Harvesting is one of the most important factors in how coffee tastes. As has been stated, coffee berries do not always ripen uniformly. Therefore, the conscientious grower who wants to get a high price for his coffee will pick the berries selectively; he will go over his trees again and again picking only ripe berries. Where coffee is carelessly harvested, the berries are stripped just once from the tree, ripe, unripe, and overripe all together.
Once it is picked, coffee can be prepared either by the “dry” method which produces what is called “natural” coffee, or by the “wet” method, which produces “washed coffee”. The “dry” method, which is the older, more primitive method, simply involves drying the berries in the sun or in a mechanical dryer, and later stripping the hard, shriveled husk off the bean, either by modern machine or with a grindstone or mortar and pestle.
The wet method removes most of the covering from the bean before it is dried. Since the moist bean is liable to damage if treated roughly, the covering must be removed gingerly, layer by layer. First the skin and pulp are gently stripped off by machine. This leaves the beans covered with a sticky gluey substance, which if removed mechanically, would damage the bean. Instead, the beans are soaked, and natural enzymes literally digest or ferment this slimy layer off the bean. This step is called “fermentation.”
Next, the coffee is gently washed, and finally dried, either by the sun in open terraces, where it is continuously turned and stirred by workers, or in large mechanical driers. This leaves a last thin skin covering the bean, called the “parchment” or “pergamino.” Some coffee is sold and shipped in its parchment cover but most often a last machine called a “huller” is used to remove it before shipping. The huller is also designed to polish the coffee, giving the flinty, dry beans a clean, glossy look especially important to specialty roasters, who sell their coffee in whole bean.
Wet processed coffee is not necessarily better than dry-processed coffee. Wet processed coffees generally bring higher prices in world markets. Such coffees tend to be more finely flavored for several reasons: generally, the better coffees are prepared by the more costly wet method; only ripe cherries are picked for preparation by the wet method whereas coffee produced by the dry method often includes immature and over-ripe cherries; also, allowing the beans to ferment for a short time after the pulp has been removed is said to enhance the flavor. Processed with care, however, natural coffees can be as good or better than washed coffee.
Dry processed arabicas are often used as the base of espresso blends then enhanced with wet processed Arabica for flavor and a small amount of robusta for body. The wet processed Arabica must not be used in too high a proportion for two reasons: their characteristic acidity is heightened in the preparation of espresso coffee, and their consistency is often very hard and tenacious; after grinding, the particles are still highly homogenous. To encourage the development of body in the coffee it is better to have particles of different sizes in the ground coffee, as occurs with the dry-processed arabicas.