| Author |
Message |
    
Joseph Listan
Intermediate Member
Username: Poonstab
Post Number: 435
Registered: 03-2003
| | Posted on Monday, January 17, 2005 - 06:27 pm: | 
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How do you get HSA when hot liquids resist O2 take-up? I've never figured that out.
Cold Side Aeration I can believe, but HSA?
Especially HSA before the boil. Wouldn't the boil drive off almost all of the previously HSA'ed O2 (from the mash, for instance)? Is there something special about the heat that makes the O2 non-evaporable from then on? My knowledge of chemistry is limited, so please help me understand. |
Brandon Dachel
Senior Member
Username: Brandon
Post Number: 1385
Registered: 03-2002
| | Posted on Monday, January 17, 2005 - 06:34 pm: |
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HSA is not the physical dissolving of oxygen (air) in a hot liquid, but rather a chemical process.
I find the arguement moot anyways as none of my beer lasts long enough to get stale anyways. |
q-ceps
Junior Member
Username: Qceps
Post Number: 52
Registered: 11-2004
| | Posted on Monday, January 17, 2005 - 06:42 pm: |
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I think this is the difference between dissolving O2 and bonding it chemically to other compounds (oxidation). At low temeratures, O2 will just dissolve into wort and linger slowly oxidizing whatever has affinity toward it. At higher temperatures, the solubility of oxygen is lower, but the tendency of wort constituents to oxidize would be much higher. I would think some of these oxidation reactions are reversible (and the boil can shift the equilibrium back, thus reversing some damage), but in all likelihood most are not. Yeast can use disslved oxygen readily. It can not directly reduce all oxidized compounds in wort, which is why HSA survives fermentation. |
q-ceps
Junior Member
Username: Qceps
Post Number: 53
Registered: 11-2004
| | Posted on Monday, January 17, 2005 - 06:44 pm: |
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As a point of interest, I once heard of an idea to add peroxide to wort instead of aeration. Never heard if anyone tried it and how it would have turned out, but my feeling is what a complete disaster that would be. |
Bill Pierce
Moderator
Username: Billpierce
Post Number: 1865
Registered: 01-2002
| | Posted on Monday, January 17, 2005 - 06:59 pm: |
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As I understand it, it's a combination of what Brandon and q-ceps suggest. At high temperatures the oxygen (even in the tiny amounts that are soluble) is active and bonds with compounds in the mash and wort to produce other compounds that act as precursors and catalysts for oxidation that occurs later as the beer ages. Of course the real question is the effect this has on flavor, that is, whether HSA actually can be detected in the beer. On that there is no consensus whatsoever. My own conclusion is that the effects are small indeed. |
Denny Conn
Senior Member
Username: Denny
Post Number: 4086
Registered: 01-2001
| | Posted on Monday, January 17, 2005 - 07:00 pm: |
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I can assure you it's real. I've tasted a friend's badly oxidized beer when he had air bubbles in the tubing from his cooler runoff. The first 2-3 months the beer was great, but then almost overnight it developed the classic "wet cardboard" taste.
LIfe begins at 60...1.060, that is.
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Bill Pierce
Moderator
Username: Billpierce
Post Number: 1866
Registered: 01-2002
| | Posted on Monday, January 17, 2005 - 07:02 pm: |
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Q-ceps, peroxide is a strong oxidizer and toxic to yeast. Obviously that's why it is commonly used as a disinfectant. |
Joseph Listan
Intermediate Member
Username: Poonstab
Post Number: 437
Registered: 03-2003
| | Posted on Monday, January 17, 2005 - 09:26 pm: |
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Dissolving vs. chemical reaction. That 'splains it. And I would think theat the heat would be a catalyst in the latter process, so the H'er the S is, the worse the A gets.
I never aerate on the hot side anyway, "just to be sure", but I wanted to know the difference, and this is what I suspected. |
Brews and Views Archive 2005 
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