Layers of Coffee Fruit and Bean Provide Unique Flavor Qualities
The Layers of a Coffee Fruit
Starting on the outside, a coffee fruit includes the outer skin (known as the exocarp or pericarp), the pulp (or mesocarp), the pectin layer, the parchment (also called the hull or endocarp), the silverskin (also called testa or epidermis) and finally the coffee bean (endosperm).
Endosperm Dominates Coffee Bean Anatomy
Most of the coffee bean itself is comprised of endosperm, which is the tissue that is created near the time of fertilization in most flowering plants. The endosperm surrounds the embryo and supplies nutrition (starch) but may also contain proteins and oils.
In a coffee bean the endosperm caffeine content ranges from about .8 percent to 2.5%, leading to its popularity as a brewed beverage and thus a major cash crop cultivated around the world.
The Pulp and the Silverskin
Beneath the outer skin of the coffee cherry is the fruity pulp, and beneath the pulp is the silverskin. The silverskin is a very thin and fine layer of skin which envelops and adheres tightly to the seed of the fruit which is the coffee bean.
Coffee Bean Processing – Dry and Wet Processing
Dry processing coffee beans involves laying the coffee fruit out in the sun to dry for about two or three weeks while repeatedly turning the beans so they dry evenly. After drying the dried pulp is separated from the coffee beans.
Wet processing involves separating the outer flesh of the coffee fruit from the seed (coffee bean) and soaking the beans in water for one to two days (fermenting) to remove any fruit pulp or residue from the coffee beans. After this the beans are rinsed and dried in the sun or in a drying machine (forced-air drying).
Both methods of coffee processing have their pros and cons, and different effects on the brewed coffee’s tastes and aromas. There are variations on these methods including pulped natural processing and semi-washed processing.
Anatomy of a Coffee Bean continued:
Peaberry Coffee Beans – One Bean Instead of Two
Approximately one percent to seven percent of every coffee crop are peaberry coffee beans which are comprised of one whole coffee bean rather than the typical two half-beans.
Peaberry coffee beans are esteemed for their robust taste which is thought to be due to their higher density than regular beans.
Coffee Plant Varietals Affect Quality of the Bean
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