Experimental data and modelling of thermal properties of ice creams

In order to model the heat transfer phenomena which take place during ice cream freezing, predictive correlations of the ice cream thermophysical properties as a function of temperature are needed, principally the specific enthalpy and the thermal conductivity. Due to the fact that these thermal properties are required for various freezing conditions and ice cream formulations, physical models based on large experimental determinations were developed and validated. For a given ice cream formulation, the thermal conductivity was dependent on its density i.e. on the amount of air fraction in the sample and on the temperature whereas the enthalpy is only affected by temperature. The main objective of this study was to develop physical models that predict the thermal properties of a standard overrun ice cream based on its composition and on the intrinsic thermal properties of each major pure component. In addition, to validate these models, the thermal properties of the ice cream were measured experimentally-the enthalpy by DSC and the thermal conductivity by the transient hot-wire probe method-and the effects of different factors were observed: ice content; temperature and air fraction in the temperature range between -40 and 10 degreesC. Generally, the predicted thermophysical properties values were in close agreement with those obtained experimentally. (C) 2003 Elsevier Science Ltd. All rights reserved.