Preparing green coffee beans for market is done by removing all the outer layers of the picked berries and is done by two different methods – The wet process and the dry process. The wet processing method is considered the better of the two.
The Wet Method of Coffee Bean Processing
During picking, sticks, leaves, over ripe, unripe and bad cherries are found amongst the harvest. They are sorted and separated when passed through water where the unwanted products will float and the ripe fruit (seeds of the coffee plant) sink to the bottom. The unripe green berries are hard and cannot be pulped. Instead they pass through the coffee bean processing equipment, leaving the pulp (the outer layers of the berry) separated from the beans.
The ‘unproductive’ wet method is done by steeping the beans in coffee fermentation tanks for around a day, but this ferment and wash method but nowadays is usually done by machine.
The beans are then dried in the sun, where they are frequently turned allowing the air to better circulate around them allowing them so that they are evenly dried. Where space is limited, special machines are used for this procedure.
Once dry, a silver skin or husk is left around the bean which is easily removed in the hulling operation, before the market ready crop is shipped overseas.
The Dry Method of Coffee Bean Processing
This is the oldest method of bean processing and produces ‘naturals‘ or unwashed coffee. The whole cherry is laid out to dry in the sun for around 3 – 4 weeks and are turned frequently to ensure thorough drying and to prevent mildew build-up.
Before being dried, the beans are cleaned of soil, leaves, sticks, over-ripe and under-ripe berries.
If left to over-dry, the beans brake up when hulling, as they become brittle and are then classified as defective. And if not dried enough, they can fall victim to bacteria, mildew and even fungus again, rendering them defective. Although this process is not as effective as the wet method, because it is time and labour demanding, the natural coffees age better. The perfect beans are then ready for shipping and to be roasted.