Two-phase (solid–fluid) coupled transfer phenomena modeling during frying of potato slices: Effect of the product surface-to-volume ratio

Surface-to-volume ratio (SVR) during deep-fat frying affects the rates of momentum, heat, and mass transfer, leading to influencing the final product quality. Mathematical modeling of simultaneous transport phenomena was developed to investigate the influence of the SVR on oil velocity and temperature, as well as product temperature, moisture, and oil distributions, during the frying of potato strips. Considering three different SVRs (3, 3.73, and 5.5 cm⁻¹), the maximum oil velocity ranged from 5 to 27 mm s⁻¹, coinciding with upward trends of the oil temperature. The temperature at both the top and bottom surfaces of the potato strips increased rapidly up to the evaporation temperature. It remained constant for some time due to the onset of the surface evaporation and then increased until the end of the frying. Results also showed that the oil uptake intensified sharply by increasing the SVR during the initial 90 s of the frying, followed by an upward trend until the end of the process but at a lower rate. The developed model could help to assess various product and oil variables during frying to better control the process to produce low-fat fried products.