Effects of Drying Temperature on The Effective Coefficient of Moisture Diffusivity and Activation Energy in Ibadan-Local Tomato Variety (lycopersicum esculentum)

Abstract

A study of the mechanism of mass transfer phenomena of Ibadan-local variety was carried out. Ibadan-Local tomato varieties pre-treated in a binary (sugar and salt) osmotic solution of concentration (45/15^oBrix), solution temperature (30, 40, 50^oC), was studied by developing a mathematical model to describe the Water Loss (WL) and Solid Gains (SG). Drying was monitored at three temperatures (40, 45 and 50^oC) until   equilibrium weight was achieved using the oven-dry method. Five thin layer drying models (Exponential, Henderson & Pabis, Page, Modified Page and Logarithmic) were compared and fitted into the experimental values of the non-linear moisture ratio; MR. The diffusion coefficient and activation energy were determined using the Arrhenius equation. Drying occurred in the falling rate phase and different models fit at different temperatures. Calculated values of effective moisture diffusivity varied from 1.17-3.51x10^-8 to 1.25-3.13x10^-8 and activation energy varied from a maximum of 52.61KJ/mol in treated to 46.81 KJ/mol in untreated tomato. At all temperatures, effective coefficient of moisture diffusivity and activation energy values was higher in osmosized tomato

Keywords: Osmotic dehydration, Water loss, Solid gain, Effective moisture diffusivity and Activation energy.