Reading a roast: what the colour actually tells you

Colour is the first thing anyone judges a roast by, and it is the last thing we look at. A bean can reach the same reading on a meter by two completely different routes, and those two routes do not taste alike.

Colour is an outcome, not a control

Roast colour records how much of the sugar and protein in the bean has browned. It says nothing about how long that browning took — and time is where the flavour is decided. Two lots pulled at the same colour, one developed over ninety seconds after first crack and one over two and a half minutes, will read identically on a meter and split a cupping table in half.

The longer development builds body and sweetness and sands the sharper acids down. The shorter one keeps the acidity intact and the aromatics bright, at the cost of a thinner middle. Neither is wrong. But you cannot choose between them by looking.

What we profile against

We log charge temperature, the turning point, the time and temperature at first crack, and development time as a share of the total roast. Colour comes last — as a check that this batch matched the one before it, never as the target itself.

If the colour is right and the curve is wrong, the coffee is wrong.

It is a slower way to work and it makes for duller photographs. It also means the bag you open in week three tastes like the sample that made us buy the lot.