Mathematical modeling of drying characteristics of Jew’s mallow (Corchorus olitorius) leaves

Abstract

Drying behaviour of Jew’s mallow leaves using an oven dryer was studied. The influence of drying temperatures (50, 60 and 70 °C) on moisture content of the leaves at stable air velocity was considered. Five drying models, including, simple exponential, Page, Two-term exponential, Logarithmic, and Wang and Singh were fitted to drying data. Two-term exponential model adequately express the drying behaviour of Jew’s mallow leaves. Effective moisture diffusivity of Jew’s mallow leaves ranged from 8.18 × 10−8 to 1.13 × 10−7 m2/s. Dependence of the computed effective diffusivity on oven temperature was obvious. The energy required for oven drying of Jew’s mallow leaves was found to be 14.84 kJ/mol. The L∗, a∗, b∗, ΔE, a∗/b∗ colour characteristics of the dried leaves range from 31.8 to 32.87, −3.73 to −4.37, 13.6 to 16.47, 69.00 to 69.73, and −0.26 to −0.34 respectively. Oven drying conditions of 50 °C 150 min and 70 °C 90 min resulted to dried leaves with desirable colour characteristics. Keywords: Jew’s mallow, Oven drying, Mathematical modeling, Colour, Effective diffusivity, Activation energy