So, you found out that a coffee bean looks completely different when it's harvested. I know, we were shocked too.
We only see the end product, the coffee in liquid form, or the bean before it's grounded if that. We hardly see what it looks like before all the processing.
Coffee processing is essentially 'cleaning' and 'stripping' the coffee cherry by getting rid of skin, layers, pulp, mucilage and other unwanted elements.
There are many ways to process a coffee cherry, each to a certain extent, aren’t really chosen, but are instead largely determined by environmental and climate factors of where the coffee is harvested.
Let's breakdown the most common types or processing:
Washed
Natural/ Dry
Honey
Anaerobic
Washed
Washed or wet coffee refers to the process where the coffee bean is separated from the cherry’s pulp and skin before fermentation, while the remaining mucilage is washed off by running water after fermentation and before drying. As mucilage is responsible for most of coffee’s sweetness and body heaviness, washed coffees’ taste tends to be clean, lively, fruity and with a slight fresh acidity, and it is more focused on the actual bean itself, as all the leftover mucilage from the original cherry is removed by the water.
Here is a 5 steps summary of the process
- Sorting. The cherries are picked and sorted to remove any unripe or damaged fruits.
- Pulping. The skin is removed from the bean, generally through specific machinery. At the end of this process, all the layers of the cherry are removed except for the mucilage layer.
- Fermentation. Coffee is now stored into tanks full of water. Fermentation allows for the creation of enzymes which favour the breakdown of the mucilage.
- Wash. The mucilage layer is removed by washing with turbulent water.
- Drying. Coffee beans are now dried either naturally or mechanically (or by a combination of both).
Natural or Dry process
Unlike washed coffee, Natural or Dry processed coffee is dried in the full cherry prior to pulping. For this reason, natural coffees tend to develop more fruity/ berry and fermented/ citrusy flavours along with a heavier body compared to their washed counterpart. Concerning environmental impact, natural processing doesn’t require any water at all. Natural coffees require particular attention during the sorting and drying phase to prevent the cherries from rotting and transmitting funky smells to the beans. Cherries are considered dry once their moisture level reaches 12%.
Honey
The honey coffee process is the most demanding one, and only the ripest cherries can be used for this purpose. Once picked and sorted, these cherries are then pulped mechanically, only leaving a certain amount of mucilage on the beans. Different types of coffee determine the amount of mucilage that is left on. Despite the name, honey processing does not involve any actual honey. The “honey” is in fact created by the mucilage that is not washed off coffee prior to the drying phase, which results in a honey-like texture encasing the beans once drying is complete. Also, in order to dry properly, coffee beans need to be turned every hour for 10 to 15 days to gain the necessary stability. In terms of taste, honey coffee is fruity, sweet and smooth, while acidity is muted.
According to a standard from Costa Rica, depending on the amount of mucilage left on the bean prior to drying honey coffees can be divided into the following categories:
White honey process: 80-100 percent of the mucilage is removed
Yellow honey process 50-75 percent of the mucilage is removed
Red honey process 0-50 percent of the mucilage is removed
Black honey process removal of the least amount of mucilage possible.
Anaerobic
Compared with the ones above, Anaerobic coffee is a relatively new, innovative and experimental processing method. The term Anaerobic refers to the fermentation stage of the process, which happens in total absence of Oxygen. As an experimental method, this process is still in evolution and different growers experiment with different things. The results are unique and exotic flavours, with no two tasting the same. This uniqueness is also possible because this process can be applied to naturals, honeys and washed coffee, as they can all be fermented anaerobically.
Brief explanation of the chemical process:
Beans are placed inside sealed tanks. As the CO2 generated by the fermentation cannot escape the sealed environment, its build up starts progressively pressurizing the tanks. Excess pressure and oxygen are them expelled through release valves. CO2 pressure plays the key role of forcing the juices and sugars naturally present in the cherry into the bean itself. After fermentation is over, coffee is then dried according to one of the above described processes (dried in cherry for natural, in mucilage for honey, or washed and then dried for washed process).
