Chlorophyll Retention and Drying Characteristics of Ivy Gourd Leaf (Coccinia grandis Voigt) Using Tray and Heat Pump–Assisted Dehumidified Air Drying

Abstract

The maturity of ivy gourd leaves was based on total chlorophyll and chlorophyll a. Desorption isotherms for fresh and blanched ivy gourd leaves have been measured. A nonlinear regression program was applied to the experimental data to fit with any of the four moisture sorption isotherm models. The modified Henderson model gave the best fit. Ivy gourd leaves were pretreated by different blanching methods prior to drying under three temperatures of 50, 55 and 60°C in tray and heat pump–dehumidified dryer. The drying data were fitted to the modified Page model. The drying constant was related to air temperature using an Arrhenius model. Effective moisture diffusivities were determined using the drying data. The degradation of total chlorophyll followed first-order kinetics. Heat pump–dehumidified drying and blanching methods reduced drying times. Quality evaluation showed best quality for ivy gourd leaves pretreated by blanching with chemicals and dried at 50°C in a heat pump–dehumidified dryer.