Can I Accidentally Make Methanol? A Homebrewer's Guide to a Common Fear

From time to time, I see potential brewers ask if they will accidentally make methanol (AKA 'wood alcohol') when foraying into beer production. It's a legitimate fear, fueled by horror stories of people going blind from "bad moonshine." This is because methanol is genuinely dangerous. It is toxic to the human body and can have some very nasty effects if someone is poisoned - ranging from blindness to, in the worst cases, death.

You may have arrived at this page because of the sad story coming out of South Africa during 2020 where a couple died after drinking homebrew. While there are limited facts on this tragic case, we can be confident that methanol from a standard beer homebrew was not the cause. Let's separate the myths from the science.

The Short Answer: No, You Won't Go Blind

First up, the answer to the question is that the ordinary beer home brewing process makes the alcohol called ethanol - not methanol. They have slightly different chemical formulas, and brewer's yeast (Saccharomyces cerevisiae) is a biological factory perfected over millennia to produce ethanol.

So you can't get methanol poisoning from your homebrew, no matter how much extra sugar you add. It's more likely that you will just get blind drunk or meet Darth Vader!!

The Science: Fermentation vs. Distillation

The confusion and fear surrounding methanol comes from a misunderstanding between two very different processes: brewing (fermentation) and distilling.

Fermentation is a biological process. Yeast consumes sugar and produces ethanol and carbon dioxide. While some trace amounts of methanol can be produced, especially in fruit-based fermentations containing pectin, the levels are negligible and far below anything that could cause harm. Commercial fruit juices often contain more methanol than a homebrewed beer.

Distillation is a physical process of separating liquids based on their boiling points. This is where the danger lies. Methanol has a lower boiling point (64.7°C) than ethanol (78.4°C). In a backyard still, when the fermented mash (the "wash") is heated, the methanol vaporizes first. This first part of the distillate, known as the "heads," is highly concentrated with methanol. Inexperienced distillers who fail to discard the heads can indeed create a lethal product. For this reason, home distillation is illegal in most countries. If you are homebrew brewing beer, there's no risk of making a killer brew. Distillation on the other hand... stay away from that unless you've been properly trained.

Methanol Poisoning & Treatment

For educational purposes, it's important to understand what methanol poisoning involves. Methanol toxicity is the result of consuming methanol. The horrific symptoms may include a decreased level of consciousness, poor coordination, vomiting, and abdominal pain. The famous effect of decreased vision or blindness may start as early as twelve hours after exposure.

The blindness is caused by the methanol being metabolized by the body into formic acid, which then has a debilitating and damaging effect on the eye's optic nerve. Fortunately, there is a cure. The sooner the antidote, fomepizole, is administered, the greater the likelihood of a good outcome. Other treatments include dialysis and sodium bicarbonate. This is not medical advice. If you suspect a consumption incident, seek medical assistance immediately.

What About That Old Bottle of Wine?

I saw a query from a gentleman who decided to drink a glass of wine after leaving the bottle open for 2 months. The wine was disgusting, burned his throat, and gave him a headache. He wondered if it had turned into methanol.

It's more than likely that the wine's ethanol had not converted to methanol. Instead, it was exposed to oxygen and Acetobacter, a common airborne bacterium. This bacterium consumes ethanol and produces acetic acid—turning his wine into a vile vinegar!