How coffee is made

A tonne of fresh coffee cherries yields only about 200 kilograms of green beans.

stations: 8
things upstream: 2
raw sources: 2
step from the ground: 1

The short version

Coffee beans are the seeds inside red cherries. Pickers harvest the cherries, mills strip away the fruit and dry the seeds, and a hulling machine removes the last papery layers. The green beans are then roasted in a spinning drum until they swell, crack and brown, cooled quickly, and ground and packed.

Pick the ripe cherries

About eight months after the cherries appear, they are picked by hand or by machine. Brazil's huge flat fields are mechanized, while most other countries still pick by hand.

Goes in
Coffee cherries
Float away the duds

In the wet process the crop is graded by airflow, screens and water. Light cherries rise and are skimmed off, and heavier ripe ones sink.
Strip off the fruit

A pulper separates the skin and pulp from the seeds. The slimy layer left on the seeds is removed by fermenting it with microbes and rinsing, or by scrubbing it off in a machine.

twelve to thirty-six hours of fermenting

Goes in
Water
Dry them in the sun

Washed coffee leaves the mill soaked with water. It is spread on patios or raised beds, or dried with heated air, until it has fallen to a stable moisture level. About 90 per cent of Brazilian arabica skips washing and is dried inside the whole fruit.

from 53% to 10–12% moisture
Hull and grade the beans

A hulling machine removes the dry parchment or husk, leaving the green bean. The beans are then cleaned, sorted by size and bagged for export.
Roast in a spinning drum

Green beans tumble in a hot drum. Heat starts the browning reactions that create the flavor. Around 175 °C the beans start giving off heat themselves, and at about 196 °C they crackle as they swell. A dark roast reaches the second crack near 224 °C.

beans lose 15 to 18% of their mass
Quench and cool

The beans are dumped out and cooled fast with air or a water mist. A quick cool halts the roasting before the flavor over-develops.
Grind and seal

Beans are packed whole or ground. Roasted coffee gives off carbon dioxide for days, so bags have valves that let the gas out and keep air away.

End of the lineRoasted coffee Next it goes into instant coffee.

Worth repeating

The beans roughly double in volume during roasting, much like popcorn, because steam builds up inside them.
Arabica accounts for almost 60 per cent of world output, down from about 75 per cent in 1965.
Roasted coffee has a typical shelf life of two weeks, while ground coffee goes stale in about 15 minutes.
Roasters usually work near where the coffee will be drunk, since green coffee keeps better than roasted beans.