What is sorting in green coffee processing?

Sorting is the collective term for the quality-control processes used to separate coffee beans by size, density, colour, and defect status at the dry mill. Several distinct steps together determine the final preparation quality of a green coffee lot before export.

The main sorting methods: size sorting (screening) separates beans by physical size using perforated screens; density sorting uses a vibrating table to separate beans by weight-to-volume ratio; colour sorting - by optical machine or hand - removes defective, discoloured, or otherwise aberrant beans.

Together, these processes produce a lot that is more consistent in size, density, and appearance - all of which contribute to more even roasting and a cleaner cup. The degree of sorting applied - the number of passes, whether hand sorting is included, the precision of the machinery - directly determines the defect count and consistency of what a buyer receives. Preparation specifications communicate the level of sorting that has been applied.