Flotation Sorting

Flotation sorting is one of the most common and effective ways to perform initial quality control on coffee cherries. As soon as the cherries are harvested and brought to the wet mill, they are placed into a large tank filled with water. Because of the differences in density, the cherries will naturally separate into two groups: those that sink and those that float.

What is flotation sorting? It is a density-based separation technique. Healthy, ripe, and dense cherries will sink to the bottom of the tank, while cherries that are under-ripe, damaged, or infested with pests will float to the surface. The floating cherries are then skimmed off and discarded or processed separately as a lower-grade lot, while the sinking cherries are collected for the main, high-quality processing stream.

Why does this matter to the drinker? This simple step is crucial for ensuring that the coffee being processed is of the highest possible quality. By removing defective cherries at the very beginning, the producer prevents them from contributing off-flavors to the final cup. This results in a cleaner, more consistent, and more flavorful coffee. Without flotation sorting, it would be nearly impossible to achieve the level of quality that specialty coffee drinkers expect.

In practice, flotation sorting is a standard procedure in almost all professional wet mills. It is an efficient and cost-effective way to improve the overall quality of a harvest. While it may seem like a minor step, it is a fundamental part of the quality control process that ensures the coffee you drink is free from the defects that would otherwise compromise its flavor. When you enjoy a cup of coffee that is clean and free of harsh or medicinal notes, you are benefiting from the simple but effective power of flotation sorting.