Coffee sorting process is divided into several stages, sorting by density, sorting by size and sorting by color. Sorting by density is the best way to separate the damaged, small, immature and other defective beans. There are 3 steps in sorting by density: First, separate the stones from the coffee. Second, the coffee is skinned and the flakes are removed. Lastly, the density of coffee is grouped using densimetric table, ranging from coffee beans that are lighter, less dense and those which are solid.
Next, coffee is sorted by size, shape and grouped by grade. The highest grade is grade 1 with defect level below 5%. For specialty coffee needs to have less than 4% of beans defect. Beans defect will affect the taste and flavors of coffee.
The next process is sorting by color. Color sorting is the hardest and most important of the sorting process. This process can be done manually by hand or machine. However, direct sorting / manual by hands and eyes of the workers is mostly used, because the quality of the coffee is higher than those sorted using machine.
Beans that are defective or incompatible with the standard such as unsuitable size, poor color, presence of insect attacks and other defects will be removed. So that the coffee beans produced is of the best quality.
Although it has been through several stages of sorting process, there’s no coffee beans are absolutely perfect (0% defect). Therefore, roasters will usually do another sorting by themselves to elimate beans that are defected to get optimal taste.