Frying in a pan is done with the help of hot fat. Again, high temperatures and longer heating times are necessary. In addition to the loss of heat-labile vitamins, the oxidation of unsaturated fatty acids is important, provided that the frying fat used has a high content of these fatty acids, such as olive, sunflower and safflower oil. This occurs when the fat (vegetable oils with a high content of polyunsaturated fatty acid, e.g. linoleic acid) is kept at a high temperature – from 130 °C – for a long period of time. As a result, the fat begins to steam or smoke, respectively, and the fatty acids can easily react with atmospheric oxygen. They transform into toxic compounds – trans fatty acids (trans fatty acids are fatty acids with trans-configured carbon double bonds) – and thus lose their essential effect. Such newly formed compounds have a damaging effect on the body. According to scientific findings, the consumption of trans fatty acids increases the level of LDL cholesterol (in the blood). These are, for example, contributors to atherosclerosis (arteriosclerosis), coronary heart disease (CHD) and myocardial infarction (heart attack). In addition, the body reacts to a deficiency of essential fatty acids – besides unsaturated fatty acids also linoleic acid and linolenic acid – for example with a higher susceptibility to infections, a disturbed heart rhythm as well as disturbed vision, with alopecia (hair loss) and fertility disorders (disturbances of fertility) in men and women. Chemical changes due to long and strong exposure to heat lead to the formation of free radicals. These are equally harmful to the organism, as they accumulate in high numbers in food and thus in the body, degrading essential nutrients and vital substances (macro- and micronutrients). Vitamins in particular are subject to degradation. Furthermore, they attack the body’s cells and are associated with atherosclerosis (hardening of the arteries), rheumatic diseases, disorders of the immune system and immune defense, aging processes and cancer. If too few free radical scavenging antioxidant vitamins A, C, E and trace elements such as selenium, zinc, manganese, copper and iron are present in the body, only an insufficient number of endogenous antioxidant enzymes can be produced, which additionally render free radicals functionless. For this reason, free radicals cannot be rendered harmless, allowing them to damage our cells unhindered.
Especially in beef, the roasting process affects vitamins B1, B6 and pantothenic acid, which can be destroyed by up to 60%. The minerals potassium and magnesium – contained in pork – suffer losses of 25 to 30 % due to the high heating temperatures.
Despite the use of high cooking temperatures, roasting in the oven, in contrast to the use of the pan, is more gentle to health, since no additional fat is used, which could be transformed into harmful compounds. If pieces of meat are on a grill rack, meat liquid and fat can drip off and collect in a pan below. However, the nutrients and vital substances contained in the liquid and fat are transferred to the pan along with it, causing the meat to lose a high percentage of its B vitamins, niacin and pantothenic acid, as well as fatty acids important to the body. The elevated temperatures generate high heat in the fat-soluble vitamins A, D, and E of meat and fish, which the sensitive vitamins cannot withstand. Their reduction or destruction cannot be avoided.
