Physical properties of coffee beans

Coffee is the roasted kernel of the coffee cherry.  Each coffee bean is actually the seed of a coffee cherry, the fruit of the coffee tree.

In the coffee process, first the fruit flesh (pulp and parchmentlike hull) is removed, and then the kernel is dried, resulting in green coffee beans.

A typical coffee bean has the shape of a half ellipsoid with well rounded edges.  It contains about 12% of water and most of this is lost in the early stage of roasting, followed by a loss of up to 8% of the dry bean material.

The green coffee bean has a very tight structure where less than 7% of its pore volume has a diameter of 10 nm or more.

The two coffee beans are covered by a thin parchmentlike hull, which is further surrounded by pulp.
Physical properties of coffee beans