There are four common processing methods for green coffee beans:
- Sun exposure treatment method. (Also called natural drying method)
- Washing method.
- Semi-washing method (also called honey treatment method)
- Sumatra wet planing method. (One of Indonesia’s unique processing methods)
1 Insolation treatment
After the fruit is picked, the sun drying process begins without treatment. This is the oldest treatment method in existence. The drying process usually lasts about 4 weeks. The processing method must be very rigorous to ensure that the coffee does not lose any flavor. The natural sun method requires the local climate to be extremely dry. In some areas, people use dryers to assist in the drying process of coffee berries (the hot air from the dryer can speed up the drying process and help people control the degree of drying).
Sun-dried beans have a complete natural mellow taste, a mellow and gentle aroma, more gums (more viscous), outstanding mellowness and sweetness, and low acidity. (Representative flavors include sauce, choking, high smooth body)
2 Washing and fermentation
It’s used to remove the skin, pulp, and mucous membranes. Farms that use the washing method must build a washing tank and be able to introduce an endless stream of running water.
When processing, put the mellow beans into the pool and push them back and forth, using the friction of the beans and the force of running water to wash the coffee beans until they are smooth and clean. After washing, at this time, the coffee beans are still wrapped in the inner peel, with a moisture content of 50%. They must be dried to reduce the moisture content to 12%, otherwise, they will continue to mellow and become moldy. The better treatment method is to use the sun to dry, which takes 1 to 3 weeks. (Washed beans are very popular because they are of good quality and selling well)
The washing method has a good or low alcohol taste, high aroma, and lively sour taste.
More representative taste; citrus, fruity aroma. Citrus acid.
3 Semi-water washing method (honey treatment method)
The coffee fruit must be removed in the sink first, and then use a machine to remove the peel, pulp, and gelatinous layer, and wash it in water for 1 hour. Because the soaking time is not very long, all the pectin in the coffee pulp is not easy to be removed, and there is still some on the pulp. Residual pectin, at this time, put the wet dada coffee beans in the drying field and dry them flat. It is best to use an African elevated net bed to dry because the ventilation effect is good.
(After Brazil invented the semi-water washing method, it was transmitted to China and the United States, and it was removed directly with a machine, without touching a drop of water)
(It will be called the honey processing method later) (This is also the difference between other countries and Brazil.
The overall flavor highlights the sweetness and fruity notes of pectin. The taste is very close to the sweetness of mango, longan, hazelnut, and honey. The coffee's mellowness is solid, and the acidity is relatively low and smooth.
4 Sumatra wet planing method
The difference between the Sumatran wet planing method and the general processing method of sun-dried, washed, or honey-treated coffee beans are that the coffee beans are generally dehydrated first to harden the body of the coffee beans and remove the shells.
In the wet planing method, when the coffee beans are half-soft and half-hard, and the water content is 30%-50%, the bean husks are directly shaved off, and the roasting process is carried out directly, which can greatly reduce the drying and dehydration time of the coffee beans.
(Mainly because the weather in Sumatra is humid, drying and dehydrating coffee beans is a waste of time, so this method of treatment was added)
The processing method is to peel the coffee beans first, wash them in a sink, pick out the defective beans, then take out the coffee beans and put them in a bag for dry fermentation for several hours, and then directly explode them. You're done in about two days!
In terms of flavor; it has a high mellowness, with obvious caramel and fruit aromas, slightly woody and herbal flavors. (Representative-Mandheling Coffee) This is the regional beauty of Sumatra.
1 What is dehydration?
Generally refers to the roasting process below 170 degrees. The dehydration time required for different roasting appliances is different, but it is usually best to control it at 5 to 8 minutes. It mainly depends on the moisture content of the coffee beans (generally, the moisture content of new beans is a little more. Extend the dehydration time)
2 What is temperature climbing?
Usually, the temperature climbing speed of baking is controlled between 7 and 14 degrees. This is related to the control of firepower. The better temperature climbing speed is controlled at about 10 degrees. The temperature climbing speed is different from the moisture content of the beans. (Generally refers to the speed of temperature rise)
Hard beans and seasonal beans (new beans with more water content, 12%-14%) should be slow to climb temperature and the dehydration time should be prolonged, soft beans or old beans in the coming year (about 12% lower in water content) should be fast in temperature climb and dehydration Time becomes shorter.
3 What is the smoke exhaust?
The amount of smoke exhausted by roasting starts to be obvious at about 180 degrees, the amount of smoke from the first burst becomes larger, and it reaches the maximum after the second burst. (The deeper the baking degree, the greater the amount of smoke) At this time, the air door should be fully opened to avoid and reduce the smoke of roasted beans. The smell is attached.
4 What is taxiing?
This is what many baking beginners ask and want to know about. In fact, the sliding action is to cool down or turn off the fire and use the temperature of the boiler to continue roasting the beans.
During the whole roasting process, the beans are absorbing heat. Only the first and second bursts are exothermic actions. During these two stages, it is best not to increase the fire to bake, otherwise, the beans will easily feel spicy.
Sliding emphasizes that when the fire is turned off, the residual temperature of the boiler and the temperature generated by the heat of the beans during the bursting period are used to allow the roasted beans to continue and slowly roast.