Do you have a lot of iron in you wort? If not how is it the same?
Yes, to get to the reductones in the beer, but it does readily. Oxygen moves into the beer along a gradient of chemical potential i.e. if you put beer which has been protected from O2 i.e. beer in the reduced state under gas which contains O2 the O2 will move into the water as long as that gradient exists. Reduced beer contains reductones. These will absorb that O2, becoming oxidized in the process and removing it from the solution so that the gradient is maintained and O2 continues to flow in until no O2 remains in the headspace and the gradient evanesces. This is why Henry coefficient has nothing to do with it. The Henry coefficient tells us how many mg/L DO are required to equalize the chemical potential of dissolved oxygen in water in equilibrium with the gas over it. Here saturation is never approached as the partial pressure of O2 in the beer is effectively 0 as the O2 is taken out of solution by the reductones....does O2 have to dissolve to cause damage?
Can't it oxidize the surface layer of the beer without dissolving into solution? That's how oxidization occurs on solids like metals, right?
More or less. A good brewer will do everything he can to keep his wort/beer in the reduced state which means avoiding even brief exposure to oxygen on the hot side where damage can be quick and ensuring that the beer, once past the oxygenation which follows pitching (exception for ales that are 'dropped'), is protected from oxygen especially after the yeast are removed i.e. in the package.Dolomieu said:Is O2 the only oxidizer you are concerned with? If so why?
This is all great theory. Lots of things could happen but in practice your posts read as verbal masturbation.
If you want a demo on how gasses mix/settle, get some dry ice and toss it in a bucket. If you think there is any O2 left try breathing with your head in there. (Please don't)
This is the Brew Science page where we have
"In depth technical threads related to the biology and chemistry of home brewing"
If you want a demo on how gasses mix/settle, get some dry ice and toss it in a bucket. If you think there is any O2 left try breathing with your head in there. (Please don't)
Classic mountain made of a mole hill
I don't think that analogy is sound. Dry ice fog is not only CO2, but also water, which is extremely heavy. The fog is also very cold. These characteristics make that more of an apples to oranges analogy in this discussion.
I will ask that personal attacks and comments not be in any of the posts. Thanks!
I understand that and have been following you. Now make that 20% Air (which only 20% of that is O2) 80% CO2. This is where I believe the meat is. Talking as if there is 20% pure O2 in the keg is misleading.
...........{snip}.......If you purge with CO2 3 times to get air down to 1/27 of a kegfull (that's 700 mL of air with 140 mL of O2 in it) and then fill with beer until it comes out the gas line and PRV you will have pushed out all the air and while you have exposed the beer to that 140 mL of oxygen during the filling process that is 27 times better than the exposure it would have had if you filled the keg w/o having purged first.
And for me, that's been good enough for all of my kegs.
I purge, keg, purge, and set it in the kegerator. Normally, the beer is gone in a couple of weeks, but not ever more than a month. Since oxidation flavors worsen with time, this really hasn't been an issue with me at all.
Of course, I drink my beer pretty quickly. If I'm not drinking it quickly, then I will bottle (via my beergun) it but that's only happened a couple of times in the last few years.
I don't think that analogy is sound. Dry ice fog is not only CO2, but also water, which is extremely heavy. The fog is also very cold. These characteristics make that more of an apples to oranges analogy in this discussion.
Oh, and English real ale needs a small amount of oxidation to get the best flavor from the it. Controlled amounts of oxidation can be a good thing as long as all the oxygen present is then bound up, and the beer doesn't oxidize further.
Slight oxidation flavors can be very pleasant- a "sherry" or sweet-ish "brandy" flavor is most common and very nice in barleywines and in some other dark beers.
The key to a great cask isn't the "bound up" oxygen, but instead that the cask is emptied before the beer deteriorates to an objectionable flavor.
You can taste it- the first pint is much different than the last pint as the beer oxidizes.
Slight oxidation flavors can be very pleasant- a "sherry" or sweet-ish "brandy" flavor is most common and very nice in barleywines and in some other dark beers. They aren't great in pale ales, though, and of course they worsen with time. A slight flavor of oxidation today could be cardboard flavor in 2 months.
This is an interesting concept to me. I have always thought of oxidation as 100% bad. So do you think preventing a barleywine from getting any oxidation might effect the flavor profile negatively? Traditionally brewers did not know the science behind brewing as much as we do today and the styles we know and love today reflect their processes. So might we, by protecting certain styles too much, deviate from the spirit of the style?
I wonder how permeable our rubber bungs and better bottles are? Gases can and will transfer through solids. Here is an excerpt taken from:
Ask and yee shall receive http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf the better bottle guys did a pretty serious look at closures for carboys.
Enter your email address to join: