Fig. 1 shows the temperature changes of coffee beans during conventional, combined conventional-vacuum and vacuum roasting. The temperature monitored during the vacuum treatment was lower than that recorded during the other two processes, especially in the initial stages of roasting. This can be explained by the higher rate of water vaporisation when compared with the process carried out at atmospheric pressure, due to the very low pressure generated inside the oven. As a consequence, different thermal effects (F) were obtained at the same length of roasting among the considered processes (Table 1).