Coffee beans are actually extracted seeds that come from cherries grown on coffee trees. There are two major categories of coffee trees Coffea Arabica, and Coffea Canephora, which is typically called Robusta. Commercially important, the Robusta variety is more disease resistant than its Arabica cousin. Robusta coffee is typically very affordable and can be found in the majority of supermarket value-coffee offerings. The Arabica tree still grows wild in parts of Ethiopia and it produces coffee that the world fell in love with so long ago. Arabica beans typically exhibit more complex aromas and flavours than Robusta beans making Arabica the bean of choice for speciality coffee appreciators.
Processing the cherry once harvested the cherry must be processed to remove the outer layer of skin and pulp that surrounds the bean. The manner and care taken during this process can enhance the overall experience of the coffee or create flavour flaws in the final product. Some countries will exclusively use on process to produce their coffee while other countries will use a combination of Wet and Dry processed coffees. Countries such as some of the those in Indonesia (including Sumatra and Sulawesi) use a unique process known as Wet Hulling.
The coffee cherries are evenly spread our across a large area and continually raked. The sun and wind gradually dry the cherry until the moisture level is right around 10% of the total bean weight. The beans are then moved to a warehouse for storage. The drying process can take several weeks.
Fresh from picking the cherries are passed through a pulping machine which removes the bean from the pulp. Next the beans are separated by size. Beans are commonly put into water where the heavier, riper beans go to the bottom and the lighter, smaller beans float near the surface. Once separated by size the beans are transported to a fermentation tank. Inside the fermentation tank naturally present enzymes start to eat away the slick, slimy substance called parenchyma that coats the outer layer of the bean.
Once fermentation has completed the bean is rough to the touch and ready for drying. Drying can be accomplished by spreading the beans out and letting the sun do the work or quickly dried in a tumbler reminiscent of modern day clothing dryers. The beans are considered to be ready for sale once the moisture content has reached a level of 10 - 11%. Once dry the outer parchment is easy to remove as there is an air gap between the bean and the parchment.