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The world of coffee is a complex and fascinating one.  To help you get started in a voyage of discovery, here is a brief introduction.

Species, Varieties and Cultivars!

What we know as coffee, in botanical terms, will be one of over 120 species that form the Coffea genus.  The most common of these species in the coffee-drinking world are Coffea arabica and Coffea canephora – which is the species name for Robusta coffee.

Arabica coffee was the first species described botanically, and spread throughout the world for its seeds. Originally grown in Ethiopia (see The Coffee Story) Arabica coffee comprises about 70% of the world’s coffee production. It generally requires higher altitudes (600mts+) and an equatorial climate. The term High-Grown coffee is an indicator of quality, and is therefore difficult to grow and harvest, requiring much manual labour and thus commands high price.

Robusta coffeeis more frequently grown at lower altitudes and on flatter terrain allowing for mechanical harvesting, and can be grown in environments where Arabica cannot survive.  The Robusta bean has a higher caffeine content than Arabica, and is often used a component in coffee blends.  Vietnam is the world’s largest producer of Robusta.

Within each species of coffee, there are a number of varieties, which are described as having a distinct appearance from other varieties, but will hybridize freely with those other varieties. Cultivars are cultivated variants of a species derived through human influence. These could be selected from existing cultivated stock or from wild populations.

In terms of varieties, there are too many to mention them all here! They are chosen for their resilience to rain or insects, and how they respond to the soil and the coffee processes to be used to produce the ‘green’ coffee beans.

Some of the most common variants are

  • Typica – this is a tall cultivar of Arabica brought to Java from Yemen in the early 1700’s.

  • Bourbon – a common cultivar that developed on the Île Bourbon in the Indian Ocean, now known as Réunion.

  • Caturra – a dwarf variety of Bourbon, developed in Brazil.

Coffee Processing

Once the coffee ‘cherries’ have been harvested at the farm, there are three main methods of processing coffee, to produce the ‘green’ beans ready for roasting:

  • Natural / Dry Processed – cherries are picked from coffee plants, and separated in to ripe, over-ripe, under-ripe and damaged cherries.  All other impurities like stones and twigs are then removed. Ripe cherries are next spread out onto stone/brick patios and dried out in the sun for several weeks.  In some regions they are placed on wooden tressels called Indian Raised Beds. Cherries are raked and turned to allow for even drying and prevent mildew, which in turn affects the flavour when the beans are processed. The beans are then sent to the mill for hulling (where the outer pulp is removed from the bean) and grading. The Natural Process is especially prevalent in areas where water is scarce e.g. Ethiopia
  • Wet / Washed Processing – picked cherries are washed in tanks of water and then put through a de-pulping machine where outer part of the cherry is removed. The beans are then left in water for up to 50 hours to remove the sticky mucilage.  Then the beans are dried on patios or Indian Raised beds or sometimes given a helping hand by mechanical driers. The beans are dried to a moisture content of 10 – 12%.
  • Pulp Natural / Honey Processed – the beans are cleaned of impurities and de-pulped (as in the Wet Process) or Dry Pulped i.e. mechanically scrubbed allowing an amount of mucilage to be left on the bean. Where there is a high amount of mucilage left, it is known as Honey Process, or a small amount, it is Pulp Natural.  The beans are then dried on patios or Indian Raised Beds before hulling.