A coffee bean is not a bean; actually it is the seed of the coffee plant. The seed is found inside a red fruit that is called “cherry”. The two most common plants that produce the coffee cherry are Arabica and Canephora (Robusta). The cherry contains two beans that grow against each other. Sometimes, only one bean develops, called a peaberry, such bean has a distinct oval-round shape.
Anatomy of a coffee cherry
The coffee cherry is surround by an external skin or exocarp. When the fruit reaches maturity, it is bright red or yellow (depends on the coffee variety). Beneath it is the mesocarp, which is the flesh of the coffee fruit. It includes the pulp with the sugary and sticky substance referred to as mucilage. A papery layer named the endocarp, commonly known as parchment comes next. The parchment surrounds the cherry; it is the hull that envelops the coffee bean. Inside the parchment, lay the two beans that contain an embryo. A layer of thin membrane generally called silver skin covers each bean separately. During roasting, the silver skin remnants come off as the chaff.