Long before it becomes a coffee bean that is ready to be ground for brewing, the beans must be processed first. One important element in the processing of coffee beans that you need to know, especially for roasters, is processing post-harvest coffee.
Postharvest processing has a very big influence on the physical quality and taste of the coffee. Different post-harvest processes will produce different coffee flavor characteristics, even though the coffee comes from the same type and variety of coffee plants and is grown on the same plantation!
The post-harvest coffee process begins when the coffee is picked from the tree. Generally, the post-harvest coffee process is carried out by farmers, immediately after the coffee fruit is picked. Farmers immediately start the post-harvest process so that the coffee fruit produced does not taste defective (which is caused by taking too long to start the post-harvest processing).
Coffee fruits that have been picked can be processed using four methods (Puslitkoka, 2016): (1) full wash - dry hulling; (2) full wash - wet hulling; (3) semi-wet / natural pulp process; and (4) dry process. The taste profile produced by each of these processing methods will give a different taste and character to each other.
1. Full Wash – Dry Hulling
In general, this processing will remove the skin and flesh of fruit attached to the coffee beans before the drying process. The skin and flesh of the fruit are removed using a machine called a depulper. Then, the seeds are fermented within a span of 24-36 hours to clean up the remnants of the skin and mucus that remains, leaving only the skin of the horn alone. Then, the seeds are dried until the water content reaches 11% - 12?fore finally being put into the huller machine to remove the horn skin.
The coffee flavor character produced from Full Wash - Dry Hulling process has a more clean, light, less fruity character, the body tends to be lighter and the acidity level is higher.
2. Full Wash – Wet Hullings
The stages in this process are the same as the previous processing method, but different during the process of stripping the horn skin. The previous method, the skin of the horn was peeled when the water content reached 11% - 12%, then in this process, the coffee moisture was left up to 30-35?fore peeling again until the shape was truly seed / green bean. After the skin peels off, the seeds are dried in the sun again to dry (water content 11% - 12%).
The coffee flavor characteristic produced in this method has an intense sweetness level, fuller body, and lower acidity level compared to the previous process.
3. Pulp
The Natural Pulp process is usually applied in areas with limited water availability because this process requires only a small amount of water. The initial stages are similar to the full wash process. But the difference is after the coffee fruit is peeled (pulping) the fruit is directly dried in the sun without going through washing and fermentation first. This causes the coffee beans are still covered by mucilage.
The advantages of this processing method can produce coffee with a more chocolaty and caramelly flavor, even scented like honey.
4. Dry Process
This process is also commonly called the Natural Process. This method is the simplest method. After the coffee is harvested and sorted, the coffee is directly dried in the sun until the water content reaches 11% - 12%. The dried beans are then peeled to separate the skin and coffee green beans.
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