Thin Layer Drying Kinetics and Modelling of Spinacia oleracea Leaves

摘要

In the present work, spinach samples were dried using three different drying techniques namely sun, conventional and microwave. Drying experiments were conducted using a constant air velocity and temperature but varying microwave output power. Drying rate enhanced in case of microwave compared to artificial and natural air with lower drying time. The experimental drying data of spinach were applied to seven moisture ratio models, given in literature. Nonlinear regression analysis was performed to relate the parameters of the models with the drying conditions. The performances of these models were evaluated by comparing the coefficient of determination (R~2), standard error and residual sum of squares values. Among all the models, the Parabolic, Page and Midilli models were found to be the best for explaining the drying characteristics of spinach leaves with respect to sun, conventional and microwave treatment. The effective moisture diffusivity was in the range of 10~(-9)- 10~(-10)m~2/sec in all the treatments studied.