What Impact Does Coffee Bean Silverskin Have on Coffee Flavor? The Role of Coffee Silverskin

Introduction

The silver skin is the final "protective membrane" of coffee beans. Typically, after coffee beans are processed and ready for release from storage, the parchment (endocarp) is removed, leaving only a thin layer of silver skin wrapping the green coffee beans.

We can also find traces of silver skin in some roasted coffee beans. After grinding the coffee, you can still see some white fragments - these are the remaining silver skin. So, does it affect the flavor of coffee?

Why Does Silver Skin Remain on Roasted Coffee Beans?

During the roasting process, the silver skin attached to the surface of coffee beans will fall off. However, some coffee beans shed more completely, while others still have remnants in the crevices, forming a "white line." This is related to the processing method of the coffee beans.

Natural processed coffee beans retain relatively complete silver skin in their green state, so during roasting, the silver skin sheds more completely as whole pieces (though still leaving trace amounts of silver skin fragments). In contrast, washed processed coffee beans have incomplete silver skin in their green state. During roasting, the silver skin sheds in fragments, and some silver skin in the crevices between coffee beans is difficult to remove, forming a "white line" in the roasted beans. Therefore, this characteristic of roasted beans can also be used for preliminary judgment of the coffee bean's processing method.

Left: Natural processed beans, Right: Washed processed beans

Does Silver Skin Affect Coffee Flavor?

In daily brewing of coffee with more silver skin, when the coffee shows astringency and rough texture, it's inevitably blamed on the silver skin. To test whether the remaining silver skin affects coffee flavor, FrontStreet Coffee conducted two comparative experiments.

FrontStreet Coffee used washed processed Kenya Assilia for this experiment, as this bean has more remaining silver skin. One group was ground normally, while the other group had obvious silver skin fragments cleaned after grinding for intuitive comparison. Cupping and pour-over brewing methods were used respectively to compare the impact of silver skin on coffee.

(Cupping is to test the impact of silver skin fragments on coffee flavor by reducing human interference factors! Pour-over brewing is to test what actual impact silver skin has on the coffee we brew in practical operation! This comparison provides a more thorough understanding of the impact of coffee silver skin.)

Through comparison, the silver skin fragments remaining from washed processing are indeed quite numerous

In the flavor feedback from cupping, the two cups showed consistent flavor performance initially - bright lemon acidity, small tomatoes. As the soaking time extended, the cup with silver skin developed subtle ginkgo flavor, with a rough and obstructive texture. In the medium temperature stage, these two cups showed obvious differences in texture.

Meanwhile, FrontStreet Coffee brewed Kenya coffee with and without silver skin fragments using pour-over method. After brewing, the coffee bed of the group with silver skin was covered with silver skin fragments, while the coffee bed of the group without silver skin showed relatively clean coffee particles.

In the flavor feedback from pour-over coffee, the flavor profiles of the two groups couldn't be described as very similar - they were completely identical and basically the same. In terms of texture, there was basically no perceived difference in the high temperature stage. As the temperature decreased, there were also no differential changes in texture.

Conclusion

The silver skin remaining in coffee beans (especially washed beans) does not have significant impact in pour-over brewing, because the brewing time is relatively short, and the amount of silver skin is negligible compared to the whole. Pour-over brewed coffee will not carry undesirable flavors from silver skin. In contrast, extended soaking time can affect the texture of coffee.

Of course, if you're still concerned about these white fragments, you can gently swirl the coffee grounds after grinding. The lighter silver skin will float to the surface, and then you can use an air blower to gently blow away the silver skin fragments from the surface.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473