Dry Method for Coffee Processing Deceptively Simple

There are two ways that coffee beans can be processed: These are known as the wet method and the dry. In this blog installment, we will discuss the dry method.

The dry method is the cheaper process and is often used on the robusta variety of bean; it is normally used for lower grade beans and has a significant impact on the price and quality of the final product. Not only is it cheaper than the wet method, it is also the simplest process to perform. The harvested cherries are spread over a concrete, brick or matting surface, ideally in sunlight, and the cherries are raked over at regular intervals to prevent fermentation. If it rains or the temperature drops, the cherries have to be covered for protection.

After about four weeks, when the moisture content of the cherry will have fallen to about 12 per cent, the cherries are considered dry. At this point the outer shell of the cherry will have become dark brown and brittle, and you you can hear the bean rattle around inside. The drying process is more complicated than it sounds, because it is possible to over-dry the beans. If that happens, the next stage (known as hulling) becomes more difficult, as damage to the bean can take place. On the other hand, if the beans are not sufficiently dry, the beans are more susceptible to fungus.

The dried cherries are then stored in silos, during which time the cherries continue to dry. The dry method produces "naturals" or unwashed coffee. Brazil has recently found some success by using an intermediate method between wet and dry, which has resulted in some beans being termed "semi-washed" or "pulped naturals."

The final step in coffee processing involves removing the last layers of dry skin and remaining fruit residue from the now-dry coffee, as well as cleaning and sorting it (hulling). Hulling is normally done with the help of machines, which can range from simple millstones to sophisticated machines that gently strike the coffee.