There are several kinds of coffee in the treatment of coffee beans.

In the process of washing, the peel and pulp of the fruit are treated with a special desizing machine and the coffee beans are peeled off. The coffee beans then enter the fermentation tank for fermentation treatment so that the mucous membrane is no longer sticky. The sugars in the mucous membrane are decomposed during fermentation. Depending on the fermentation method, the fermentation time is usually 12 hours to 6 days (some growers use the watering system to ferment coffee beans. This method is called the Kenyan washing method (Kenyan method) and usually lasts for several days). It is extremely important to decide when to stop fermentation. Once the coffee is overfermented, the taste of the coffee will become too sour. Once the sticky material in the mucous membrane is decomposed, it will be washed down with a lot of water. (the waste water from the raw bean treatment process is considered to be the source of pollution in the coffee industry. Today, advanced technologies are being developed in many areas to recycle and filter the waste water produced by this process. Water shampoo was born in the 19th century, also known as "wet processing".

A tightly controlled fermentation process increases the acidity of the coffee and is reflected in the final taste of the coffee. But as long as the coffee is washed immediately after the fermentation process, the taste of the coffee can be improved, and the method with bright sour taste is very common in Brazil. The natural washing method is very similar to the water washing method, except that the natural washing method uses a high-pressure washing machine to remove the mucous membrane of the coffee surface, thus skipping the fermentation process. Several raw coffee processing companies in Brazil and Colombia have patented this method and have become local natural water system processing monopolies. The amount of water used in this method is much lower than that of washing hair, so some people are used to calling it "semi-drying (Semi-Dry)". Because there is no fermentation, coffee beans do not exist (or only have a very low risk of fermentation), and the overall quality of coffee is more constant. Unfortunately, the taste of coffee tends to be flat because it is not fermented. As a result, growers will not use natural washing for ultra-high quality coffee beans. Most raw bean purchasing companies also seldom buy coffee processed by natural washing.