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The Outside of the Plant
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The coffee plant is a shrub belonging to the family of the rubiacae of the Coffea gender. The three best known species are Coffea arábica, Coffea canéphora and Coffea libérica. However, the first two are very much more important and cover 95 per cent of the world production of coffee.
We shall only describe the plant of the Coffea arábica which is the most extended one throughout the world and in our country.
The Coffea arábica is a not too high shrub that reaches a height of 8 to 10 meters when it grows freely, and 2 to 2.5 meters when it is trimmed in plantation to facilitate its maintenance and the fruits’ harvest.
It has one or several trucks from where primary branches grow, which are not renewed, and give birth to the secondary branches that must be trimmed to activate the plant’s fortification.
The leaves are simple, generally opposed in pairs, with two sharp-pointed stipules that are 0.5 cm long. The leaf’s sheet is elliptical and lance-shaped, between 12 and 24 cm long, with a dark green color that is shiny on the upper face and a paler green on the lower, acuminated on the anthers, attenuated on the base and wavy on the margins.
Its flowers are white and fragrant, axillary. They group together by 2 to 12 flowers per axilla. The calyx is between 1 and 2 cm long and green. The corolla has the shape of a long tube that ends opening in five petals between 6 and 12 mm long. It has five, white stamen, inserted in the throat of the tube of the corolla, alternating with the petals. Its period of flowering is brief and is accompanied by a pleasant smell that is a reminder of jazmine perfume. Normally the flowers bloom during the first hours of the morning and remain open all that day. On the second day they begin to wither. From the third day on, the corolla is detached together with the stamen.
The fruit that is born from the fertilized flower’s ovary is a drupe known as a cherry, with a elliptic form, slightly flattened, with a 15 cm diameter. Green at the beginning, the fruit’s color then changes to yellow and lastly, takes on a bright, uniform red color when it reaches its full maturity. On the outside its skin is bright and thick, the exocarpium, that covers a cape of around 2 mm of a tender, sugary pulp that is the mesocarpium or musilage.
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| The Inside of the Cherry |
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The outer part of the fruit, or pericarpium, that covers the seed has three sections: the most external, epicarpium and mesocarpium, commonly called peel and pulp, and the internal, endocarpium, which is the parchment, consisting of a pale yellow cellulose wrapping.
The epicarpium is made up of a sole cape of cells with think walls where there are numerous stomas.
The mesocarpium is made up of parenchyma – rich in sugar – tannins and coloring substances.
The endocarpium or parchment is a thick cape formed by several layers of thick walled cells, fibers that are yellowish and give the parchment its coriacic characteristic from where its name derives.
The outer side of the seed is convex and smooth while the inner side is flat with a longitudinal furrow. The seed is covered by the spermoderma called silver film, formed by several capes of fibrous cells that are translucent with thin walls. This film is removed when polishing the coffee for marketing purposes and there are only remains in the furrow of the inner side. The seed is greatly made up of endosperms whose cells contain starch, oils, sugars, alkaloides like caffeine and other substances. When toasted, deep changes occur in the structure of the seed'’ cells. The most important one of these changes is the formation of aromatic bodies that are freed when the toasted coffee is ground, when only the walls of the cells remain, and giving the commercial product is characteristics of aroma and taste.
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Flower of the coffee plant
Lithography of "Coffea Arábica"
Parts of a coffee plant
engraving in the
“Encyclopedie de
Diderot et d´Alembert
Lithography of "Coffea Arábica"
details of the cherry
Cherry of the coffee tree
before being depulped
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