Effective thermal diffusivity of food gels impregnated with air bubbles

A predictive model of the effective thermal diffusivity of food gels impreg nated with air bubbles was proposed. The model included the effect of laten t heat transport accompanied by water vapor diffusion within the bubbles in addition to heat conduction. To discuss the reliability of the model, the effective thermal diffusivities of several air-impregnated gels were measur ed and compared with the predicted values. For air-impregnated gels of low water content, the effective thermal diffusivities measured at 20 degrees C were in good agreement with the predicted values. For air-impregnated gels of high water content, the effective thermal diffusivities were well appro ximated by the predicted values up to 50 degrees C. At higher temperatures, the model tended to overestimate the effective thermal diffusivity especia lly for the gels of high porosity. (C) 1999 Elsevier Science Ltd. All right s reserved.