Physical-chemical aspects of the frying process

Abstract

Frying is a very elaborate cooking procedure where the heat is distributed to the food by a medium, the oil or fat that intervenes in the process, interacting with the food itself. The interactions are depending on the quality of the oil or fat, the technology utilized and the nature of the substrate. In effect that last is a mixture of various chemical entities that behave differently toward the heat, between them and with the cooking fat. One of the most important component of the food is water and the hydration conditions are of great importance in determining the various step of the cooking operation and the type of interactions between the food itself and the oily phase. Chemical nature of the substrate is important in determining the type of secondary processes that develop during frying and in effect transformations of the lipidic medium are notably influenced. Main chemical reactions that occur during the frying process are of oxydative nature but their importance must not be overestimated and still frying conditions as well as chemical and physical nature of the food is important in determining the extent at which it occurs. Hydrolysis is another of the reactions that develop during frying. Interchange of fats occurs between the substrate and the lipidic phase, sometime bringing to healthier foods, provided a proper choice in the quality of the frying media has been done. Exchanges of many components, usually minor components occur and are of interest in the repeated frying because they have influence on the behaviour of the cooking operation. In general terms frying must be evaluated as a beneficial operation directed to enhance the nutritional value of a food, provided that the fundamental rules governing the process are observed.