What is a roast recipe in coffee roasting?

A roast recipe is a set of programmed instructions that a roasting machine follows to automatically adjust settings - power, fan speed, drum speed - at specific times or temperatures during the roast. It's distinct from a roast profile (which is a record of what happened during a roast) in that it's a forward-looking instruction set rather than a backwards-looking log.

On machines that support them - including the Aillio Bullet via RoasTime software - roast recipes allow semi-automatic roasting: the machine makes pre-programmed adjustments at defined points while the roaster monitors and can override if needed. A recipe might specify: at yellowing, reduce power from P8 to P6; at first crack minus 30 seconds, reduce fan to F3; one minute into development, drop. The machine executes these steps automatically.

For home roasters, roast recipes offer a useful middle ground between fully manual roasting (where every adjustment is made by hand in real time) and fully automatic roasting (where the machine runs a fixed programme without human input). They reduce the cognitive load of managing multiple variables simultaneously while still allowing the roaster to intervene when a batch is running differently to expected.