CO2 Purity and Why It's So Important

Brewing Processes
21

It’s an interesting but moot point, as all grades of CO2 99.5% or purer list O2 impurity in ppm.

22

I’d be interested to hear about that.

23

Cool, thanks for the detailed response!

So at least on the cold side, it seems like homebrewers have (more or less) two options to minimize cold side aeration effectively:

  1. Complete keg purging+careful closed transfer+spunding+food-grade CO2+cold storage – slow, but the Cadillac option in terms of minimizing oxygen content at start

  2. Complete keg purging+careful closed transfer+food-grade CO2+cold storage – faster, some potential for near-term oxidation, but likely minimal if you follow this protocol precisely with high-quality CO2 and careful keg purging.

And adequate purging and good quality CO2 really are the key steps.

24

Yup. Spunding eliminates the real damaging amounts of oxygen by eliminating the need to force carbonate. Serving using bottle gas is a required evil for anyone.

The reason we found this topic in particular so important is that it affects all of us.

25

It’s great to have a DO meter so that you can test the purity of your Co2. Unfortunately a decent one costs about $8K… I would gladly test anyone’s Co2 for them for a small fee.

26

Orbisphere?

27

While it is no doubt good to be AWARE of this issue, as I see it, there’s simply nothing I can do about it; I have to take my CO2 as I find it.

Am I a total outlier here in thinking that this is a bit of a non issue because, as a homebrewer, I have the luxury of drinking my beer quite fresh (kegs are nearly always gone in 2 weeks), so I can relax about what is primarily a shelf life concern (as long as I’m not doing full on LO?)

28

I find it interesting, in that it’s brewing related so therefore interesting by default. I have no doubt that it’s a major issue for someone. For me it’s trivial and unfixable, so in effect I would almost be better off not even knowing about it. Interesting, but…

29

It’s not a matter of IF you can do something about, Spunding solves the force carbonation issue, but rather a matter of if you WANT to. That’s a choice you would have to make.

30

But what about serving?

31

I don’t think you are an outlier here–my sense based on my interpretation of these same results and the above conversation is that for brewers who handle their stuff with at least moderate care, and consume quickly, there isn’t any major reason to worry. I might change my mind on that point with some rigorous tasting data (which unfortunately don’t exist yet, as near as I can tell), but at least for now the issue is lower down the priority list for me.

(again, I’m not saying that it shouldn’t be of concern, just that it would be really nice to see quantitative evidence for a perceptible impact for a typical beer drinker at the homebrew scale under homebrew consumption conditions).

32

Well, like I said a few posts back, serving is a necessary evil, but it accounts for a much smaller percentage of the total O2 introduced in ppb. You be way under the 150 ppb mark if you spunded and only used bottle gas to serve.

33

Rigorous tasting data, not rigorous testing data:  One letter makes a big difference in what I would find significant!

34

Here is a write up on cold side oxidation taste tests. Not spunding versus force carb but I still find it related enough to post here.

35

If there is anything I have taken away from homebrewers in general when presented with any type of scientific evidence  they scream for blind tasting to prove anything/everything. Even when presented with said things, if it goes against their bias, they discount it.

The moral of the story is accept there is an issue or don’t, try new methods or don’t. But the science is the science and that doesn’t change regardless of bias, stubbornness, comprehension, etc. It is what it is.

36

I love how everyone seems to be mystified about how NEIPA oxidizes faster than all other beer. It’s really no secret but it is a more advanced topic for homebrewers. The short  answer is this:

Oats are very high in fats and lipids and manganese (fenton reactions)
Hops are very high in polyphenols and mangenese
Homebrewers (in general) don’t purge properly
Homebrewers (in general) force carbonate

Homebrewers in general are very sloppy when it comes to trub in the fermenter. Yes yeast like some trub and some trace metals for reproduction, but we are talking like 1/100th of what ends up in fermenters.

So you have a lot more then normal fats and lipids, and a metric ton of manganese from the malts and the hops. It gets the slightest trace of o2 and you have an atom bomb of reactions happening. If you are rigorous with trub separation, and transfer to a purged keg and spund you negate nearly all of the reactions. Doing so results in a NEIPA that is brewery fresh for 6+ months.

37

And on the other hand here’s another one (referenced in that one but I think more on topic here):

EDIT  sorry this link doesn’t seem to work. Its reference in the NEIPA article.  Check it out. The link there works!

38

The problem with this, and basically all homebrew experiments, is that all the beer is oxidized before they even start. But I am not going down that rabbit hole here, not worth it.

39

So good practices upstream, like careful mashing to avoid lipid extraction and rigorous trub removal, combined with more moderate hop rates and good purging, may be mitigating to some degree the hazards of bottle CO2  in the Pilsner type beers that I brew.  Seems to be working, but of course no triangle tests, just experience guiding my methods.

40

We have a Beverly.