Processing the Best Coffee Beans
The best coffee beans must be hand-picked regularly and selectively to avoid overripe or the immature. Machine-picking damages the bush.
After picking, processing must begin straight away, or the green coffee beans go sour. The coffee bean is removed from the cherry by one of two methods:
- Dry Method: this is used in water deprived areas and is "natural coffee". The cherry is laid out in the sun to dry, raked over regularly to avoid uneven drying which can cause sourness. Later these are hulled to remove the shrivelled husk. Broken or split beans, which do not roast well and unacceptable to the coffee trade, are removed in grading.
- Wet Method: this is used for better quality coffees, which tend to be grown in mountainous areas where there is more water. The flesh is bruised off the cherry in a pulper or "decorticator", and the berries are soaked in water to soften and loosen the shell - this is "fermentation". This process takes about two days and without careful control the wet beans can rot and go sour. The "washed coffees" are then laid out in the sun to dry, raked over regularly for quicker and more even drying, or are dried in rotating hot air machines. The only remaining sign of the outer shell (the "parchment") is polished off in a huller.
The advantage of the wet method is that the whole bean is maintained, but it is labour intensive and water intensive. "Natural coffees" should not be ignored, because many good coffees like Ethiopian mocha are made this way.