Thermal drying of pepper berries

This paper focuses on the drying kinetics at different temperatures of air in the chamber (lab scale dryer). A theoretical drying model was suggested. A number of experiments were carried out to study the drying characteristics of the fresh pepper berries in a lab scale dryer at six different temperatures which ranged from 30o C to 55o C at 5oC interval. In accordance with the experiments and the proposed model of drying of pepper fruits, the main parameters that contribute to accelerate the process can be distinguished. The parameters include the temperature of drying, the air humidity of the fruits surrounding and velocity of saturated water vapour transfer between the fruits and the surrounding. From the experiments, it was noticed that the change in size over time depends on the drying temperature. The drying process was accompanied by a number of processes that may be taken into account in refining the theoretical model. Characteristic drying time, according to the developed model exponentially depends on temperature, is proportional to the volume of pepper fruit, and inversely proportional to the coefficient of mass transfer. Mass transfer coefficient can be changed by changing of the air flow surrounding the berries in the drying chamber. This will work effectively in case when the drying is limited by high humidity in the surrounding