Heat transfer characteristics of cucumbers during blanching Original Research Article

The possible use of blanching in combination with controlled fermentation is being considered as a means to reduce the salt levels needed in the storage of brined cucumbers. To be commercially feasible, the use of heat should be optimized for economic and product quality considerations. This study reports basic information on the heat transfer characteristics of cucumbers needed to optimize the blanching process. Two-dimensional (cylindrical coordinates) heat diffusion equations were used to simulate the heat transfer characteristics of cucumbers during rapid water heating (blanching). The equations were solved by explicit form of the finite difference method. Thermo-physical properties (thermal conductivity, specific heat and density) of cucumbers needed to solve the heat transfer equation were also measured. Temperature (20–95°C) did not significantly affect the thermal conductivity (0.62 W/m K) or specific heat (4.03 kJ/kg K) of cucumber. The maximum standard error of simulated temperatures of the cucumbers from experimental data was 4.5°C. There was no significant change in the moisture level of the cucumber during blanching. Simulation results showed that heat transfer coefficients between 500 and 6000 W/m2 K had no significant effect on the surface and center temperatures of cucumbers during blanching.