Abstract:
Studying the effects of heating, reheating and exposure to microwave radiation on the structure of five types of edible oils such as olive oil, corn oil, cotton seeds oil, supply oil and sunflower oils in which used two kilograms for each sample and were collected from the origin of production in the local market and considered as fresh oils. Studying the change in the structure of edible oils by nuclear magnetic resonance (NMR) spectra, describe ,in general, a number of regions which can be considered as a base line of comparison to differentiate the properties of fresh oils from that exposed to normal heating or exposure to microwave once or several times. The NMR results revealed changes in the chemical structures of the considered edible oils. The changes occurred in the function groups of the oils especially; the alylic region of the oil (between 1.93 – 2.13 ppm), the bis-alylic region (2.72 – 2.84 ppm), olefeinic region ( 5.2 – 5.4 ppm), hydroproxide region ( 5.9 – 7.2 ppm), and the aldehyde region ( 9.5 – 9.7 ppm). The changes in these regions, indicate degradation and the formation of new complex chemical structures as a result of normal heating. Negligible changes in the chemical structures of the considered oils occurred by microwave heating, this give an impression that microwave heating even with more exposure frequency does not induce any hazards i.e., the absence of aldehyde groups.