The degree of roast of coffee beans during conventional, combined conventional-vacuum, or vacuum roasting processes was evaluated by means of the weight loss determination (Table 1). As expected, in all cases, in the early stages of roasting coffee weight loss proceeded faster than in the later stages and was mainly due to water evaporation. At the beginning of the treatment, for a constant F value, weight losses during the vacuum roasting process were significantly higher than those occurred during the conventional and combined conventional-vacuum roasting. This can be attributable to a lower resistance of water to escape, generated by the very low pressure inside the oven.