2005 Volume 33 Issue 2 Pages 93-100
The thermal conduction induced close to the heating plane was detected along the one-dimensional axis (x axis) in foodstuffs such as food models, cereal flour doughs, and highly moisturized foods during pan broiling (heating in a metal vessel) at 105 °C , frying at 180 °C , boiling at 100 °C , steaming at 100 °C , and baking at 170 °C , using the newly provided heating devices. The velocity of increasing temperature monitored in each sample was ranked highest to lowest in the order of frying, boiling, steaming, pan broiling and baking, irrespective of temperature in each heat transfer medium. The increasing temperature vs. heating time curve for all the samples was in conformity to an exponential equation derived from an assumption that a retardation phenomenon plays a role in the thermal conduction. A power relationship was also found in double-logarithmic plots of reciprocal of the retardation time in the exponential equation vs. effective thermal diffusivity α (= λ / Cp ·ρ, where λ is the thermal conductivity, Cp is the heat capacity at constant pressure, ρ is the density) for all the samples. The power coefficient in this relationship describes a distinctive feature of the heating procedures in cooking.
