Changes of quality parameters upon heating were evaluated at different times of microwave heating on refined sesame and soybean oil high and compared to the results obtained for standard chemical indices (free fatty acids, peroxide, p-anisidine, nonenal content). Soybean oil was more extensively oxidised by microwave heating than the other oil probably as a consequence of absence of natural antioxidants.

Trans fats naturally exist in small amounts in the fat in meat and milk, but most trans fats in the food supply have been added by food manufacturers. Since 1911, when Procter and Gamble introduced Crisco, companies have used artificial trans fats because of their commercially favorable properties, such as long shelf life, stability during deep frying, and palatability. These fats have therefore been incorporated into a great many foods, including snack and deep-fried foods, baked goods, margarines, and crackers.