Convective Air Drying Characteristics for Thin Layer Carrots

This paper presents a kinetic study of convective drying without pre-treatment of carrot. The effects of the temperature of the drying agent, the speed of the drying agent and the thickness of the kinetics of drying the sample of carrots were investigated. The experiments were carried out with the aid of an installation for drying food products, that is capable of ensuring the temperature of the drying agent (air) in the range of + 25... + 125 degrees C. The drying process was conducted at temperature of 45 degrees C in first hour of process, 2 hours at 55 degrees C, and 3 hours at 60 degrees C. The air velocity was setup at 1.0 - 2.5 m/s. Carrots were divided into segments of a thickness of 0.4 cm. Two mathematical models available in the literature were fitted to the experimental data. The drying rate increases with temperature and decreases with the sample diameter. The Page model is given better prediction than the Henderson and Pabis model and satisfactorily described drying characteristics of carrot slices. In conclusion, the effective diffusivity increases as air- flow rate and temperature increases. Page's empirical model showed a good fit curves than the Henderson and Pabis model.