Rehydration Characteristics of Microwave –Dried Thunbergia Laurifolia Leaves
The aims of this work were to investigate the impact of pretreatment and microwave powers on rehydration
properties of microwave-dried Thunbergialaurifolia (T. laurifolia) leaves and to perform modeling studies to explain
rehydration behaviors of the dried leaves. Fresh and blanched T. laurifolia leaves were subjected to dry in microwave dryer
at 450, 720 and 900 W. Rehydration properties including rehydration ratio (RR), weight gain (WG) and co-efficient of
reconstitution (CR) were determined. Rehydration data were fitted to four mathematical models namely, Phoungchandang
model, Peleg model, First order kinetics model, and Exponential model. The results revealed that the rehydration properties
of microwave-dried leaves were in the ranges from 3.58 0.02to 6.97 0.11, 257.59 ± 2.33to 597.29 ± 10.76% and 0.60 ±
0.02to 1.71 ± 0.03 for RR, WG and CR, respectively. The Peleg model was the best model due to the highest values of R2
(>0.9966) and the lowest values of SEE (<0.0124) and RMSE (<0.0120). The k1 and k2 constants of Peleg model were in
the ranges from 3.43 to 10.05 min·gd.b.·g H2O-1 and 1.17 – 1.28 g d.b.·g H2O-1. Blanched T. laurifolia leaves and dried by
microwave dryer at 450W was the best microwave drying condition due to the highest RR (6.97 0.11), WG (597.29 ±
10.76%) and CR (1.71 ± 0.03) and the lowest Peleg rate constant (3.43 min·gd.b.·g H2O-1) among other drying conditions.
Keywords - Mathematical model, Microwave drying, Rehydration properties, Thunbergialaurifolia leaves.