After coffee is harvested, the coffee beans must be separated from the cherries, a process called Milling. It is difficult to remove all the fruit pulp from the bean without harming the quality.

Coffee beans are the seeds of fruits that resemble cherries with a red skin when ripe, calledexocarp, beneath the pulp is the mesocarp, each surrounded by a parchment-like covering the endocarp, lie two beans, flat sides together.

When the fruit is ripe a thin, there is a slimy layer of mucilage surrounding the parchment. Underneath the parchment the beans are covered in another thinner membrane, the silver skin. Each cherry generally contains two coffee beans; if there is only one it assumes a rounder shape and is known as a peaberry.   The Milling process is accomplished via three basic steps cleaning, drying and hulling.   In the cleaning stage the harvested cherries are usually sorted to separate the unripe, overripe and damaged ones and to remove dirt, soil, twigs and leaves.

There are three main milling methods:

  • Natural
  • Natural Pulped
  • Wet

These methods differ in their cleaning and drying processes.