I saw the String cheese post so I thought I'd share my own "slightly beyond best before date" consumable. I used to have two of them that I had found in my attic under some insulation, but the other one froze in my garage and broke open. (No, it did NOT smell pleasant. I'm pretty sure whatever vile liquid is in that thing does not resemble beer in any way, shape, or form.)
It's perched on a flashlight to try and show the sediment that's built up on the bottom of the bottle.
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You know, there are some kinds of beer that are intended to be aged. I have one bottle of a Russian Imperial Stout that I brewd 7 years ago. But the beer you referred in you post is definitely not the aging kind. In fact, it's supposed to be consumed as fresh as possible. A sample with that age have definitely gone bad.
Some beers are bottle conditioned, but generally liquor, wine and beer are aged in barrels and don't continue to mature in the bottle.
Not quite right though. Beers like Dubbel, Trippel and Quad, Barley wine, Russian Imperial Stouts, Acid beers and so on keep maturation when bottled. One can try this experiment: get yourself 2 bottles of Orval, drink one right way and take notes. Than, drink the other one 2 ~ 4 year later. You'll get a completely different beer. For my taste, 2 years is the sweet spot. In fact, the only way to keep the bottled beer to maturate is pasteurization, which is not a good practice taste wise.
Dubbels and Tripels etc are examples of what I said - bottle conditioned. And sure, other beer spoils, but it doesn’t age in a bottle in the same way as it can be aged in a barrel. Spirits like whiskey certainly don’t either since the barrel aging is really about contact with charred wood.