When talking about coffee, people are usually referring to the fruit from one particular species of tree: Coffea arabica. Arabica makes up most of the coffee produced each year, and it is grown in dozens of countries between the Tropic of Capricorn and the Tropic of Cancer. It isn’t the only species of coffee, however. In fact, over 120 different species have been identified to date but only one other is grown in any quantity and this is Coffea canephora, a plant we commonly refer to as Robusta.
Robusta is actually something of a brand name given to the species, chosen to highlight its attributes. It was discovered in the Belgian Congo (what is now the Democratic Republic of the Congo) in the late-19th century and its commercial potential was clear. It was able to grow and fruit at lower altitudes than the existing Arabica plants, in higher temperatures, and was more resistant to disease. These attributes are what still drive much of the production of Robusta today, and because of the way it is grown it is substantially cheaper to produce. There is an inevitable downside, however: it doesn’t taste very good.
Some people will make a rather specious argument that a really well-produced Robusta coffee can taste better than a poor Arabica coffee and this may be true, but it does nothing to convince us that Robusta actually tastes good. It is generally difficult to ascribe particular tastes to coffees, but I think it would be fair to say that Robusta has a woody, burnt-rubber quality in the cup. It usually has very little acidity, but will have a heavy body and mouthfeel. There are, of course, grades of quality within Robusta, and it is possible to produce higher-quality Robustas. It has been a staple of the Italian espresso culture for many years, but currently most of the Robusta produced around the world ends up in large manufacturing plants destined to become the pariah of our industry: instant soluble coffee.
For the soluble coffee industry, price is far more important than flavour, and the global reliance on coffee as a fast-food product means that Robusta makes up around 40 per cent of the world’s coffee produced each year. This percentage is somewhat variable, driven by fluctuations in price and demand. For example, an increase in the global price of coffee may result in more Robusta production, as large multinational coffee companies may need to find cheaper alternatives to Arabica. Interestingly, in the past when roasters have substituted Robusta coffees for Arabica in big commercial blends, there has been a downward trend in coffee consumption. This might be related to flavour, or to the fact that Robusta has about twice the caffeine content of Arabica. Either way, when big brands cut corners, consumers notice – or at least change their coffee-drinking habits.
THE GENETICS OF COFFEE
The coffee industry treated Robusta like an ugly sister to Arabica until a rather interesting genetic discovery was made. Once scientists began sequencing the genes, it became clear that the two species are not cousins or siblings. Instead it appears that Robusta is, in fact, a parent of Arabica. Most likely somewhere in southern Sudan, Robusta crossed with another species called Coffea euginoides and produced Arabica. This new species spread and really began to flourish in Ethiopia, long considered the birthplace of coffee.
Taken from a 19th-century book of medical botany, this handcoloured copperplate engraving by James Sowerby illustrates the white flower, bean and leaf of Coffea arabica.
Currently 129 species of Coffea have been identified, mostly through the work of Kew Gardens in London, though most look very different to the plants and beans we are familiar with. Many of these species are indigenous to Madagascar, though others grow in parts of southern Asia, even as far south as Australia. None of these species has any commercial attention at the moment, but scientists are beginning to show more interest in them because of a concern facing the coffee industry: the lack of genetic diversity of the plants currently in cultivation.
The way that coffee has spread around the world means we have a global crop with a common ancestry. There is little variation in the genetic make-up of coffee plants, and this exposes global coffee production to massive risk. A disease that can attack one plant can likely attack them all, something the wine industry suffered with Phylloxera, an aphid that devastated huge swathes of grape vines across Europe in the 1860s and 1870s.
Most of the 129 species of Coffea are indigenous to Madagascar but plantations around the world, such as this one in Queensland, Australia, mean that it is now a global crop.