Ha! Sorry. . . I have a degree in molecular cell biology and chemistry. One of the thesis I wrote dealt with what alcohol does to the body so I had to do a crazy amount of research it.
And you still brew? Sometimes ignorance is bliss!
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The liver is a hell of an organ 
it’s so forgiving.
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Gets more exercise than any other part of my body. Must mean I love it, right? 
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Only organ that can regenerate itself. Makes it cocky. Sometimes you just have to teach your liver who is boss.
If you don’t take it to its limit once in awhile…how do you know it’s in tip top shape?
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HBC, would love your opinion on milk thistle… I work out and supplement and am really seeing some positive change from milk thistle. I think it helps with alcohol too.
I still think fusels are worst offender. I mean, didn’t we all make beer fermented too warm and get killed the next day?!
Please do not EVER apologize for presenting facts in a community of a hobby that is riddled with wives’ tales and hearsay and “it works for me, so it must be true”!
So basically, if one overindulges with the same set of circumstances (bodyweight, pre-drinking hydration, etc.), if one has beer with higher levels of acetaldehyde, the other will low/no acetaldehyde, the acetaldehyde beer will result in feeling worse the next day, yah? Its basically overloading the system with a toxin its trying to process.
As a correction, I do remember Palmer talking about fusels, and it may have been in the context of hangovers. But I remember reading a paper/abstract on the science of hangovers, noting acetaldehyde as one of the major culprits.
edit - Doh! should have waited the two minutes for @pietro’s post!
For sure! I find fusels to be far worse than a bit o’ acetaldehyde. @8BaconBits had a specific question about something JP mentioned in how to brew, though.
That being said, I’ve had some homebrews that had fusels in them, and the headache hit me within an hour. Ghastly stuff! The good thing about acetaldehyde is there’s a decent chance of it being cleaned up by yeast. Once you have fusel, though, it’s there to stay! I’ve heard that it can age out, but honestly, I have not found any specific evidence that this can happen.
To be honest I don’t really know a whole lot about it other than it is suppose to be good at helping detoxify the liver and has some positive effects on the heart. I can’t find any scientific papers on it but honestly, it’s not toxic and if it makes you feel better then I say go for it.
@porkchop is correct again! Yeah fusels are way worse than acetaldehyde for the body.
To answer your first question, yes the person drinking a beer with higher levels of acetaldehyde will be worse off the next day than someone drinking a purer beer if that is the only difference. Water is a pretty big contributor to hangover symptoms as well though. If the person drinking the beer with a higher acetaldehyde content drinks water in-between beers it can help the body fight any symptoms of a hangover because it will cause vasodilation so that the body can get rid of any toxins quicker. Basically you are helping the body flush out the toxins easier.
As far as fusels: The alcohol that humans are able to process easily are ethanols, which only has two carbon molecules. Fusels have more carbon molecules so they are heavier and the body really doesn’t know what to do with it. We have enzymes in our body to break down anything we are suppose to be ingesting but when it comes across something our body is not suppose to have it doesn’t have an enzyme to break it down into useful molecules so the body gets thrown into chaos trying to deal with the new substance. To give you an idea how sensitive the body is when it comes to alcohols: 1 carbon alcohols are methanol and very toxic, 2 carbons are ethanols and if it is the right one can be broken down by the body, 3 carbons are propanol (rubbing alcohols and the like) and can kind of be broken down by the body but with sever side effects and anything 4 carbons or larger we can’t process.
Fusels are made of several different types of alcohol but the most common fusel in brewing are amyl alcohols which contains 8 carbon molecules and has an bit of an oily feel to it. Due to these alcohols being so much heavier than ethanol, they can cause dehydration as your body tries to get rid of them which causes symptoms of a hangover to come on much quicker than purer alcohols. Depending on how much of the fusel alcohols you have in the beer you can start getting handover symptoms while still drinking your second beer! As @porkchop mentioned, the symptoms come on crazy quick. There have also been a few studies on how fusels mess with the body, pointing to fusels disrupting specific protein synthesis and destroy yeast cultures in the intestines, both of which would make you pretty sick the next day.
@HBC, do you know if there is any mechanism for yeast/bacteria to esterify these alcohols in the presence of an organic acid? Fascinating stuff… Curious if there’s a biological pathway for these to be broken down into compounds like isoamyl acetate.
I intentionally made a 1gal beer that I fermented too warm at 76°. I aged it for 4 months and there was absolutely NO change in perceived esters and fuels. I don not find them to age out.
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Yup it’s called Fisher esterification and all it requires is an alcohol, an acid (normally carboxylic acid but in this case enzymes and coenzymes) and heat. When brewing it happens in the yeast cell. The enzyme alcohol acetyl transferase (AAT) and acetyl coenzyme A (aCoA) are used by the yeast cells to turn the alcohols into esters. Whatever alcohol you start with determines what the final ester is so for isoamyl acetate you would just need isoamyl alcohol in solution and the yeast cells should absorb the isoamyl alcohol, use AAT and aCoA to break the isoamyl alcohol down and the yeast will kick out isoamyl acetate and H2O as a byproduct of the reaction. Also, the amount of oxygen the yeast is exposed to will determine how much alcohol is turned into esters because when the yeast is exposed to alcohol it uses up it’s stores of aCoA to form unsaturated fatty acids. Oxygen also makes it harder for fusel alcohols to enter into the yeast cell membrane. Lactic acid bacteria and acetic acid bacteria also can form esters but this is more of a crap shoot I think.
That’s my understanding as well, although I’ve heard it repeated so many times on the internet otherwise. I would imagine that a microbe with different metabolic pathways, such as brett or pedio, may break them down over time.
Thanks! Specifically fusel alcohols, so these can be esterified as well?
Not specifically fusel alcohols but the yeast cells will react in abundance with the precursors alcohols and fusel alcohol of ethyl acetate, isoamyl acetate, isobutyl acetate, ethyl butyrate, 2-phenylethyl acetate and ethyl hexanoate. All but one of those precursor alcohols is a fusel alcohol. They are going to go after the ethanol first because it should be the most abundant but will hit the fusel alcohols also. There are a lot of different esters produced in any given beer solution but due to sensory threshold we only notice a few of the esters.
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Alright, now I see a need fer a new topic all together…. I’m not sure what you’d call, Dr. HBC ? 
Sneezles61
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I have a paper by Dr. Bill Pengally that describes the esterification of fusels. I have had it happen to some of my beers, too.
Follow on question… any thoughts on why esterification stops in the presence of an abundance of a certain acid? For example, butyric acid. It’s fairly well documented that some of this acid can be transformed into ethyl butyrate, but only fairly small amounts. If the level is just above taste threshold, adding brett can often knock it down enough so that it’s no longer detectable. But it seems self-limiting with large amounts of butyric acid, in that some of it will be transformed, but you’ll still have detectable amounts. What causes the cell to stop before all the butyric is consumed?
