Treatment of coffee beans: what is coffee washing?

Coffee washing began in the mid-18th century. In the washing process, the pulp of the coffee fruit (red cherry) is first removed, then the residual mucous membrane on the inner pericarp is removed by a fermentation tank, and the beans are washed and dried. The difference between the non-washing method and the water washing method is that the non-washing method is to remove the pulp after drying, while the washing method is to remove the pulp before drying.

The water washing method can remove impurities (stone or garbage, etc.) and defective beans through each step, so the appearance of raw beans is uniform, is generally considered to be of high quality, and the trading price is higher than that of coffee beans refined by natural drying.

However, the more detailed the division of labor, the more procedures for operation and hygiene management, and the higher the risk, so washing is not necessarily equal to high quality. The biggest disadvantage of washed coffee is that coffee beans are prone to the stench of fermentation during fermentation. Some coffee experts point out: "A fermented coffee bean will spoil 50 grams of beans." Beans will be stained with the smell of fermentation, most of which are due to the lack of management and maintenance of the fermentation tank. Soaking the coffee beans with mucous membrane on the endocarp in the fermentation tank for one night can remove the mucous membrane. However, if the microbes in the fermentation tank change, it will cause the coffee beans to be stained with fermented flavor.

In addition, the equipment cost of coffee washing method is high, the washing steps are also quite time-consuming, and the production cost is relatively higher.