How Do You Know If a Bottle of Port Has Gone Bad?

You've found an old bottle of Port, or left one open longer than you meant to, and you're not sure whether what's in the glass is meant to taste this way or whether something's actually gone wrong.

What normal ageing looks and tastes like

Port that's simply old, rather than spoiled, often shows more brown or amber tones than a younger example of the same style, especially in Tawny and older Vintage Ports. The fruit character softens into dried fruit, nuts, or caramel notes. None of this is a fault. It's exactly what Port is supposed to do over time, and it's often the entire reason people seek out older bottles in the first place.

The actual signs something has genuinely gone wrong

A sharp, vinegar-like smell means the wine has oxidised too far or been affected by bacteria, well beyond the gentle oxidative character Tawny is meant to have. A flat, lifeless taste with none of the expected sweetness or fruit, especially in a wine that should still have both, suggests it's simply past its point of enjoyment. Cloudiness in a wine that isn't an unfiltered Vintage Port (which is expected to throw sediment) can also be a sign something's off, rather than a normal part of ageing.

Does Port actually "go off" the way milk does?

Not usually, no. Because of its high alcohol content, Port is far more resistant to the kind of spoilage that ruins table wine quickly. Most "bad" bottles of Port are simply wines that have faded past their best, rather than genuinely spoiled in a way that would make them unsafe. If in doubt, the alcohol content alone makes it very unlikely to cause any harm, it's more a question of pleasure than safety.

When you're unsure, trust your nose before your eyes. A wine that smells wrong almost always tastes wrong too, and a wine that simply looks a little more amber than you expected has, more often than not, just been quietly doing exactly what Port does best: getting older, patiently, the way it was always going to.