The two commercially significant species of coffee beans are Arabica and Robusta beans.
Arabica beans grow best at altitudes over 2,500 feet. This means longer time to mature. This species produces superior quality coffees, which possess the greatest flavour and aromatic characteristics. They typically contain half the caffeine of the Robusta beans. Arabica production represents 80% of the world’s coffee trade, however, only 10% of this meets specialty coffee standards. The Arabica bean provides the strong flavour. The Robusta offers the froth and the caffeine. Most gourmet/premium coffee is produced from 100% Arabica beans.
Processing in coffee production refers to the methods used to transform freshly harvested coffee cherries into dry seeds ready for export. Processing is a crucial step in a coffees journey from seed to cup, and it can have a profound effect on the final flavour of the coffee. The 2 most common processing methods used by producers around the world is either Washed or Natural.
Washed Process - referred to as the Wet Process
In this process freshly harvested coffee cherries are sorted for ripeness, then mechanically depulped.
Most of the fruit is removed during depulping, but some mucilage continues to cling to the seed. The next step, fermentation, naturally breaks down the remaining fruit’s grip on the seed. Fermentation times range from 12 - 36 hours, depending on weather. The coffee is then washed in fresh water to remove the last bits of fruit. Sorting is made easier in that ripe cherries sink, unripe cherries float. Under ripe cherries impact on the quality of the coffee. Next the coffee seed is slowly dried on patios, raised beds, or in mechanical driers until it reaches 10 - 12% moisture.
Finally, the thin protective parchment layer is removed to reveal the raw coffee bean that will eventually be roasted. Many producers of high quality coffee prefers this process in an attempt to reduce defects. It is however more expensive than the other methods of processing and relies heavily on availability of fresh water.
Natural Process - referred to as the Dry Process
In this process freshly harvested coffee cherries are laid out in the sun to dry.
When fully dried the thin parchment layer is removed to reveal the raw coffee bean that will eventually be roasted. This method is more risky and prone to defects, often resulting in tainted flavours.
Naturally processed coffees rely on visual sorting for ripeness in contrast to water sorting in the washed process (ripe cherries sink & unripe cherries float).
Natural coffees tend to have more under ripe beans (known as Quakers) than washed coffees.