Thermo‐physical Properties of Selected Vegetables as Influenced by Temperature and Moisture Content

Thermo‐physical properties of selected vegetables (cassava, eggplant, ginger, green pepper, white radish and zucchini) were evaluated under different conditions of temperature (5 to 40C) and moisture content (30 to 94% wb). Test samples were equilibrated to a given temperature and moisture content prior to use. The thermal conductivity and heat capacity were measured using the line heat source probe and the differential scanning calorimeter, respectively. Depending on the state, temperature, moisture content and the type of vegetable, average heat capacity varied from 1.5 to 4 kJ/kgC, while the thermal conductivity varied from 0.08 to 0.60 W/mC. Heat capacity of the unfrozen vegetables was found to be approximately twice as much as values obtained for the frozen ones. Although both temperature and moisture affected the thermal conductivity, the latter had the greater influence. Generally, differences in measured data and responses to both temperature and moisture content were attributed to differences in structural characteristics and composition. Correlations were developed for estimating thermo‐physical properties of several vegetables.