Mathematical modeling of drying kinetics of <i>Verbascum Sinaiticum</i> leaf in a fluidized bed dryer: comparative studies with blanched and unblanched pretreatment condition

Abstract

Verbascum sinaiticum (V.sinaiticum), a plant native to Ethiopia known for its traditional medicinal uses, was dried conventionally at 50, 60, and 70 o C in a fluidized bed dryer with a constant air velocity of 1.5 m/s.Nonlinear regression analysis was used to apply five thin-layer drying models.The results showed that, for both blanched and unblanched, the Page model performed the best, with R 2 =0.9999,RMSE =0.0036, and SSE = 0.0001.The Page model adequately characterized thin layer drying, calculating effective moisture diffusivities using Fick's second law.The results revealed a declining rate period for all temperatures.The range of effective moisture diffusivity was (2.1355.895)10 10 m 2 /s, while the activation energies for moisture diffusion were 43.6 and 41.6 kJ/mol.Blanching drastically lowered the moisture content, which had an effect on color and useful qualities at all temperature ranges.This study offers valuable insights into the optimal drying parameters and blanching methods necessary for preserving the functional characteristics and maximizing the therapeutic potential of V. sinaiticum.