Coffee cherries must be processed soon after harvesting to prevent the pulp from fermenting around the bean. There are two types of processing known as dry and wet processing.
Dry processing is sometimes called "unwashed" or "natural" processing. Cherries are spread outside for 15 to 20 days. The cherries are exposed to the sun and stirred regularly to help them dry evenly. The dried cherries are then hulled by hand or by machine, removing the dried out pulp and parchment. This is the way coffee has been processed for centuries.
The other type of processing is know as wet or "washed" processing. A few hours after the cherries are harvested, the pulp is removed from the cherries. The beans are then washed in a process that involves cycles of fermentation and rinsing. Small amounts of fermentation don't hurt the bean but softens the remaining pulp and skin, making them able to be easily rinsed off. This is a better type of processing because it causes less damage to the bean than dry processing.
Once the coffee beans have been processed, they are sorted by size and looks, then bagged ready for shipment. Coffee beans that don't make the "grade" for export are normally used on a local basis.
The most important step in getting coffee into your cup is the roasting. Roasting coffee is both an art and a science, requiring years of experience and the right type of roasting equipment.
Green coffee beans are roasted at temperatures ranging from 370 to 450 degrees for up to 20 minutes. During this time they lose 18 to 23% of their weight and increase in size by 35 to 60%. They change color from a light straw green color to medium brown or dark brown, depending upon the degree of roast.The bean splits open and brings out the rich aroma of the coffee.
Roasting is merely the "cooking" of the bean. How much the bean is roasted is what is called the degree of roast. The less it is cooked, the "lighter" or "milder" the roast. There are different terms used for the degree of roast. Some use the words Mild - Mild-Medium - Medium - Medium-Dark - Dark.
Today, another common naming of roasting is after countries -- American roast, French roast, Italian roast, Turkish roast. These all go from light to dark, from mild in taste to down-right burnt tasting.