After the country of origin and roast, what is the next most important characteristic of gourmet coffee?
Whether the coffee beans off the tree were dry processed or wet processed.
It impacts taste in a big way, and can make the difference between you liking a coffee or not.
Both are techniques used in preparing and drying the beans just after they're picked.
So what are they exactly?
Dry processing is the oldest method. It means placing the coffee cherry fruit in the sun to dry. In Ethiopia, India and Kenya it can be as simple as placing the coffees on sheets on the ground to dry. In Colombia, Brazil and Costa Rica it may mean dispersing the coffee fruit in buildings that look like sunhouses, either covered by glass or fabric screens to dry.
What kind of taste does dry processing give? A slight wildness. A little extra tartness. An uneveness, a little randomness to the taste. This is why earthier coffees are dry processed. (That and the fact that it is less expensive than wet processing). If the coffee cherries aren't dried fast enough there will be a slight rottenness to the coffee. In poor grade coffees, there's also a slight chance of dirt granules or rocks. Of course those are poor quality coffees that none of our roasters would carry! I've been through probably 500 pounds of dry processed coffee and haven't seen a single dirt granule or rocks.
Wet processing is when the coffee cherries are floated in a vat of water. The bad cherries drop to the bottom and area easily removed. (This isn't the case in dry processed coffee where bad cherries have to be identified by hand). They coffee fruit is quickly hulled and the fruit removed.
What kind of taste does wet processing give? A clean cup without the wildness. Wet processing really complements the cleanness and brightness of coffees from places like Colombia, Guatemala, Costa Rica, Honduras and Hawaii, among others. That's where you want floral tastes, acidity, brightness, high notes -- that might be covered by the wildness of dry processing.
So why doesn't everyone wet process? Because sometimes you want the extra wildness to go with the earthiness of a coffee from Ethiopia, Kenya, Sumatra, Papua New Guinea, or Bali. Because dry processing doesn't require the specialized equipment that wet processing does. So it is cheaper for small farmers to enter the coffee business with dry processing.
Personally I like earthy, wild, uneven coffee. It's the same reason I drink ales like Guinness and Sam Adams rather than pilsners like Coors and Budweiser. That's a good analogy for it: dry processed coffees have a touch of ale to them but wet processed coffees are cleaner and clearer like Budweiser out of the can.
It's all up to you to experiment and try these coffees.