Thin layer drying process of some leafy vegetables under open sun.

摘要

Open sun drying experiments were conducted on thin layers of crain-crain (CC; Corchorus olitorus), fever (FV; Ocimum viride) and bitter (BT; Vernonia anyadalina) leaves grown in Abeokuta, Nigeria. The drying process took place in the falling rate period and no constant rate period was observed from the drying curves. 8 thin layer mathematical drying models were compared using multiple determination coeff. (R2), reduced phi2 and root mean square error (RMSE) between the observed and predicted moisture ratios. The Midilli model satisfactorily described the drying curves of the 3 types of leaves, with: R2 of 0.9980, phi2 of 2.0 x 10-4 and RMSE of 1.09 x 10-2 for CC leaves; R2 of 0.9999, phi2 of 2 x 10-6 and RMSE of 1.11 x 10-3 for FV leaves; and R2 of 0.9998, phi2 of 1.9 x 10-5 and RMSE of 3.3 x 10-3 for BT leaves. The effective diffusivity was found to be 52.91 x 10-10, 48.72 x 10-10 and 43.42 x 10-10 m2/s for CC, BT and FV leaves, respectively.