Free oxygen may be boiled out, but oxidation is a chemical change. You cannot 'boil out' oxidation.
HSA may not matter much to homebrewers, but there is a lot of evidence that HSA alone causes paper notes (trans-2-nonenal) in beer.
Hot side aeration while sparging
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Free oxygen may be boiled out, but oxidation is a chemical change. You cannot 'boil out' oxidation.
HSA may not matter much to homebrewers, but there is a lot of evidence that HSA alone causes paper notes (trans-2-nonenal) in beer.
Ok so is the solution not to stir the mash? I get what everyone is saying about HSA, I just don't see how it is avoidable, at least to a certain extent.
Especially when batch sparging, although i can see minimizing HSA with fly sparging.
Still though, once you mash in and stir isnt the damage done? do you guys not stir the mash?
Not disputing science, nor am I trying to argue. I fully admit that I am nowhere near an expert on the topic.
I'm just wondering how much it really matters, and how to avoid it.
In a homebrew setting, you would have to be very sloppy for HSA to matter. In fact, total lack of HSA has been shown to cause haze and colloidal instability. You will never get rid of all HSA, but as long as you are not going our of your way to splash/aerate your hot wort you should be fine.
Commercial mash tun w/ mash rakes. Are they mashing under CO2? Not that I know of. And it's very common.
I'd be curious what these new discoveries are causing Bamforth to rethink his position.
I'd be curious what these new discoveries are causing Bamforth to rethink his position.
Here is a good read on beer oxidation from George Fix: https://www.morebeer.com/articles/oxidation_in_beer
"Studies have shown that the oxidation of melanoidins and polyphenols is an important consequence of HSA. These oxidized compounds are normally held in check during fermentation by the strong reducing power of yeast metabolism, but during maturation and the initial stage of aging, these compounds undergo a complex series of electron exchanges. The net effect is the oxidation of beer alcohols and the creation of volatile aldehydes. This process is sometimes called “oxidation without molecular oxygen” because these reactions can take place without oxygen being present. The aldehydes produced do not display their presence until a lag period is over (typically 3–4 weeks). This seems to be because of bonds between the aldehydes and natural sulfur compounds from yeast metabolism. These bonds, alas, are temporary. When they are broken, a wide range of flavors appears. All have a grainy astringency associated with them, and metallic undertones are often present. Sherrylike notes have sometimes been identified as well, and this is one flavor note that is commonly attributed to both CSA and HSA.
Unfortunately, these mechanisms do not explain how the all-important 2-nonenal is created, because it has been demonstrated that there is no alcohol relevant to beer that is a precursor to 2-nonenal. Current research points to fatty acids in wort, along with malt-based enzymes such as lipase and lipoxygenase, as being potential precursors. Heat and oxygen stimulate the enzymatically induced creation of the hydroperoxides that are the precursors of 2-nonenal. In any case, oxygen uptake in the brewhouse remains an obvious culprit in the production of staling aldehydes, along with a still-to-be-determined effect from malting."
"Studies have shown that the oxidation of melanoidins and polyphenols is an important consequence of HSA. These oxidized compounds are normally held in check during fermentation by the strong reducing power of yeast metabolism, but during maturation and the initial stage of aging, these compounds undergo a complex series of electron exchanges. The net effect is the oxidation of beer alcohols and the creation of volatile aldehydes. This process is sometimes called “oxidation without molecular oxygen” because these reactions can take place without oxygen being present. The aldehydes produced do not display their presence until a lag period is over (typically 3–4 weeks). This seems to be because of bonds between the aldehydes and natural sulfur compounds from yeast metabolism. These bonds, alas, are temporary. When they are broken, a wide range of flavors appears. All have a grainy astringency associated with them, and metallic undertones are often present. Sherrylike notes have sometimes been identified as well, and this is one flavor note that is commonly attributed to both CSA and HSA.
Unfortunately, these mechanisms do not explain how the all-important 2-nonenal is created, because it has been demonstrated that there is no alcohol relevant to beer that is a precursor to 2-nonenal. Current research points to fatty acids in wort, along with malt-based enzymes such as lipase and lipoxygenase, as being potential precursors. Heat and oxygen stimulate the enzymatically induced creation of the hydroperoxides that are the precursors of 2-nonenal. In any case, oxygen uptake in the brewhouse remains an obvious culprit in the production of staling aldehydes, along with a still-to-be-determined effect from malting."
I've been batch sparging longer than most people and this isn't necessarily good advice. You need to stir thoroughly, but not violently. There's nothing to be gained from doing that. I also run my tubing to the bottom of the kettle and beyond. Preventing splashing is a minor reason. It also in effect starts a siphon that lets your kettle drain faster and more completely.
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Nice tip, I will be doing this from now on!
kombat
Well-Known Member
Why is there wort coming out of your sparge arm???
You fly sparge with water, not wort.
EDIT: Bah, should've read past page 1, Yooper beat me to it.
Well, I really meant to quote, not to advise. I don't stir like crazy, because I am not chasing efficiency, so I don't think I would have run into HSA in the mash.
I never thought of the siphoning when draining. Will have to do this and see if I see a difference. I have let the wort fall from the tubing to the bottom of the BK. I have never detected anything I would attribute to HSA in my beers.
But maybe with a bit more care I can get them even better.
Stirring harder will not increase your efficiency.
Twss
beersk
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I think it definitely can't hurt to try to eliminate O2 from every part of the brewing process except for pitching time.
wobdee
Junior Member
Yes sir!
Personally I believe HSA can be an issue for the homebrewer as I've had batch that suffered from the aftertaste. Mind you I will say mine occurred because I whipped that wort into a frothy mess while cooling. As for HSA during mashing, never had a problem that I could detect.
OP
OP
LKA, that's very reassuring. I normally try to minimize splashing while mashing and sparging. But if I were more even diligent about avoiding splashing and aeration of the wort, I'm sure that I could reduce HSA even more. As Yooper indicated, it would probably benefit those beers that I lager longer.
OP
OP
Lots of good advice and discussion about HSA and wort oxidation. Thanks for all the replies!
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