I’m into home craft cocktails, and also considering trying my hand at home distillation. Couple questions:
1) I’m well aware that some plants can have toxic components that can either be extracted by alcohol (more than water) or possibly potentiated by it. I’m interested in trying new, unique plant flavors for some cocktails, either as homemade bitters, vermouths, or tinctures. But I don’t want to unintentionally extract a compound that will poison us, of course!
2) I’m also well aware of the hazards of amateur distillation as happened during Prohibition, notably poisoning from methanol. Can you recommend a guide to avoiding the hazards of unintentionally producing methanol and other hazards in a home-setting? (and yes, I know there are limits on how much you can legally home-distill. I plan on staying well below such levels – think it’s 5 gallons annually?).
Thanks in advance for your help!
I am not sure exactly what you are trying to do, whether it is making an essential oil, distilling wine to make brandy, or just making wine by fermenting fruit, so I will try to cover everything and hope it is not too voluminous:
Why ethanol intensifies flavors
Alcohol electrostatically sticks to many plant flavor and fragrances, pulling them out of the plant, and making them more available to taste buds. Perhaps this is why our marinara sauce tastes better when I dump leftover wine into it.
Water extracts vs. ethanol extracts
There is good science behind why ethanol is used to pull flavor out of plants. Back in grad school across the hall from my lab, I recall the ethnobotanists in the Ireland lab had these impressive flasks, the size of a small child, full of plant material and alcohol which would swirl around for days. They were hoping to fish out of the plants any interesting new therapeutic molecules that would be less accessible from a water based extract, otherwise known as tea. You get different molecules from water and ethanol extracts. Not better or worse, just different. Some molecules are attracted to both water and ethanol and will be found in both types of extracts, so there is some overlap, too.
Flavor molecules (esters and terpenes and more) tend to be more ethanol-soluble than water-soluble. If you aren't afraid of drinking a tea made from a particular plant, I would not worry about the alcoholic extract, either, other than the alcohol content, because too much ethanol is toxic of course. I'm talking about letting a plant sit in a container of alcohol of some kind. I'm also assuming that the plant itself is not toxic, either. Note: I do not recommend consuming concentrated essential oils, which is different. Concentrated extracts from plants can be toxic.
Will ethanol react with a plant molecule and turn it toxic?
Now, to answer one of your questions, you are not going to "potentiate" a plant toxin in an edible plant by adding it to ethanol. Ethanol is not likely to react with a plant compound to create a toxin. I can't think of any examples of a reaction like that right of the bat here--that does not mean there aren't any, but none come to mind. (Let me know, anyone, if they can think of one, please, this is a good trivia question for medicinal chemists!) The most likely transformation ethanol will undergo is oxidize and turn into acetic acid, which is the process that turns wine into vinegar. And acetic acid is far more benign than ethanol.
Extracting a plant toxin with ethanol
Again, we are not talking about distillation, but just soaking a plant in an alcoholic solution: You may, however, be more likely to extract a plant toxin with alcohol present. For example, if you soak sage leaves in ethanol, more of the toxic thujone (which causes brain damage in large amounts so please don't eat sage essential oil) in the sage oil will be free in the extract rather than stuck in the plant material. That just makes thujone more free in the solution, but you would consume this anyway, I assume--either free or in the plant material, and you would get exposed to it either way by digesting it. So, again I think it is a wash--I would not worry about it assuming you are starting with a nontoxic plant.
The concentration of extracted plant molecules depends on the ratio of ethanol to plant, and how long it soaks. As long as you start with a food safe plant, I would be more worried about the ethanol than the plant compounds. I'm assuming you are soaking something like peaches and not poison ivy. Avoid the pits, the stems, and stuff you would not eat anyway. If there are residual pesticides, those will be liberated into the mixture, too.
Toxins plus ethanol is bad usually because your liver can't handle it all
Consuming any toxin along with alcohol makes it more likely to be toxic, because your liver has to deal with too much at once. That's why having lots of alcohol with drugs that are metabolized by the liver, like acetaminophen (paracetamol or Tylenol or APAP), occasionally kills people with acute liver failure. The effect of a toxin plus ethanol can be more than the sum of the two effects in isolation, and you end up with a bad surprise! But that is a different process than alcohol chemically changing the nature of a molecule in your potion.
