Optimization and validation procedures: Both numerical and
multiple graphical optimizations were employed to determine the
exact optimum point of different hot-air drying conditions on the
physicochemical properties of dried kaffir lime leaves leading to
desirable response goals. As mentioned by Mirhosseini et al.24,
for graphical optimization procedure, the reduced models were
illustrated as three-dimensional (3D) response surface plot to better
visualize the interaction effect of main drying conditions on the
physicochemical properties of dried kaffir lime leaves. The optimum
drying process performed at 4.9 h, 60°C and 1.4 kg/m2 was proposed
to provide dried kaffir lime leaves with optimum quality.