Coffee beans: exploring their mysterious structure

The origin of coffee beans

Coffee beans are seeds from the coffee tree, which grows in tropical regions. The earliest records of coffee beans date back to the 15th century AD, when Arabs began to use these mysterious seeds to make beverages. Over time, coffee gradually spread to other regions and became one of the most popular drinks in the world.

The appearance of coffee beans

A typical coffee bean is usually oval or flat in shape. They have a smooth and hard surface and are covered with a brown or black skin. This skin is called the "pericarp", and underneath it is a sticky substance called the "pulp".

Dissecting a coffee bean

When we open a ripe coffee cherry, we can see that it contains two important parts: the kernel and the germ. The kernel is what we see and buy in its original state "after shelling". The germ is the seed of the plant, which has the potential to germinate.

The structure of coffee beans

A coffee bean is made up of multiple tissues and chemicals. The outermost layer is the pericarp, which is mainly composed of cellulose and hemicellulose. The pulp is rich in sugars and water, and gives the coffee bean its special flavor characteristics. The kernel contains two relatively small but very important parts: the endosperm and the navel.

Endosperm

The endosperm is the largest and most dominant part of the coffee bean, accounting for more than 70% of the volume of the entire bean. It stores a lot of energy and provides nutrients to the seedling to support its growth process.

Umbilical cord

The navel is located at the end of the endosperm and is connected to the pulp through a tiny hole. This hole is called the "oxidation crack", which is released when we roast or brew and forms a gas emission sound. The "oxidation crack" is also an important sign to determine whether carbon dioxide is produced during the roasting process of coffee beans.

Changes in coffee beans

When coffee cherries ripen and are picked, the kernels go through a series of changes. First, the skin and pulp are removed, leaving the unprocessed coffee beans. Then, the beans go through a process called fermentation and washing to remove the surface of the endosperm. Finally, during the roasting process, the coffee beans are dehydrated and shelled by the heat, gradually turning into the brown or black color we are familiar with.

in conclusion

By exploring the structure of coffee beans, we can better understand how they are formed and affect the flavor of the final drink. From appearance to internal structure, each part plays a key role at different stages. Therefore, when enjoying a cup of delicious and fragrant coffee, please remember to appreciate the efforts behind these mysterious and delicate structures.