Drying Characteristics and Kinetics of Bitter leave (Vernonia amygdalina) and Scent leave (Ocimum gratissimum)

Abstract

The effect of temperature on drying of bitter leave and scent leave was studied, using laboratory moisture content analyzer, at temperatures of 50^oC, 60^oC, 70^oC and 80^oC. The falling rate phenomenon was observed for both bitter leave and scent leave. The thin layer drying models were fitted to the experimental moisture ratio data. Among the mathematical models investigated, the Page model described better the drying behavior of bitter leaves and scent leaves with highest R² and lower x² values. The determined effective moisture diffusivity (D_eff) values showed the temperature dependency both materials. Effective moisture diffusivity ranged from 8.437 x 10^-15 to 2.96 x 10^-13 m²/s for bitter leave and 8.65 x 10^-14 to 4.51 x 10^-13 m²/s for scent leave with increase in temperature. Hence, the Arrhenius equation was employed to ascertain activation energy for the different samples dried. Activation energies of 53.55kJ/mol and 110kJ/mol for bitter leave and scent leave were obtained respectively.

Keywords: drying, kinetics, bitter leave, scent leave, effective moisture diffusivity