Understanding roast levels

Roasting turns a green, grassy seed into the coffee we know. How far it goes shapes almost everything you taste, so the roast level is one of the most useful things to record.

What roasting does

As beans heat up they lose water, turn from green to yellow to brown, and crack audibly as gases escape. Sugars caramelise and hundreds of aroma compounds form. A short roast keeps more of the bean's own character; a longer roast swaps it for the flavours of the roast itself.

There is no official scale, and one roaster's medium can be another's light. Go by what the bag says, and by what you taste.

Light

Light roasts are pale brown and dry, with no oil on the surface. They tend to be bright and fruity or floral, with high acidity and a lighter body. They show off origin best, which is why many speciality roasters favour them for filter coffee. They can taste sour if under-extracted, so a slightly finer grind or hotter water often helps.

Medium

Medium roasts balance the bean's own flavours with sweetness from the roast: think caramel, nuts and milk chocolate alongside softer fruit. Acidity and body both sit around the middle. A good all-rounder for espresso and filter alike.

Medium-dark

Medium-dark beans are richer in colour and may show a few spots of oil. Expect dark chocolate, toffee and a gentle bitterness, with lower acidity and a fuller body. They stand up well to milk, which makes them a common choice for flat whites and lattes.

Dark

Dark roasts are deep brown to nearly black and often oily. Roast flavours lead: smoky, bittersweet, sometimes ashy. Acidity is low and the body heavy. Brew a little cooler and a little coarser than usual to keep bitterness in check.

Recording the roast in Caffèdex

Choose Light, Medium, Medium-dark or Dark in the roast field, using the roaster's description where there is one. Then move the acidity and body sliders to where the cup actually sits. Over time you will see which roast levels you rate highest, and for which brew methods.

• Light: high acidity, light body
• Medium: balanced acidity and body
• Medium-dark: lower acidity, fuller body
• Dark: low acidity, heavy body