Background: An analysis of the changes in the quality of edible fats used in the process of frying food products is a crucial issue for both food safety and consumer health. The purpose of this paper is to compare the dynamics of oxidation of selected fats during the frying of French fries at a temperature of 180°C, in an open and closed vessel.
Methods: The subject of the study was the following frying media: rapeseed oil, coconut oil, frying fat and lard, for which characteristic numbers, fatty acid profile and oxidisability were determined. The fats were fried with 20 portions of French fries. The total frying time was 5 hours. In order to determine the oxidative stability of the fats, changes in the Totox index during frying were examined. The results of the research were elaborated by applying kinetic analysis methods. Orders, constant speeds and the speeds of fat oxidation processes were determined.
Results: The dynamics of fat oxidation during frying varied, which was proven by the values of the orders of processes, ranging from 0.2 to 0.7. The rates of oxidation processes were compared on the basis of velocity constants and it was found that rapeseed oil oxidised 1.35 times faster than frying fat, 1.55 times faster than lard and 1.72 times faster than coconut oil. The order of fat oxidisability calculated on the basis of fatty acid profiles was confirmed by the results of the kinetic analysis.
Conclusions: The methods of kinetic analysis applied in this study are well-suited for determining the dynamics of fat oxidation processes during frying. Thus, they can be used as a criterion for selecting an appropriate frying medium.
Keywords: Totox index; frying fats; kinetic analysis; oxidation dynamics.