Arabica vs Robusta

Look at any bag of coffee in a supermarket and there is a decent chance it says “100% Arabica” somewhere on the front, usually in a font that suggests this is important. Almost nobody buying it could tell you what the alternative is.

The alternative is robusta, and between them these two species account for essentially all of the coffee sold in the world — the National Coffee Association puts arabica at approximately 62 percent of world production and robusta at approximately 38 percent. They are genuinely different plants that grow in different places and taste different, and knowing which is which is one of the few pieces of coffee knowledge that pays off immediately when you are standing in front of a shelf.

Side by side

Where they grow, and why that explains the price

Arabica is the fussier plant. The NCA describes it as needing a steady, mild temperature — ideally between 59 and 75 degrees Fahrenheit — around 60 inches of rainfall a year, and it is generally grown between about 2,000 and 6,000 feet above sea level. Those conditions exist in a limited number of places, mostly on mountainsides, and mountainsides are difficult and expensive to farm.

Robusta prefers hotter, more humid conditions — constant temperatures between 75 and 85 degrees Fahrenheit — and grows at far lower altitudes. Lower, flatter land is easier to work and the plant is hardier, which is why robusta is cheaper per pound and why it dominates the parts of the market where price is the main variable: instant coffee, budget supermarket blends, and the filler in cheap ground coffee.

That is the honest explanation of the label. “100% Arabica” is essentially the producer saying “there is no cheap filler in here”. It is a real signal, and it is a much weaker one than people assume — because it says nothing at all about how the coffee was grown, roasted, or how long it has been sitting on a shelf.

What they taste like

The NCA’s own words are the fairest summary. Arabica produces “fine, mild, aromatic coffees”; robusta produces “strong, bold flavors with bitter undertones” and a pronounced aftertaste.

In practice, arabica is where all the flavours people describe when they get enthusiastic about coffee live — citrus, berry, chocolate, caramel, florals. The NCA names Bourbon, Caturra, Geisha, Yirgacheffe and Typica among arabica varieties, and the differences between those are the reason single-origin coffee is interesting at all. Robusta is a blunter instrument: heavier, more bitter, more rubbery in the worst examples, and much more consistent from bag to bag.

Both are transformed by roasting, which matters more to the cup than species does. A light-roasted arabica and a dark-roasted arabica taste less alike than a dark-roasted arabica and a dark-roasted robusta do — see light vs dark roast for what happens in the roaster and why it dominates.

The caffeine difference is the biggest bean-side variable

The NCA puts robusta at about 50 to 60 percent more caffeine than arabica. That is far larger than any difference between roast levels — the NCA notes light roasts carry only a slightly higher amount of caffeine than dark, and that the strong flavour of a dark roast is not associated with caffeine levels at all.

So if you drink instant coffee or a cheap supermarket blend and find it hits harder than the specialty bag you bought at the weekend, that is a plausible reason rather than imagination. It still sits well below the effect of how much coffee you use per cup, which is the variable that dominates everything — our how much caffeine is in coffee guide sets the FDA’s published ranges alongside it.

When robusta is a feature, not a compromise

It is worth defending robusta briefly, because the specialty world’s contempt for it is not the whole story. In espresso, robusta contributes body and a thick, persistent crema, and that is part of what people recognise as traditional Italian espresso. A number of classic Italian blends include it on purpose.

This matters if you are buying espresso beans for somebody who likes the taste of Italian bar espresso. A 100 percent arabica specialty espresso is a different and often more delicate drink; it is not automatically what they want. Our best coffee beans for espresso covers both directions, and Lavazza vs Illy compares the two supermarket giants that sit at the heart of that style.

Does it matter when you're buying a gift?

Mildly, and less than three other things. If you are choosing a bag for somebody else, in order of importance:

• Whole bean or ground, matched to whether they own a grinder. This is the one that can make a gift unusable — see whole bean vs ground.
• Roast level, matched to how they drink it. A dark roast is the safe gift for most people; a light roast is a gift for somebody whose taste you actually know.
• Freshness, meaning a bag with a roast date on it rather than only a best-before.
• Species, which for practically every bag you would consider giving is arabica anyway.

Put differently: if the bag says 100% arabica, that is a small point in its favour and no guarantee of anything. If it does not say, and it is a cheap supermarket blend, expect a heavier and more bitter cup with more caffeine in it — which for some people is exactly the coffee they want.