The anatomy of a coffee cherry

Coffee is the seed of a fruit. A ripe coffee cherry is usually red, yellow on some varieties, and about a centimetre and a half long. Inside sit two seeds, flat faces towards each other — those two seeds are the green coffee we roast.

From the outside in: the skin, under it the sweetish pulp, then the sticky mucilage that wraps the seed itself. Next comes the parchment — a thin, papery yet hard shell — and inside it the silverskin, which clings tightly to the bean. At the centre, the seed itself: with the germ in its lower part and the centre cut running along its flat face.

Why it is worth knowing: the names of the processing methods are really about which layer comes off when. For a washed coffee the pulp and the mucilage are both removed before drying. For a natural, the seed dries inside the whole fruit. For a honey, part of the mucilage stays on. The parchment is hulled off before shipping — which is why coffee reaches us as bare green beans.

What turns up at roasting: the silverskin. Some of it stays on the bean after hulling, mostly in the crease, and comes loose during the roast — that is the chaff we sieve out at the end. Break a roasted bean in two and you will still find a thin strip of it in the crease.

One seed, not two: in a small share of cherries only one, rounded seed develops. That is a peaberry — not a fault, just rarer.