Introduction to the treatment of raw coffee beans-tanning method

Sun treatment will first identify sunken beans in the sink, that is, ripe or half-ripe beans are spread in the drying farm for natural drying. The specific time depends on the local climatic conditions, which usually takes two to four weeks. When the moisture of the coffee bean is reduced to 12%, then use a sheller to grind off the hard pulp and silver skin.

The sun treatment has a very high requirement on the climate, and if you encounter a rainy day in the sun, it will make the beans moist and moldy. When drying raw beans in the sun, the color is yellow, and the center will be brown after baking, rather than the white of washed beans. Sun beans have relatively better sweetness and mellow thickness, while less sour taste, but the quality is more unstable, there will be greater fluctuations. Due to the low cost of tanning, it is widely used not only in Ethiopia and Yemen, but also in Robbins grown in Africa and Indonesia.

1. Select beans: put freshly harvested coffee beans in the sink, ripe beans will sink, while unripe and overripe beans will float up and can be removed.

2. Drying: put the selected ripeness on the square for 5-6 days until it is fully dry. At this time, the surface of the raw bean turned dark brown and the moisture content was 13%.

3, shelling: after drying, the unbeautiful skin becomes fragile and falls off easily, which can be removed mechanically. Farms run by enterprises are all shelled by themselves, while small farms are handed over to the processing center for processing.

4. Selection and classification: enterprise farms will identify defective beans manually or mechanically, and select them. The manual selection method uses a transmission belt of about 1 meter, and several female workers sitting on both sides visually select bad beans. In some good farms, they are even selected several times until no defective beans are seen. The mechanical selection method uses mechanical discrimination to remove defective beans, followed by the classification process, which divides coffee beans into several quality grades according to the established criteria. Good coffee enters the selected coffee market, while poor coffee flows into the commercial coffee market.

5. Polishing: shelling can only remove the unattractive layer of beans. At this time, the silver film is still preserved in the outer layer of the seed, and the film must be mechanically ground.