Coffee beans, seeds from the berries of the coffea plant, are one of the world’s most traded commodities. There are over 100 individual species of coffee plant but just two of these, coffea arabica (arabica) and coffea caneaphora (robusta), make up the vast majority, if not all of the commercial grade coffee that’s produced around the globe.
So does it matter which type of bean we buy? Do we even have a choice? What sort of things should I consider before making a decision to buy one bean over the other? How do the arabica and robusta beans compare with each other from a taste perspective?
Let’s start with some generalisations. If arabica and robusta were siblings in the coffea family, arabica would be the eldest, the best looking and the sibling that had all the friends and social connections. Robusta would be short, stout and a bit rough around the edges.
Arabica would wear a well cut suit and dine at expensive restaurants. Robusta probably doesn’t own a suit and would be more than happy with a burger or takeaway fish and chips at the park.
Arabica is a well breed mare with a good pedigree and clean hay in the stables. Robusta is a quarter horse from the top paddock that gives kids rides at the local market each Saturday.
Which raises the question, why is robusta used for making coffee at all?
Well, it’s an easier plant to grow than arabica, much tougher, and has a higher crop yield, meaning that, all other things being equal, robusta is a more commercially attractive crop to grow. Of course all other things are rarely equal, but clearly robusta can be successfully grown in conditions where arabica would struggle. Below 600 metres altitude for example.
Part of the reason that robusta is so hardy is the relatively high concentration of caffeine in the beans (as much as three times the amount of caffeine found in arabica beans). This acts as a natural insecticide to keep insects and disease away from the plant.
Paradoxically, while the high levels of caffeine in robusta make it a resilient plant to grow, it also means an increase in the bitterness of the final coffee brew and the consequent impact on the flavour profile, balance and so on.
Put simply, robusta doesn’t generally taste as good as arabica. In fact it can sometimes taste a little ordinary. A bit tarry. Even rubbery. I say ‘generally’ because some robusta blends are very good and on a par with some arabica blends.
So it’s no surprise that arabica dominates the world coffee scene with its fine flavours and balance. The fact that it outsells robusta globally by 3:1 (roughly 75% of the worlds coffee is arabica and the remaining 25% robusta) says a lot.
Arabica has significantly more lipids (oils and waxes) and sugars than robusta – in the order of 50% more in both cases. When put through the roasting process these compounds produce distinctive aromatics as well as compounds that build body and complexity in the coffee. This may in fact be the keystone difference between arabica and robusta.
Physically the arabica beans are a stretched oval shape while the robusta are more rounded. Arabica bushes can grow to 4 metres or so in height while robusta can grow to over 6 metres high. And if you’re travelling, Brazil is the world’s biggest arabica grower and Vietnam is the world’s biggest robusta grower.
Chlorogenic acid (CGA) is known to have antioxidant and anti-inflammatory properties and is also thought to have a positive impact on blood sugar levels amoung other things. The good news is that raw robusta beans contain up to 10% CGA and arabica have up to 8% CGA. The bad news is that much of the CGA is lost in the roasting process, making this point somewhat invalid, but we thought you should know anyway.
In summary, next time you’re at your local coffee store take home some robusta as well as your favourite arabica and do some comparisons. Ahh, the joys of discovery.