What are the white threads in coffee beans?

The white threads are an anomaly in coffee beans, often referred to as "silver skin". Silver skin is a thin membrane on the outside of the coffee bean, similar to a shell or skin. During the coffee growing process, each coffee bean will be covered with this membrane.

Silverskin originates from the internal structure of the coffee fruit. When coffee fruits ripen, they turn red or yellow and two seeds are formed inside - what we call coffee beans. These seeds are surrounded by pulp and shells, which need to be processed after picking to get the coffee we finally drink.

During the processing, the first step is to remove the shell and pulp of the picked fruit. This step is usually done by washing or dry processing. Regardless of the method used, after removing the shell, further cleaning and screening are required to ensure quality.

The white threads are one of the byproducts that appear during the cleaning and screening process. They are mainly composed of silver skin that remains on the surface of the beans and is not completely removed. Although the silver skin has no direct effect on the taste and flavor of the coffee, it may cause some problems during the roasting process.

Roasters usually try to remove white filaments because they burn easily at high temperatures and may cause black spots or off-flavors on the surface of coffee beans. In addition, white filaments may clog the filter of the coffee machine or affect the extraction effect.

To reduce the occurrence of this problem, many coffee farmers and processors take some measures to remove silver skin as much as possible. For example, in the washed process, they can completely remove it from the surface of the beans by repeatedly washing, stirring and screening. Dry processing requires more steps to ensure that the surface of the beans is clean and free of residue.

In short, white filaments are composed of incompletely removed silver skin, which is often seen on the surface of beans during coffee processing. Although it has no direct effect on taste and flavor, it can easily cause some problems at high temperatures. Therefore, during the production and production process, care should be taken to remove it as thoroughly as possible to ensure the quality and taste of the coffee.