Green
It is a seed,
not a bean.
Raw coffee smells of hay and tastes of grass. Follow the line down — everything below it is heat.
It is a seed,
01 · Drying
62%
of a roast happens before the bean is coffee at all. First the water has to leave.
02 · Browning
150°C — the sugars turn.
The same reaction that browns bread crust. Every sweet note in the cup is made here.
03 · First crack
196°C — it opens.
The bean's own water flashes to steam and blows it apart. It swells, throws off its skin, and becomes coffee in about four seconds.
Stop near here and you keep the farm — blackcurrant, grapefruit, cane sugar. Every acid the tree grew is still in there, which is the sourness people call brightness.
04 · The crossing
Fruit falls, sugar rises.
Fruit acid — · Browned sugar — · Carbon —
They cross a little after first crack. Before it the cup tastes of fruit; after it, of chocolate. That one swap is the whole difference between a light roast and a dark one.
05 · Second crack
224°C — oil comes out.
The cell walls give way and oil beads on the surface. From here you are tasting the roast, not the farm: cocoa, cedar, pipe smoke.
06 · The counter
So we stop in four places.
The higher it grew, the lighter we take it. Past the last of these it is ash.