It's fun to make your own extracts, and cheaper too!
A lot of commercial flavorings that you find in the spice section of the grocery store are expensive, and contain artificial coloring like caramel coloring. I would rather not have to ingest the artificial coloring.
Some also contain just one "keynote" flavor. For example, bananas naturally make an ester called isopentyl acetate, and when you make this in the lab (it's really easy to make without any bananas) your whole lab smells wonderful, like bananas! However, I think our brains prefer the complexity of natural flavors. Isopentyl acetate will do in a pinch for banana flavor, and I am not afraid of the molecule, but I would rather have the complexity that nature makes. It is just more interesting.
So I make my own alcoholic extracts by soaking, say, a cinnamon stick or vanilla bean in some hard liquor, then I usually use a pinch of the liquid in cooking or baking, so the alcohol evaporates when I heat the mixture, leaving most of the flavor behind. These are so potent that a little bit goes a long way. It is easy to overdo it.
how to make an ethanolic plant extract
I sometimes make my own vanilla extract, or clove, or cardamom, etc., by soaking the spice in a hard, flavorless liquor. You strain this, and in no time you have a spice or herbal extract which stays fairly well preserved due to the alcohol. As long as I am using something I would eat anyway, the most toxic thing I worry about in there is generally the ethanol.
But I might suggest leaving it there and not distilling it. Distillates need to be diluted before you use them, and treated carefully, because once distilled, you concentrate natural plant toxins. Also, if you let it evaporate, you might unintentionally concentrate it into something like a distillate.
how to make an essential oil from a plant extract
I also enjoy the process of distillation; it is fascinating and fun. But I do not distill my extracts, I'm way too busy and not sure what I'd do with them anyway. Also, I don't have to worry about concentrating plant toxins.
When you distill an extract, you are concentrating volatile plant molecules. ("Volatile" to a chemist means having a low boiling point and evaporating easily; it does not mean explosive necessarily, a common misconception.)
In the old days people just cold-pressed plant material to make extracts, rather like making cold-pressed olive oil. It is faster to use a distillation apparatus. You start heating a pot of plant extract, which could be water based, although an alcoholic extract will liberate more oil-soluble molecules. The low boiling vapors from this go up a tube, (which ideally would have a thermometer stuck in it to monitor the temperature). This leads to a diagonally downward sloping tube called a condenser--typically this tube is cooled with a water jacket--and the vapor condenses in the condenser to drip into a second pot, where it is called the distillate. (There are many variations of distillation that I don't have room to go into here, like fractional distillation, too.)
A typical distillation apparatus
You end up with a concentration of the plant's essential oils in your distillate. I've done this countless times; you go from around 200 mL or more of a mixture down to this potent viscous and frighteningly odiferous little puddle (like 5 mL) of plant essential oil. It is fun to unveil a plant's essence, typically a mixture of small organic molecules like terpenes and esters, this way.
You are correct to worry about the toxicity of essential oils. There are a number of case studies of people being hospitalized and even dying after consuming plant essential oils. Search the National Library of Medicine's Pubmed for "essential oil" and you will uncover countless dry case reports describing some unfortunate soul rushed to the hospital in agony after ingesting one. Some of these people die. You even have to worry about essential oils on the skin, if they are not diluted. They can really burn and irritate the skin.
I sometimes put them in my home made cleaners (they repel bugs and smell nice). I will never forget accidentally getting cinnamon essential oil on my skin and it burned like hell. This natural oil is mostly something called cinnamaldehyde and it is really irritating--its why your mouth rebels if you have sucked on cinnamon candy too long! Plants evolved irritating molecules for a reason, to resist being eaten by bugs, for one thing. I have occasionally experimented adding a drop of one to bath water but I often regret it--even a drop in a bath can really irritate your skin, as nice as they smell.
