Coffee Knowledge | The Evolution of Coffee Bean Processing Methods

From coffee fruits to roasted coffee beans, the most important step in the process is the processing of raw beans.

From flowering to maturity, coffee berries are picked when they are bright red and then enter the green bean processing stage.

Ripe coffee berries

The structure of the coffee fruit is that the outermost layer is the pericarp, the inner layer is the pulp, the inner layer is the endocarp, the silverskin, and the innermost layer is the coffee bean.

Coffee fruit structure

The result of coffee bean processing is to take out the coffee beans inside. Although it sounds simple, it is very complicated to do. Because the proper processing process will play a vital role in the formation of coffee flavor. When did the washed method, sun drying method, semi-sun drying method and honey processing method that we often see today appear?

First of all, the earliest and most primitive method is the sun exposure method.

Coffee originated in the Kaffa Forest in Ethiopia. At first, coffee collectors did not pick fresh coffee berries directly from the trees. Instead, they let the sun dehydrate the ripe coffee berries on the branches. When the berries became shriveled and purple-black, they were picked and stored. When they were ready to drink, they were crushed and the coffee beans inside were taken out. This is different from today's sun drying method. Today's sun drying method is to pick the coffee berries from the trees when they are fresh, put them into a water tank to remove the floating beans, and then put the remaining coffee berries on an elevated net bed to dry and dehydrate.

Coffee cherries drying on elevated net beds in Africa

Later, coffee was sold to Europe by Arabs and immediately became popular among Europeans. At the end of the 17th century, the Dutch East India Company successfully planted coffee trees on the island of Java and invented the water washing method in the mid-18th century. The water washing method is to peel the coffee fruit and then soak the seed shell and the sticky pectin on the outside in water. In this way, after fermentation, the sticky pectin layer on the outside of the seed shell can be easily removed.

Washed coffee cherries

However, the biggest disadvantage of the water-washing method is that it consumes too much water, which increases the production costs in some coffee-growing areas that lack water resources.

At the end of the last century, Brazil, the largest coffee producer, invented the semi-washed method (also called the semi-sun drying method), which greatly reduced the consumption of water resources in the green bean processing process. Why is it called the semi-washed method? It shortens the soaking time of coffee berries in water to one hour, so that the pectin outside the seed shell has not completely fallen off. At this time, it is fished out and naturally dried in the sun for dehydration. This saves water and time compared to the traditional washed method, and increases the sweetness and thickness of the coffee.

Later, the semi-washed method was gradually introduced to Central American countries. However, unlike Brazil, which has a dry climate, most Central American countries have a humid climate. Therefore, washing the coffee berries for a short time after peeling them and then drying them in the sun can easily cause sour and rancid tastes. As a result, Panama and Costa Rica began to improve Brazil's semi-washed method and began to use the honey processing method at the beginning of this century.

Honey treatment is to remove the peel and part of the pectin, and then put it directly on the African elevated net bed for drying without washing. According to the proportion of pectin retained, the one with more pectin is called black honey treatment (almost all pectin is retained), the one with less pectin is called yellow honey treatment (less than half of the pectin is retained) and red honey treatment (at least 80% of the pectin is retained).

Green coffee beans with pectin drying

At this point, the four types of coffee bean processing methods that we often come into contact with today are complete. We can see that its evolution is also a gradual improvement process: first the traditional sun-drying method, then the washed method, then the semi-washed method (also called semi-sun-drying method), and then the honey method.

In fact, there are many ways to process raw coffee beans. For example, Kenya, an important producer of fine coffee, uses a processing method called the double fermentation and washed method. Some countries also have red wine processing methods and even cola processing methods.

More processing methods will continue to be shared with you.

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