Evaluation of the thermophysical properties of tylose gel under pressure in the phase change domain

The accurate knowledge of the thermophysical properties of foods under pressure is essential to optimize high-pressure processes in the food industry. In this paper, two generic models are proposed based on the food composition: the additive model under pressure and the ‘shifting approach’. The first one employs thermophysical properties of ice and water under pressure calculated as accurately as possible using sophisticated routines. The shifting approach offers a less accurate, but considerably faster alternative for modeling purposes. This obtains thermophysical properties of foods under pressure shifting data at atmospheric conditions according to the freezing point depression at the prevalent pressure. These models were applied to the case of tylose, a methylcellulose gel that is often used as a model food system. At atmospheric conditions, both models gave similar results for all the studied properties. Under high pressure, the shifting approach undervalued the density and overestimated the specific heat values. However, both methods gave similar results of thermal conductivity, apparent specific heat and enthalpy.