I NEVER recommend consuming essential oils. Imagine that chemical burn going on in your guts! I even avoid skin care products with plant essences in them like menthol (the main component of peppermint oil) because these mostly just irritate your skin, natural or not.
I don't know how to go through the quarter of a million plant species out there and tell you which ones have safe essential oils and which don't! I know some are particularly worrisome, like sage--the thujone in it can cause brain damage. Most people who use them dilute them first, and then use them externally. Like in a kitchen counter spray.
My parents accepted Christmas cookies from a self-proclaimed herbalist last year, and she proudly said she put essential oils in the cookies. My parents were violently sick for a week after they ate the cookies. My mom went to the emergency room from dangerous dehydration. Do not use essential oils in your cooking.
I wouldn't trust any guide that told you which ones are safe or not, if that is what you are looking for.
I don't think you need to distill the alcoholic extract, although the chemist in me thinks that would be a lot of fun. You will want to worry about blowing yourself up if you use too concentrated ethanol to distill; it is flammable, of course. I have no idea about the amounts that are legal to distill. I just do small demonstrations in labs for students.
I suppose if you do end up with an essential oil you would want to dilute the hell out of it to be on the safe side, like I do with my home made counter cleaner, and of course I don't eat that anyway.
Here's my suggestion: Why not just take some hard liquor and give your plant a good soak in it and strain after a few days? This is an extract.
can you make methanol from ethanol?
Here's the good news: you don't have to worry about creating methanol from ethanol, I am pretty sure! I am not aware of any low-temperature chemical process, not using enzymes, where ethanol (a two carbon alcohol) will turn into methanol (a one carbon alcohol), unless I am missing something! That would really surprise me. You would have to heat the living crap out of it to break that carbon-carbon bond.
As long as you are not fermenting wood at violently high temperatures and low oxygen (called pyrolysis or cracking, and you would know this if you were doing it!) you should not be making methanol in any significant quantity. (If you heat it in the presence of oxygen you will just get carbon dioxide and water. That is known as combustion, or burning. Whoopee.) So relax! Methanol used to be called "wood alcohol" because it used to be made from distilling wood in this process.
Now, an enzyme from some microorganism might be able to do such a thing, but not in appreciable amounts in a fermentation where yeast dominate. I don't know enough about the microbiology of wine fermentation--although I used to make wine--to know that particular biochemical process. I seem to think it is the action of a bacterium rather than a yeast.
Congeners formed during fermentation
I know that small amounts of "congeners" are made during fermentation, and these include small molecules like methanol, acetaldehyde, and acetone. Yes, methanol is toxic, and the other congeners are quite irritating and toxic in larger doses than methanol, but my impression is that these congeners are produced in very small amounts during wine fermentation. Some speculate they are part of why some wines cause headache and have off flavors. I am sure the ethanol does not help, either, when it comes to side effects.
These nasty little congeners are present in such small amounts that you only have to worry about concentrating them if you are distilling your wine, the process used to make brandy.
the toxicity of methanol
I think the methanol used during Prohibition was because people couldn't get their hands on ethanol. It was cheaper, made from wood, and added to ethanol prevent people from drinking ethanol. We still have "denatured" alcohol today, what is typically used in labs; it has methanol added to it to prevent abuse. Yes, methanol is nasty bad and makes you blind and is really poisonous. It gets metabolized to formate, an oxidized form of formaldehyde. (Learn why formaldehyde is toxic here.) Of course, ethanol is poisonous too. Just less so.
the toxicity of ethanol
"The dose makes the poison"! And everything is poisonous, it just depends on the amount.
Once upon a time, small quantities of ethanol was thought to be healthy, mainly for the heart, because it increases good cholesterol, or HDL. But that notion has changed. New, better studies appear to show this benefit is outweighed by the risk of cancer and liver damage. That's why, many years ago, I've stopped drinking, except on occasional special events with friends. My sleep is now AMAZING and I wouldn't give that up for the world.
Alcohol definitely increases the risk of cancer. Even small amounts may do this, in particular for women, according to the best data so far.
