The Effect of Industrial Roasting on the Physicochemical and Sensory Characteristics of Arabica and Robusta Coffee Beans

The effect of three types of industrial roasting (light, medium, and dark) on the characteristics of two varieties of imported green coffee, Coffea arabica (Arabica) and C. canephora (Robusta) was investigated. The moisture content and water activity of samples decreased significantly during roasting. In dark roasting, the moisture contents of Robusta and Arabica beans were 0.39 and 0.41%, respectively. The caffeine and chlorogenic acid levels in green and roasted Robusta coffee were higher than Arabica coffee. The caffeine increased during roasting and reached 149.7 and 61.8 mg/l in dark roasted Robusta and Arabica, respectively. Chlorogenic acid decreased during roasting and in dark roasting, a very small amount (0-0.21 mg/l) remained in the studied samples. Roasting made the coffee beans crispier. The hardness of green beans decreased from 33.4-34.0 to 14.0-14.8 N in dark roasted samples. The color properties of coffee beans mainly changed from green to brown. Roasting reduced the antioxidant activity of the coffee and it decreased further with increasing temperature and time. The antioxidant potential of dark roasted samples reached 30.1-38.1 % of free radical inhibition at the highest concentration. Roasting produced a significant improvement in the sensory characteristics of the coffee drink. The drink made from Arabica coffee had a better appearance, aroma and taste. The coffee drink made from light roasted Arabica beans had a higher overall acceptance. Mixing two types of Robusta and Arabica coffee and roasting light and medium can be a good suggestion to prepare a coffee with desirable chemical and sensory properties.