What is underripe cherry in coffee?

Underripe cherry is coffee fruit harvested before it has reached full maturity - picked while still green, yellow, or insufficiently developed to have accumulated the sugar, acidity, and flavour precursors that define quality coffee. It is one of the most common and significant quality problems in coffee production, particularly in strip-picked or machine-harvested lots.

Underripe cherries are smaller and denser than fully ripe ones, with lower Brix readings (typically below 18°) and a higher proportion of starches relative to sugars. When processed and roasted, the seeds from underripe cherry produce quaker beans - beans that don't roast properly and remain noticeably lighter than the rest of the batch. In the cup, underripe cherry contributes astringent, grassy, vegetal, or thin flavours that suppress the sweetness and complexity of a lot.

The standard mitigation is selective hand-picking - returning to the same trees multiple times throughout the harvest season and taking only fully ripe cherry on each pass. Where selective picking isn't economically feasible, floating (density sorting in water) and colour sorting at the dry mill can remove some underripe material before export. For buyers, a high proportion of underripe cherry in the raw material is a processing problem that no amount of skill at the dry mill can fully correct.