Modeling and control of thawing phenomena in solute-imnreanated frozen foods

摘要

This work was designed to give a better understanding and control of the mechanisms of simultaneous thawing and mass transfer occurring in a material in isothermal contact (T < 0℃) with an aqueous freezant. Two models of heat and mass transport in a porous medium were developed, one solved numerically and the other analytically. Despite different levels of simplification of the phenomena, simulations using both models demonstrated similar mechanisms, including the progress of a sharp thawing front separating a frozen, non-impregnated inner layer from a thawed, highly impregnated outer (surface) layer. The work contributes not only to our understanding of the underlying mechanisms but also develops a very simple tool for predicting thawing/impregnation phenomena during cold immersion storage. The time-course changes in the thawing front and solute gain obtained experimentally with apple pieces and those predicted by the analytical model were in good agreement, with only two food structure variables being identified for this purpose. The effect of process vanables predicted by the analytical model was consistent with trends previously observed with real food, for instance an absence of thawing if the food was stored in a biphasic mixture.