Maybe there is a chemistry graduate student that could take on experiments that measure O2 adsorption of wort/beer over time in a brewing environment. It does seem that everyone is in more or less agreement that the CO2 blanket concept is a misnomer and at worse, a misunderstanding of gas and laws of physics. It is a very interesting discussion however.
I have a few practical application or technique questions then, since this seems counter to many homebrewer's observations:
1. Yeast take up O2 (dissolved in the wort, not from the air) at least in the lag phase and past primary fermentation this is often believed to help prevent oxidation (I wish I could remember where I heard or read this). This appears to be untrue - as I have heard many BJCP judges state the same as Yooper. Bottle conditioned beer then should not be oxidized, unless oxidation occurred before or during bottling, correct? It seems that some people (award winning brewers) have a handle on this - and the general wisdom is the CO2 blanket idea. Everyone I have talked to supports the idea of a blast of CO2 protects the surface of beer when handling/transferring.
2. This may mean that "purging" techniques may only be effective if done specifically to introduce a high pressure differential at the bottom of a vessel (assuming the opening or valve is at atmospheric pressure) - expanding CO2 mechanically "pushing" out much of the ambient gasses like a rocket - for example - purging an empty corny using the liquid side and dip tube to put 3-5 lbs of pressure into the bottom accelerating the gas out through an open top or the pressure release valve. I am guessing this is slightly less effective than pushing a corny full of water or sanitizer out with CO2? or not? Same process for counter pressure bottle fillers that allow a burst of CO2 to purge the bottle before filling.
3. When using a secondary (very rare for me), it seems common sense to eliminate the beer surface area contact with air filling to the neck of the carboy, but not always practical. I have tried both the CO2 purge and the technique of adding a minimum sugar addition to allow new fermentation to create CO2 - and hoping that bubbling activity would provide a barrier between the beer and air. Or does the immediate application of an airlock trap the "air" causing it to mix homogeneously into the producing CO2 until the pressure begins to expel gas through the airlock?
Yes, occasionally I get oxidized beer. Sucks. Happens less and less the better care I take in handling.
I just read back through this and not sure I made a whole lot of sense. Perhaps I answered my own questions by assuming that we need to treat beer delicately through any transfer or exposure to air (or better in a sealed environment under pressure), and that most serious oxidation occurs when wort/beer is splashed or agitated (oxygenation by mechanical means), and natural aging oxidation occurs as O2 transfers through plastic, wood and or metal by passive means. It seems both can be addressed by proper processes and proper handling and storage, minimized but never completely avoided.
I have a few practical application or technique questions then, since this seems counter to many homebrewer's observations:
1. Yeast take up O2 (dissolved in the wort, not from the air) at least in the lag phase and past primary fermentation this is often believed to help prevent oxidation (I wish I could remember where I heard or read this). This appears to be untrue - as I have heard many BJCP judges state the same as Yooper. Bottle conditioned beer then should not be oxidized, unless oxidation occurred before or during bottling, correct? It seems that some people (award winning brewers) have a handle on this - and the general wisdom is the CO2 blanket idea. Everyone I have talked to supports the idea of a blast of CO2 protects the surface of beer when handling/transferring.
2. This may mean that "purging" techniques may only be effective if done specifically to introduce a high pressure differential at the bottom of a vessel (assuming the opening or valve is at atmospheric pressure) - expanding CO2 mechanically "pushing" out much of the ambient gasses like a rocket - for example - purging an empty corny using the liquid side and dip tube to put 3-5 lbs of pressure into the bottom accelerating the gas out through an open top or the pressure release valve. I am guessing this is slightly less effective than pushing a corny full of water or sanitizer out with CO2? or not? Same process for counter pressure bottle fillers that allow a burst of CO2 to purge the bottle before filling.
3. When using a secondary (very rare for me), it seems common sense to eliminate the beer surface area contact with air filling to the neck of the carboy, but not always practical. I have tried both the CO2 purge and the technique of adding a minimum sugar addition to allow new fermentation to create CO2 - and hoping that bubbling activity would provide a barrier between the beer and air. Or does the immediate application of an airlock trap the "air" causing it to mix homogeneously into the producing CO2 until the pressure begins to expel gas through the airlock?
Yes, occasionally I get oxidized beer. Sucks. Happens less and less the better care I take in handling.
I just read back through this and not sure I made a whole lot of sense. Perhaps I answered my own questions by assuming that we need to treat beer delicately through any transfer or exposure to air (or better in a sealed environment under pressure), and that most serious oxidation occurs when wort/beer is splashed or agitated (oxygenation by mechanical means), and natural aging oxidation occurs as O2 transfers through plastic, wood and or metal by passive means. It seems both can be addressed by proper processes and proper handling and storage, minimized but never completely avoided.
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