What are black beans in green coffee?

Black beans are a primary defect in green coffee - beans whose interior has turned entirely black from fungal, mould, or pest damage. They develop when overripe cherries fall to the ground and decompose before harvest, or when damaged cherry sits too long on the drying bed.

On the SCA grading scale, one fully black bean counts as one full primary defect - the most serious category. Even a small number in a batch can significantly reduce a cupping score, because they contribute harsh, fermented, or putrid off-flavours that are very hard to miss once you're tasting.

They're removed through float separation, optical sorting, and hand sorting. If you're receiving green coffee with unusually high defect counts, black beans are often the primary culprit - and it almost always points to cherry sorting and drying management issues at origin, not anything addressable downstream.