Method for roasting coffee beans

A method of roasting coffee beans in a vessel, the method comprising:

• applying, by an electrical heater controlled by a control system, a roasting recipe dedicated to roasting partially pre-roasted beans, wherein the roasting recipe comprises a temperature versus time profile, wherein applying the roasting recipe comprises controlling the electrical heater to apply the temperature versus time profile inside the vessel based on a measure of at least one temperature sensor positioned in the vessel, wherein a temperature measured inside the vessel is used to adapt a power of the electrical heater in a feedback loop,
• measuring a concentration of at least one volatile organic component in smoke produced in the vessel during the applying of the roasting recipe,
• detecting an increase of the concentration in function of time,
• stopping, by the control system, heating when a first part of the increase of the concentration is detected before a set reference time to, wherein the set reference time to is 3 minutes, and
• stopping, by the control system, heating when no increase of the concentration is detected after a set reference time t1, wherein the set reference time t1 is 5 minutes.