Coffee species and coffee varieties
Coffee is an evergreen plant that grows as a bush or small tree. There are around 90 species of coffee plant around the world, but only a few are relevant to the coffee we drink each day. Biologists assign it to the genus ‘Coffea’, of the Rubiaceae family, which originates in the Kaffa province of Ethiopia.
The bushes of coffee plants grow up to four metres in height and have oval leaves with white racemose blossoms. In each of the plant’s drupes, known as coffee cherries, are two seeds, which we know as coffee beans. Depending on the species of coffee plant, the fruits ripen seven to 11 months after pollination and change colour from green to yellow and then red in that period.
Among the approximately 90 different species of coffee plant, the most commonly used are C. arabica (arabica coffee) and C. canephora (robusta coffee) from Africa. Occasionally, the species C. liberica and C. excelsa are also used for coffee production.
The blossoms of coffee bushes are white and form multiflorous flower heads. Following pollination, these are the source of the so-called coffee cherries. These are drupes, and the two seeds inside are what we know as coffee beans.
Coffee originated in tropical Africa and Madagascar, but is now found in all tropical and subtropical regions.
Blending creates flavour profiles
Arabica, robusta and many provenances
Not all coffee is the same. As well as the species, arabica or robusta, the growing area – known as the provenance – has a major influence on the aroma and appearance of a coffee.
Almost all coffee roasters blend their coffees, not only for financial and taste reasons, but also to even out natural fluctuations in quality and to create the required flavour profile. Beans of widely different provenances can be included in a single blend in order to achieve the desired character.
The two most important coffee types, arabica and robusta, differ in terms of flavour, appearance and price. Accordingly, they also have different areas of application. Thus, robusta should not be left out of certain coffees – such as espresso – as the beans have a low acid content.
With a 61% share of coffee production, arabica is the best-known coffee plant. Arabica only grows at altitude, up to the vegetation border. For this reason, the plant is often described as ‘highland coffee’.
An often elegant, fine and complex aroma can develop in the highlands of South and Central America, as well as in East Africa.
Tropical regions are ideal for the growth of arabica plants, as they offer perfect conditions in terms of precipitation and temperature. This allows the arabica coffee beans to ripen relatively evenly and to be harvested once or twice a year on average.