Thermophysical properties and thermal behavior of leafy vegetables packaged in clamshells

► Determination of thermophysical properties of leafy vegetables. ► Modeling heat transfer in clamshell of leafy vegetables. ► Simulation of leafy vegetable temperatures in broken cold chain. Little is known about the thermophysical properties of fresh-cut lettuce other than heat of respiration. Empirical correlations based on food composition remain the only way to estimate the thermophysical properties of fresh-cut lettuce. The objectives of this study were (i) to determine the thermophysical properties of several baby-leaf lettuce and brassica greens and (ii) to verify the measured thermophysical properties by using them in a heat transfer model and comparing the predicted product temperatures with measured product temperatures in a simulated interruption of a cold chain. Density, leaf thickness, thermal conductivity, specific heat and water activity from nine varieties of baby-leaf lettuce and brassica greens were measured. A broken cold chain was simulated in a low temperature incubator set at 10°C for a length of time before readjustment at 2°C. Results showed that density (1078–1112kgm−3), leaf thickness (0.18–0.54mm), thermal conductivity (0.55–0.70W (m°C)−1) and specific heat (3.1–4.3kJ (kg°C)−1) varied significantly (P