After coffee is harvested, it undergoes a processing method in which the coffee beans are removed from the raw fruit. There are various techniques of processing coffee; each technique impacts the final flavor of the end product.
The most popular methods of coffee processing are mentioned below:
Dry Process: Also known as the unwashed or natural process. In this process, the newly harvested coffee cherries are sorted and sun dried. In some cases depending upon the plantation production, the cherries are machine dried after being in the sun for a few days. To ensure even drying, the cherries are spread evenly and raked regularly throughout the day. It could take up to four weeks in the sun before the cherries are free of excess moisture.
It is important that the cherries are dried to the correct degree because over drying will result in brittle coffee beans that will not produce a good roast. On the other hand, cherries with too much water content cannot be easily stored, because they will be prone to attack from bacteria and fungi.
When done properly, dry processed coffee results in a smooth and heavy bodied brew.
Semi Dry Process: This process results in a brew that is heavy bodied, earthy, and mildly acidic. This is a relatively new method of processing that is commonly used in Brazil and Indonesia. Also known as the "wet hulled" or "semi- washed" process, this process involves wet grinding in which the skin of the coffee cherries are mechanically removed by a pulping machine. Afterwards, the mucilage may be washed off before the coffee beans are dried. In some cases, the mucilage is not washed off and the coffee beans are allowed to sit for a day before being dried.
Wet Process: Generally, the wet process involves washing the pulp of the coffee cherries to reveal the coffee beans. Wet processing is often used to reduce the acidity in gourmet coffees; this results in a balanced coffee with a vibrant and almost fruity essence.
Here are two ways that the wet process method can be done:
- Ferment and wash method: In this process, the pulp is broken down by microbes when the cherries are fermented. The fermentation process breaks down the cellulose in the pulp to release the coffee beans. The cherries are then washed to separate the coffee beans from the pulp.
- Machine assisted wet processing: In this process, the cherries are mechanically scrubbed until they break apart and the coffee beans are released.
After the coffee beans have been separated, they are ready to be dried.