Aged coffee is green coffee held deliberately in warehouses for one to three years before roasting — the opposite of everything else this site recommends.
What happens
Acidity falls away almost entirely. Body deepens and becomes syrupy. Flavours shift towards spice, cedar, tobacco and dried fruit.
The green beans fade from jade to pale gold or brown.
Where it is traditional
Indonesia, particularly aged Java, and India, where the related monsooning process does something similar with humidity.
The practice dates to the era of sailing ships, when coffee arrived in Europe after months in humid holds and buyers came to prefer the result.
Deliberate versus stale
This is the crucial distinction. Aged coffee is stored in controlled conditions and turned regularly. Stale coffee is old roasted coffee, which is simply flat.
Badly stored green coffee is not aged, it is spoiled — woody, papery and unpleasant.
Who likes it
Divisive. It has a devoted following in dark espresso blending and no place in a modern light-roast filter programme.
Brewing it
Espresso or immersion at medium-dark roast.