Deep-fat frying is a widely used and industrially important food process. The fried food develops a crispy porous structure in addition to avour and other chemical changes that is desired by the consumer. During deep-fat frying, the food is immersed into the oil at a high temperature (1802 190°C) that leads to intensive vapourization of the water in the food and transport out through the surface. As water moves out, part of the pore spaces are taken up by the frying oil moving into the material. The oil picked up by the food during the frying process has increasingly
become a public health concern and there is a strong desire to reduce the oil content. A better understanding of the transport processes and their relationship to various parameters should provide ways to optimize the frying process, thus controlling oil pickup, for example. A mathematical description of frying at different levels of complexity has been reported. The simplest description can be empirical curve ts of experimental data1,2. A large number of models have been based on simple diffusion of energy and mass, with various approximations to account
for evaporation and sometimes ignoring evaporation altogether. For example, only the diffusion of energy and moisture was considered without evaporation in the works of Rice and Gamble3 and Dincer and Yildiz4. Dagerskog5 calculated temperatures using only the diffusion term in
the energy equation and did not acount for the latent heat of evaporation. The evaporation interface was tracked by simply knowing the location where temperature exceeded 100°C from the solution to the energy equation. The amount of evaporation was calculated by following the rate of movement of the interface.