An inverse method to estimate thermophysical properties of foods at freezing temperatures: apparent volumetric specific heat

摘要

A new approach for the estimation of thermophysical properties of foods at freezing temperatures was explored, analysed and discussed. Semi-empirical formulae were considered for predicting thermophysical properties. Assuming a known function for apparent volumetric specific heat in the freezing temperature range, a simple heat transfer experiment was designed to estimate the unknown parameters. Temperature versus time was recorded at the bottom in the model food undergoing one-dimensional freezing. By solving the partial differential equation with a finite difference scheme coupled with an optimisation technique, parameters were obtained that provide the best least square fit between the experimental and predicted time-temperatures curves. The accuracy of this new methodology was validated using Tylose MH-1000 as a model food. Statistical analysis showed no significant differences between reported and estimated curves. Determined parameters agreed well with values reported in the literature. The determination of thermophysical properties from an inverse method is an attractive technique both from the experimental and methodological point of view.