Heat transfer characteristics of cucumbers during blanching

The possible use of blanching in combination with controlled fermentation i s being considered as a means to reduce the salt levels needed in the stora ge of brined cucumbers. To be commercially feasible, the use of heat should be optimized for economic and product quality considerations. This study r eports basic information on the heat transfer characteristics of cucumbers needed to optimize the blanching process. Two-dimensional (cylindrical coordinates) heat diffusion equations were use d to simulate the heat transfer characteristics of cucumbers during rapid w ater 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 degreesC) did not signific antly affect the thermal conductivity (0.62 W/m K) or specific heat (4.03 k J/kg K) of cucumber. The maximum standard error of simulated temperatures o f the cucumbers from experimental data was 4.5 degreesC. There was no signi ficant change in the moisture level of the cucumber during blanching. Simul ation results showed that heat transfer coefficients between 500 and 6000 W /m(2) K had no significant effect on the surface and center temperatures of cucumbers during blanching.