As with everything, the processes used following the harvesting of the coffee beans, will impact on the flavour profile and mouth-feel of the final product. The choice of process may be driven by any number of factors, not least of which is the geographical region in which the beans are processed, that may dictate that cost of processing outweighs the ultimately desired characteristics of the coffee.
It is critical that the coffee cherries are dried correctly because:
- Over-drying will result in fragile coffee beans that are likely to break and not be optimally roasted, which will impact on the flavour; or
- Under-drying which results in coffee cherries with a high moisture content that cannot be effectively stored and are prone to mould and bacterial infections.
The preferred methods of coffee processing are the following:
Natural process: Also known as the unwashed or dry process. Once harvested, the coffee cherries are sorted and sun dried. The length of time in which the coffee cherries are left in the sun may depend on the plantation production cycle, which may result in the coffee cherries being machine dried after a few days of sun-drying. To achieve the objective of removing excess moisture from the coffee cherries, they are spread evenly, raked and collected frequently as they reach the desired state. The coffee cherries may require up to four weeks in the sun before the excess moisture has been removed.
When correctly dried, the natural process results in a smooth and heavy-bodied brew. This is as a result of the fact that the mucilage remains intact.
The mucilage surrounding the bean is composed of natural sugars and alcohol and impacts directly on the sweetness and acidity of the flavour profile of the beans.
Essentially, the washed process entails fermentation and friction. The coffee cherries are soaked in water in fermentation tanks and the beans are essentially squeezed out of the pulp, such that the mucilage is left behind.
The beans are thereafter dried on pre-drying beds in very thin layers to allow maximum exposure to air and sunlight.
The washed process is the preferred process by the majority of specialty coffee producing countries as it ensures a clean, balanced brew with a more consistent fruity flavour that is slightly acidic.
The essential principle, of this environmentally friendly technique lies in handpicking only perfectly ripe coffee cherries. This is achieved by continuously monitoring the sugar content of the coffee cherries during the ripening period.
The freshly picked cherries are sorted, weighed and then pulped in manual or electrical pulpers and then spread out on African beds to dry.
The primary difference between this method and the Washing method is that the mucilage is not removed from the bean, but instead it is left to dry along with the bean, thereby enhancing the flavour.
From a flavour and texture perspective, Honey processing lies firmly between washed and natural coffees as it retains the body and sweetness of a natural coffee blended with the acidity of a washed coffee. Honey coffees deliver an exclusive cup profile, with a clear, sweet body, with fruity top notes and rounded acidity on the aftertaste.