Coffee beans are the seeds from the cherry fruit of a coffee tree. Normally, two seeds develop within a single cherry. The two seeds are situated inside the cherry with their flat sides facing each other and their round sides facing out.
Peaberry coffee beans are a unique type of coffee bean that occurs naturally within the coffee cherry. Unlike regular coffee beans which are flat on one side, peaberries develop as a single, round bean. This happens when only one of the two seeds inside a coffee cherry is pollinated, leading to the growth of a single, round seed. This shape is due to the absence of a second, developed seed to flatten against during development.
Typically, around 5% of all coffee beans harvested are peaberries. They are known for having different roasting characteristics compared to normal beans, which is believed to affect their flavor profile. Peaberry coffee is often described as more brightly acidic, complex in its aromatic ranges, but lighter in body than coffee made from normally shaped beans from the same batch.
This unique occurrence is not specific to any particular variety or region, and peaberries can be found in both Arabica and Robusta species across different coffee-growing regions. They are particularly associated with Tanzanian coffee, although the peaberry variety of Kona coffee has also gained prominence.
The formation of peaberry beans is a natural mutation and not something that can be intentionally cultivated, which adds to their rarity and distinctiveness in the coffee world.