Even if you are not worried about cancer, it is a non-nutritive sugar, and excess promotes diabetes and liver disease, another current epidemic. If you are not sure if you are drinking too much, the next time you have a standard medical blood test, which everyone should do once a year at least, look at your liver enzymes. If they are elevated, that is a sign that your liver cells are dying, and spewing their enzymes into your blood. It means something is damaging your liver.
I hope I don't come across too much as sounding like your mother here and did not ramble too much. Have fun playing with your potions! Let me know if you have any more specific questions in the future.
Hey Holly – Wow – thanks for the quick and lengthy response!
Just a couple clarifications. I’m not looking to make essential oils, just using alcohol to extract interesting flavors. For example, I use Serrano or jalapeño chiles to make chile (capsaicin)-infused tequila.
Re: distillation, I’m not going to further distill any extracts. Rather, I was thinking of trying making, say, homemade peach brandy, eau de vie, or similar.
So what I’m wondering is, what are the risks of trying to make an ethanol-based liquor at home, from scratch, using an energy/sugar source, yeast, etc., and unintentionally making toxic congeners or by products such as methanol in the process..?? I realize I’m not going to start with ethanol already and accidentally turn it into methanol. What my concern is, starting with a non-alcoholic mixture, and winding up with *several* alcohols in the product, rather than *only* ethanol. Does that make sense..? Hope I’m explaining this clearly…
I’m assuming that if an herb is safe to eat, that an alcohol extract from same will also be safe. But am I right to believe that?
Dear L. S.,
I think you are safe there! You aren't concentrating anything if you are not distilling it--it is still diluted by the volume of alcohol that you add. The reason the sage oil is toxic is because it is concentrated. Of course, the dose makes the poison--the more you consume of anything the more likely it will hurt you. If you make a super concentrated extract it may be so strong as to be unpalatable, so that will naturally protect you from consuming too much of it.
BTW, I recently drank a jalapeno-infused tequila for a margarita in Portland, Oregon, and it was awesome.
You aren't making brandy if you are not distilling
One further clarification--I did a bit of skimming around on the internet and it seems that some people are confusing distillation with wine making. They describe the process of making fruit wine but are incorrectly calling it "brandy", which adds to the confusion. It sounds to me like you are interested in wine making, not brandy making.
Wine making is just adding some source of sugar, like fruit, grapes, raisins, etc. to yeast, which ferment the sugar and turn it into ethanol and carbon dioxide. This is not distillation.
Distillation is required to turn this into brandy, or "brandywine" which comes from "burnt wine". This involves heating the wine, in a pot, and allowing the vapors, which are enriched in alcohol, to travel up a tube, called a condenser. The vapors condense in the tube and drip into a second pot, where it is called the distillate, and that would be the brandy.
More on congeners and how to prevent and remove them
Congeners are small molecular weight molecules (aldehydes, ketones and other alcohols including methanol), that are minor byproducts of fermentation, and may contribute to off flavors and hangover symptoms. Fermenting at low temperatures helps prevent their formation. Also, avoid reactive surfaces like metals; ideally use glass. As long as you don't distill your mixture you don't have to worry about concentrating congeners. (If you are distilling, you might want investigate using a "slobber box"--a small trap that takes the first distillate and concentrates these congeners prior to allowing the rest of the condensate to flow into a second distillation flask.)
You may already know all this! If all you are doing is making your own fruit wine, you are pretty safe. The worst thing that might happen is you get a bug in it and it gets moldy, or you get oxygen in, and it turns into vinegar (I once made tons of really expensive pomegranate vinegar by accident that way and I was not happy. It went on a lot of salads.) The solution is to keep the pH low, or acidic, and use an air lock of some kind.
One more question:
So the examples of poisonings during Prohibition are people trying to make purified ethanol from “denatured alcohol” (aka, ethanol ‘contaminated’ with methanol, etc.), right? *Not* people accidentally producing methanol from normal distillation processes that started with fruits, grains, honey, or other food products and added yeast, etc., correct?
You bet, methanol is deliberately added to "denatured" ethanol to prevent people from abusing it. It is not naturally made during yeast fermentation in any significant quantity that you have to worry about. Worry more about the ethanol.