Efecto del encogimiento y bases de cálculo en la estimación de la difusividad del agua y transferencia de aceite durante el freído por inmersión de alimentos

Abstract

The effect of different modeling assumptions on the estimated water diffusivities and kinetic parameters for oil transfer during deep-fat frying of foods is investigated. Modeling assumptions include the use of several common calculation bases to express water loss and oil absorption, leading to implicit simplifications such as constant density, constant concentration of fat-free solids or constant concentration of non-defatted solids. The proposed model was used to analyze frying experiments conducted with potato strips (9.5 mm×9.5 mm×80 mm) at different temperatures (160, 175 and 190°C), where product shrinkage was followed via image analysis. The proposed model was solved under two-dimensional mass transfer and water diffusivities were estimated by the method of slopes, with and without considering the dimensional changes of product. Mean water diffusivities were calculated in the range of 0.89×10-8 to 4.86×10-8 m2/s for the different calculation bases. The way in which water and oil contents are expressed during frying leads to important changes on estimated diffusivities, comparable to those caused by product shrinkage.