Coffee Bean Production - Arabica versus Robusta
Arabica or Robusta, what is the difference?
Coffee takes most of the year to grow, 9-11 months. When we say coffee, we mean the coffee fruit. Coffee as we know it comes from the seed inside the fruit and there are 2 seeds per fruit (commonly called beans!). Despite the long growing period, there is coffee being harvested somewhere in the world every season due to the variations in seasons and climate around the world. The berries have to be ripe before they are picked to eventually end up as coffee.
There are 2 main varieties of coffee – Arabica and Robusta. Arabica is known to be the variety associated with speciality coffee due to the complex flavours it can nurture. An arabica coffee bush can produce 1-5kg of coffee fruits in a season with 5kg needed to produce 1kg of coffee beans to make coffee. The taste profile of Arabica and Robusta beans are created by the chemical and biological differences in the plants which means they flourish in different growing environments.
Arabica flourishes between 900 and 2000m above sea level in a temperate climate (15-25 C) with rainfall of 1500-200mm a year. In contrast robusta can grow between 0 and 900m above sea level, likes higher temperatures of 20-30 C and higher rainfall (2000-300mm a year). These different climates and growing conditions create different levels of chemicals in the plant. Arabica beans are 15-17% oil with fewer coffee oils found in Robusta (10-12%). This greatly affects flavour.
Sugar content in coffee – there are natural sugars found in cofee before it is roasted. Very little will survive roasting but the sugar content greatly affects the structure of the coffee bean and the flavour profile. There is up to 9% sugar compounds in Arabica prior to roasting compared to 3-7% in Robusta. Robusta is naturally not as sweet as arabica which gives rise to robusta having a strong, bitter flavour and a strong aftertaste. There is also a large difference in caffeine content between the 2 coffee varieties. Robusta is generally high in caffeine (up to 4%), whereas arabica has a caffeine content of between 0.8% and 1.4%. Caffeine as well as being a stimulant affects flavour as it is a very bitter chemical.
All of these factors explain why arabica tends to be a higher quality coffee bean with regards flavour. The plants grow in a more challenging environment, containing high oil and sugar compounds which gives rise to a spectre of flavours. The chemical composition also greatly affects price. Arabica is naturally more expensive to produce as it only grows in tougher environments to cultivate.