At what alcohol content does a beverage indefinitely remain 'safe' to drink

Factual Questions
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21

This is a really difficult question to answer because there are a lot of factors and nuance.

First, to address the point above, it is very easy for gross stuff to grow in beer. It might be disgusting enough to make you throw up, but it isn’t an actual pathogen. Human pathogens are much more difficult to grow in beer (but it’s still possible).

Second, there’s a difference between what can survive versus what can grow. It is extremely difficult for human pathogens to actually grow in beer. It is easier for something already existing to survive - the alcohol and other ingredients won’t kill the pathogen, but it inhibits it enough that it won’t grow more. Since beer starts with a long boil that will kill the standard pathogens, it won’t develop any under normal conditions. But if you inoculated the beer with a lethal dose of a pathogen, you might be left with an unsafe beer.

Third, alcohol isn’t the only thing that makes beer, wine and liquor inhospitable to pathogens. The hops in beer and the low pH in all of them also kill or inhibit pathogens. So even with its lower alcohol %, beer is still “safe” long-ish term because of the boil and hops. It’s not indefinite – it certainly could develop a pathogen given the wrong conditions and enough time – but it will be disgustingly undrinkable long before that.

Wine doesn’t have hops and isn’t boiled, but it has more alcohol and lower pH, and I’d also say it will be undrinkable long before it’s dangerous. There are numerous people who have drank 50-100 year old wine, and I’ve heard of many that said the wine was disgusting, but I’ve never heard of someone getting sick from it.

80 proof liquor is going to be indefinitely safe. When you see things about requiring 70% alcohol to sterilize, they’re talking about surface wiping applications, i.e., short-term contact. Long-term exposure to 40% alcohol will do the job. I’m a little skeptical that diluting it down with foul water to 10% or less would make it always safe (liquor already has a higher pH even before dilution), but I suppose it takes care of the edge cases where the water was just slightly bad.

22

And coincidentally, I was just touring a small brewery this weekend and talking to the brewer about inspections and regulatory stuff. He said inspectors are pretty chill because they know the alcohol will kill anything dangerous, so they don’t do a lot of testing of lines and tanks and such. Conversely, the non-alcoholic beer producers have many hoops to jump through during safety inspections.

The brewery still focuses a lot of effort on sterilization and cleanliness (“90% of my time here is cleaning”) because as noted, it’s easier for gross stuff to grow and make the beer taste terrible. But the inspectors’ job is to make sure it’s safe, not that it tastes good.

23

Hops are rather volatile, so most highly hopped beers have a short shelf life, within 6 months is ideal, after a year or so it’s almost certainly past its prime. As you note, it doesn’t become unsafe, just pretty gross. Other beers like stouts can last for a very long time and many can improve with age.

All of this aging is done in a sealed container of course, in the presence of oxygen vinegar can form, especially at higher strength beer and wine ABVs. Of course this might be a desired result, but probably don’t want to drink it straight (though the people who put mystical properties on apple cider vinegar might disagree).