After computing the moisture ratio using the thin
layer (10 mm thick) drying data, the STATGRAPHICS
(Version 7.0 for DOS, Manguistics Inc, Cambridge,
MA) statistical software package for non-linear regression
analysis was used to fit moisture ratio against drying
time and determine constants of Eqs. (1)–(4) for the
four selected drying models. The regression constants,
and coefficient of determination (R2) for these four
models are given in Table 1. From the table, it is obvious
that the Page models have higher R2 and therefore
represents the drying characteristics of kale (for individual
drying runs) better than either the Newton or the
Henderson and Pabis model. Also, the drying rate constants
presented in Table 1 fall within the range of those
complied by