentation. After fermentation there's nothing in there to remove the oxygen and it's free to do bad things to your beer. That said, beer doesn't oxidize immediately so if you and your friends tear through it pretty quickly (as we do here), chances are it'll be gone before it has a chance to go really bad. If you have a 5 gallon keg and it takes a month or two kick it, you might start noticing the effects after a couple of weeks, if not sooner.

 

[GPP33]

I think the question is “if I try to put O2 in and can only reach 8-10 ppm how much could possibly get in during a transfer”. The answer is: in some cases enough to ruin a beer, in a few enough to make it better and in most enough to make it not quite what it could have been.

 

[AZCoolerBrewer]

Like Rph I bottle. It’s my opinion that in doing so the yeast take care of most of the introduced oxygen while ramping up to eat the priming sugar. I have had instances where the last bottle fill draws in air bubbling and introducing tons of O2 into that one bottle. I don’t believe that the priming action is enough to scrub that much O2. If I ever get around to kegging, I plan to prime my kegs with sugar in hopes of taking this perceived advantage in bottling to my kegs.

 

[Goose5]

This is interesting. AZ in a five gallon keg how much sugar would you use?

 

[Iseneye]

Post boil oxygenation is for the yeast. Post fermentation oxygenation causes staling and oxidation. They are two different functions.

You would be surprised how small an amount of oxygen stales beer post fermentation.

 

[Goose5]

I don't know if I'd be surprised. Tell me how small?

 

[AZCoolerBrewer]

This is interesting. AZ in a five gallon keg how much sugar would you use?

Papazian says 3/4 cup, but I’ve not done it before, so I can’t say from experience.

 

[doug293cz]

I don't know if I'd be surprised. Tell me how small?

0.15 ppm (150 ppb) is enough to degrade hop forward beers.

Brew on

 

[Vale71]

I've read about many going through great lengths to put oxygen into the post boil wort. Air stones, oxygen tanks, aquarium pumps ect. I think I read it only puts about 8 to 10 ppm back in? If it this hard to put it back in how can a nice gentile post fermentation transfer exposed to the atmosphere be that bad of a practice?

That's because the composition of wort and beer differ greatly from each other. If this weren't the case we would just drink cold wort and not bother with the whole fermentation business.
Lots of constituent compounds of beer do not take oxidation well and even at very low oxygen levels will create staling compounds which, in turn, have very low perception thresholds.

 

[myndflyte]

Here is a great write-up on the role of oxygen and yeast: https://www.morebeer.com/articles/oxygen_in_fermentation

 

[mongoose33]

I've read about many going through great lengths to put oxygen into the post boil wort. Air stones, oxygen tanks, aquarium pumps ect. I think I read it only puts about 8 to 10 ppm back in? If it this hard to put it back in how can a nice gentile post fermentation transfer exposed to the atmosphere be that bad of a practice?

Air will get you about 8 ppm; oxygen from a tank can get you higher, much higher if you wish.

Yeast consume the oxygen that's introduced to the wort post-boil, resulting in (if the system is closed) an oxygen-free beer when fermentation is complete.

Oxygen after that point will oxidize the beer. That is not a good thing. It'll diminish hop flavors, potentially create a "cardboard" taste, and reduce shelf life.

And while it's a little bit of an effort to get enough oxygen into the post-boil wort to support the yeast, it takes relatively little post-fermentation to screw up the beer.

 

[Silver_Is_Money]

Oxygen is required by liquid yeast, but Lallemand and Fermentis are on board as stating that it is completely unnecessary with dry yeast (unless it is being saved for re-use post initial fermentation). I'm not sure what Mangrove Jack's says about this.

I recently took Lallemand and Fermentis up on this, and yielded ~6 gallons (64 x 12 oz. bottles) of Oatmeal/Milk Stout for which I did zero aeration, and into which I pitched 1 pack each of rehydrated Windsor and S-04. Fermentation was held to 63 degrees +/- 1 degree, and by roughly 3 to perhaps 3.5 days fermentation was complete, with an apparent attenuation of 73.4%. The beer tasted as good at bottling as any I had previously made when applying aggressive aeration. I perceived no defects due to skipping aeration.

 

[tll77]

This is interesting. AZ in a five gallon keg how much sugar would you use?

I've gotten good results with 70-90 grams. If you have a spunding valve, you can't really mess it up with too much sugar. Just set the spunding valve to desired carb level. If you don't use enough sugar you can increase carb level with force carb.
You will have to seal the keg with pressure first.