First, the fat contained in edible oil can be easily converted into trans fatty acids under the action of high temperature. The longer the time of high temperature action, the more trans fatty acids are produced. Trans fatty acids are not only easy to cause cardiovascular and cerebrovascular diseases, but also have obvious adverse effects on children's growth and development, male fertility and brain function.
Secondly, vitamins, unsaturated fatty acids, phytochemicals, mineral ions and other nutrients contained in food are seriously lost after high-temperature frying, and a large amount of oil is introduced, which not only loses the original nutritional value of food, but also easily causes problems such as hyperlipidemia, hypercholesterolemia and arteriosclerosis.
Thirdly, the starch and protein contained in food may produce carcinogens such as acrylamide after high-temperature frying, especially the repeatedly used edible oil.
Fourthly, fried food is difficult to digest because of its changes in nature, which easily affects the gastrointestinal function and the functions of other digestive organs such as liver, gallbladder and pancreas.
Fifth, it is difficult for many fried foods to ensure food hygiene and quality, especially roadside stalls. Food hygiene problems such as waste oil and deteriorated raw materials are difficult to prevent 100%.
Olive oil is a relatively healthy edible oil, mainly because it contains high unsaturated fatty acids, which can reach 75% to 90%. Unsaturated fatty acids are helpful to maintain the health of cardiovascular and cerebrovascular diseases, but unsaturated fatty acids are not resistant to high temperature. In daily cooking, if you choose to use olive oil in high-temperature ways such as frying and barbecue, the unsaturated fatty acids contained in it are easily oxidized and denatured.
Even if fried in this way, the loss of unsaturated fatty acids will be more serious if it takes a long time. So generally speaking, for olive oil with high unsaturated fatty acid content, it is recommended to eat it cold. Of course, there are different grades of olive oil. The higher the quality of olive oil, the less it is recommended to cook at high temperature.