Basic knowledge of coffee processing and identification of coffee beans

Drying method

Drying is a way to prepare coffee beans for the roasting process. It is the cheapest, simplest and most traditional coffee bean processing method. When processing, the harvested fruit should be spread on the cement floor, brick floor or straw mat. Ideally, the fruits should be raked flat in the sun and at regular intervals to prevent fermentation. After about 4 weeks, the water content of each fruit will drop to about 12%, when the fruit is dry. At the same time, we should pay attention to the coffee beans should not be too dry, otherwise it is easy to be damaged in the next stage, that is, shelling. On the other hand, coffee beans that are not sufficiently dried are also vulnerable. The next step is to store the dried fruit in the cellar for a while. During this period, the water in fresh coffee beans continues to evaporate.

Wet treatment method

Most Arabica coffee beans are processed by wet treatment. The wet treatment process requires more capital investment and more energy, but this method helps to ensure the quality of coffee beans and reduce damage. In the wet treatment, the pulp is immediately separated from the coffee beans, and the separated peel and pulp are washed off with water. After that, it begins to ferment and uses the enzyme to separate the slippery glue that covers the inner pericarp. Coffee beans are stored in a fermentor for about 12 to 36 hours, which is mainly determined by the surrounding temperature, the thickness of the glue and the enzymes. When this process is completed, the endocarp around the coffee beans is no longer slippery but has a pebble-like feel. Quality control is essential to prevent coffee tofu from rotting throughout the wet treatment, because even one rotten coffee bean can damage all coffee beans. For this reason, the equipment used must be cleaned every day to ensure that no impurities are left before the next round of processing.

The formation of "parchment coffee beans"

After the wet treatment, the coffee beans are still preserved in the inner pericarp, which still contains about 15% water. The peel must be dried until the moisture content is about 11% to ensure that the coffee beans are stored in a stable and safe environment. Water content is critical, because if Arabica beans are overdried to a moisture content of 10%, they will lose their original turquoise and their quality will decline.

Larger plantations or mechanical dryers are used where Rain Water may destroy the drying process, coffee beans are placed in an air-conditioning box and the dry wind blows on the surface of the coffee beans. The drying process can also be done by the sun, and coffee beans should be turned regularly to ensure complete dryness, a process that takes 12 to 15 days. The most important thing is that the endocarp should not be cracked. If the sun is too strong, the coffee beans must be covered. At this point, the whole process is completed. Because the endocarp of coffee beans looks like parchment, coffee beans have become known as "parchment coffee beans". In general, coffee beans are kept in this form until the eve of export.

Grinding or shelling

Coffee beans should be ground before they are exported, that is, the endocarp of Arabian and Robbite coffee beans to be sold should be removed. The residual shell of coffee beans after removal and cleaning of endocarp and drying process is also known as peeling or peeling. It is more difficult to remove the endocarp of coffee beans during wet treatment than during drying, so different shelling machines are needed. "parchment coffee beans" are usually rubbed and shelled at Smoot. The machine is equipped with a rotating body with a screw, which rotates in a box with a screw, while the screw rotates in the opposite direction. When the coffee bean is driven along the rotation, the endocarp is peeled off the coffee bean. Because the rotating body rotates relatively slowly, it produces less heat than other types of shelling machines.

Classification and classification

Coffee beans are graded first by size and then by density. With two exceptions, all coffee beans have a considerable size and the same proportion, with flat on one side and semi-oval on the other. The special cases are pea-shaped coffee beans that tend to be more oval in shape and giant coffee beans with large particles (that is, Marragol peel coffee beans). The prices of these two kinds of coffee beans are always higher. Generally speaking, large coffee beans can produce better coffee. The way to determine the size of coffee beans is to let them go through a sieve. But even so, there may be weight differences between coffee beans of the same size, and coffee beans that have to be removed, bad, crumpled beans will still remain. The next step is to sort these coffee beans. Remove the rotten and black ones. Coffee beans that are sour and overfermented or unshelled. This process depends on eyesight, putting the beans on a moving belt to check.

Coffee beans are graded in different countries according to different grading systems. Some of them, like those commonly used in Haiti, are overly complex and ineffective: the sorting devices used in Brazil, despite their complex structure, are indeed necessary. Overall, there are six export levels, the highest of which is SHB (strictly hard bean), or Highland Coffee beans, which are produced in highlands no less than 400m above sea level.

All coffee beans must be evaluated before they are purchased. The usual practice is to buy coffee beans for self-baking instead of roasting coffee beans that have already been roasted in the place of production. The main reason is that once the coffee beans are roasted, their shelf life will be short. The second reason is that most retailers in America and Europe like to buy coffee beans directly from local roasters so that they can better control the quality of their coffee.