2006 Volume 7 Issue 2 Pages 129-139
Although it is widely accepted as a useful tool for analyzing water migration in food bodies, Fick's law of diffusion is applicable to a single-phase system which is homogeneous in terms of that a flat water content profile is reached at equilibrium when the system is isolated. However, some starchy food often turns into a multiphase system when it is cooked, even though the system is of single phase before it is cooked. In order to make Fick's law of diffusion applicable to such a multiphase system, Relative Water Content Model is proposed in this paper. In this model, relative water content is used as the substitute to water content in Fick's law of diffusion. Relative water content is defined as existing water content divided by the standard water content. The standard water content becomes effective when it is set in such a region of water content where water activity can be approximated as a linear function of water content.
