Roasted Robusta coffee beans. Those on the left have been roasted at 210°C to 220°C, are of a rich brown colour and have a slightly bittersweet flavour.

The ones on the right have been roasted at a temperature of 220°C to 240°C, have a bold, smoky, bittersweet taste and a dense caramel-like sweetness. The latter is the more popular blend in Thailand. During the roasting process caramelization takes place and the colour of the bean changes from pale green to light or dark brown, depending on the temperature: the higher the temperature, the darker the beans.