A bag of coffee beans usually names a bean species and a roast level. These two details shape the taste more than almost anything else on the label.
Arabica and robusta
Almost all commercial coffee comes from two species.
- Arabica grows at higher altitudes and is more sensitive to climate and disease. Its flavour is generally sweeter and more aromatic, with notes of fruit, nuts, chocolate or flowers, and its acidity is brighter. It contains less caffeine.
- Robusta is hardier and easier to grow at low altitude. It tastes stronger, more bitter and earthy, often described as rubbery or woody, and it contains roughly twice the caffeine of arabica. It also produces a thicker crema, the foam on espresso.
Many espresso blends combine both to balance sweetness, body and crema. A label reading 100% arabica means no robusta is present; a blend lists the ratio or simply says blend. Neither is automatically better: the choice depends on whether you prefer a smooth cup or a bold one.
Roast levels
Roasting turns green beans brown and develops flavour. A longer or hotter roast gives a darker bean.
- Light roast: pale brown, dry surface. Keeps more of the bean's origin character, with higher acidity and fruity or floral notes. Often used for filter brewing.
- Medium roast: a balance of acidity, sweetness and body, with caramel or nutty tones. A common general-purpose choice.
- Medium-dark and dark roast: darker beans with an oily surface in the darkest cases. Flavour moves toward bitterness, smoke, cocoa and burnt sugar, and acidity falls. Common in traditional espresso blends.
Caffeine content is not changed much by roast level in a meaningful way, so a dark roast is not necessarily stronger in caffeine. It is stronger in flavour.
Reading a bag
- Look for a roast date or a best-before date; roasted beans taste freshest in the weeks after roasting.
- Whole beans keep their aroma longer than ground coffee. Store them in a cool, dark place in a sealed container.
- Check the intended use. Beans labelled for espresso are typically roasted darker; filter beans tend to be lighter.
- For bean-to-cup machines, very oily dark beans can clog some grinders, so read the machine manual.
Strength scales printed on packaging, such as 1 to 5, are set by each producer and cannot be compared between brands.