Does Whiskey Ever Expire?
While it's common knowledge that wine gets better with age, that's not entirely true for all alcohols. You can let wine sit in a cellar for years and it'll develop all kinds of rich, complex flavors, but if you tried to do the same with a bottle of whiskey or brandy, you'd just be wasting your time. Though hard liquors do undergo maturation, this is a carefully monitored process that only happens prior to bottling, as The Spruce Eats explains.
That's because the point of maturation isn't to just let the liquor, such as a whiskey, sit for long periods of time, but rather to alter the raw alcohol itself and change the flavor profile until it's how it should be. As for how the flavor changes, it's through contact with the barrel's wood. Therefore, when the whiskey is no longer in contact with the wood, the maturation stops. So once whiskey is bottled, what does happen? According to BinWise, not much. If left unopened, whiskey has an indefinite shelf life. It won't get better or worse, it'll pretty much remain the same.
Does opened whiskey expire?
Whiskey is meant to be enjoyed over the course of several occasions, which is exactly why the bottle will either come with a screw top, or with a cork that can be easily put in and taken out, much unlike that of a wine bottle, explains Whisky.com. That also means that as soon as you open it, though, the countdown to expiration begins.
Per BinWise, you can actually enjoy opened whiskey for as long as two years, but this timeline depends on how full the bottle is. If the bottle is at least half full, it lasts one to two years, but if it's almost empty, with only a quarter or less whiskey left, it'll expire in about six months.
Basically, the more whiskey in the bottle, the longer it'll last, because less oxygen will have made its way into the bottle. Exposure to oxygen leads to oxidation of liquor, which eventually causes expiration. Exposure to oxygen starts as soon as you open the bottle, but if you leave it sealed, you can keep it for as long as you want without it expiring.