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.
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.
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.
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?
@HBC I’d love to know more about vasodilation, partly because I was once told (by a physician) that the biggest benefit of alternating alcoholic drinks and water (when out drinking) is simply that you are drinking less alcohol. I thought that once your body entered the state (name escaping me) where it was breaking down alcohol, any water you consume is just going right through you and not helping to hydrate you.
Awesome thread! Someone buy this man a beer. That is fermented at a proper temperature…
My buddy and I aged a bunch of fusel laden brew a long time and fusels remained, so I am in the cannot age them camp too… That said, we had some “hot” beers that aged and esterified quite well. From memory, the fusel beers pushed into the nail polish/chemical/fuel-ish territory, and the hot were rubbing alcohol or strong smelling.
So most chemical reactions are self limited by how many reactants are in solution and how much catalyst is in solution. So if you are using Chemical A + Chemical B to make Chemical C while using Catalyst X to push the reaction, once you run out of either Chem A, Chem B or Catalyst X the reaction stops. Some reactions can also be stopped by temperature changes or if the solution gets too saturated with one of the reactants.
In your example, Butyric acid is a bit of an odd ball because it’s ester Ethyl Butyrate is so volatile, but I’ll get to that in a second. So the reaction for this is Ethonal + Butyric acid <—> Ethyl Butyrate + H20 while using a fatty acids to push the reaction from the left of the equation to the right and is called a condensation reaction. Brett yeast will push the reaction to the right as well because it has the right enzymes to reduce the butyric acid.
So a few factors will limit this reaction I think. Also please note I am just talking about biology and chemistry. I’m still a fairly new brewer compared to everyone on this forum so I may get some of the brewing parts wrong. In several experiments it was found that a molar ration of 1 mole of butyric acid to 10 moles of ethanol at a temperate of 75 degrees Celsius with a suitable amount of catalyst (in this case fatty acids from the yeast) will produce the optimal amount of ethyl butyrate. So what would cause this to stop? Too much ethanol with too little butyric acid would do it. If the optimal ration is 1:10 and you have a ration of 0.5:20 then the reaction will not push forward to form an ester. Also, the temp would have an effect on how much butyric acid is formed along with the yeast used, as well as the amount of fatty acid the yeast can use as a catalyst to push the reaction from an acid to an ester. The last reason is why Brett will be self limiting. From my understanding Brett is used because it has an abundance of the fatty acid to use as a catalyst for the chemical reaction, but this reaction is self limited by the amount of live Brett in solution as well as the amount of fatty acids present. Once the chemical reaction uses up all the catalyst it will be less willing to move from left to right in the chemical formula above. Catalysts are essentially used to make a chemical reaction happen when it doesn’t want to because it is already in equilibrium, so when the catalysts are used up, the chemical reaction wants to stay in equilibrium so the substrates (ethanol and butyric acid) do not react with each other
So something weird about ethyl butyrate that I touched on earlier. It is very volatile. Essentially it doesn’t want to be Ethyl butyrate because ethyl butyrate isn’t a stable molecule so it will undergo something called self hydrolysis, meaning that the hydrogen atoms will remove themselves from the ethyl butyrate. It should remove itself from a beer over time due to this.
I guess you would kinda be drinking less alcohol since you are using your time to drink water as opposed to beer but I think I would disagree with him on that one. The water you are consuming during drinking is acting more to flush your system than to hydrate yourself, but the end result is you stay hydrated (mostly). It’s kinda like when you have the flu you drink liquids to keep your body running as best as possible. The alcohol in beer is a diuretic, similar to caffeine in coffee, both causing your blood vessels to constrict and become smaller. Essentially you are removing water from your circulatory system in order to break down the alcohol/flush out toxins, making your circulatory system work harder to move thicker material through smaller blood vessels. By drinking water you are adding more water to your circulatory system to keep it open and working at peak efficiency. It is also diluting the alcohol in your system by surrounding it with more water, so less alcohol will hit your liver at the same time, and allow you to remove toxins from your liver much quicker since your blood is nice and watered down and running though wide open blood vessels. You will be losing the water you are putting into your system instead of keeping it, but it will be pulling the toxins out of your body as well.
Ha! I should be buying all of you a beer! You guys are making me think about things I never would have though about so I am really learning a lot by answering this.
It sure is the best way! I learned a ridiculous amount writing a couple brewing articles for a local magazine. With your background, sour and wild brewing would probably be right up your alley.
What an incredibly interesting thread. I’ve never studied the science behind beer and alcohol any, but this is great stuff. Following this thread closely. Thanks.
Then look up back to the surface from the neverending whirpool/vortex you just entered
There is also a Brewing Network Sunday Session podcast where they had Chad Yakobsen on (the first time). He is the head brewer @ Crooked Stave and wrote his doctorate thesis on Brettanomyces. Pretty awesome stuff. It inspired a new show on the network called The Sour Hour with the guys from Rare Barrel.
Sneezles61
