When frying food in oil, the temperature of the oil pan is as high as 200 degrees, and the oil in the pan is undergoing complex chemical reactions. High-temperature cooking oil, especially the residual oil with repeated high temperatures, will produce carcinogens such as benzene ratio. The skin and meat of fish contain protein, amino acids and a little fat. When exposed to high temperature, they pyrolyze and produce heterocyclic compounds. The higher the oil temperature, the longer the frying time and the more heterocyclic compounds, which is a carcinogen. People can detect heterocyclic compounds in urine after eating this fried fish. Although the content is low, if long-term cooking oil is used to fry fish, meat and poultry (including chickens, ducks, geese, pigeons and quails), the amount of carcinogens will accumulate. If they eat or inhale other carcinogens and carcinogens, they may cause cancer.

Studies have found that oxidized cholesterol in fried foods can accelerate arteriosclerosis, lead to insufficient blood supply to myocardium and lead to coronary heart disease. Fast food, mainly fried meat, poultry and French fries, contains a lot of fat and calories. If you eat these foods regularly, you may be overweight or obese. It is also good for diabetes and heart disease.

In terms of food nutrients, frying makes a lot of water in food lose, while other nutrients decrease or increase. For example, the moisture content of beef was 75.57% before frying and decreased to 39.95% after frying. The content of protein decreased from 265438 0.54% before explosion to 20.00%. The lipid content increased from 2.045% before frying to 4.48%. The average loss of vitamin B 1 of various meat products after frying is 26%. The research results show that frying has little effect on the utilization rate of protein in meat products, but the above indexes will be greatly affected after frying with auxiliary materials.

From these results, it can be seen that frying makes food lose some water and increase oil content; Although the temperature of frying is high, the internal temperature of food generally does not exceed 100℃, so frying has little damage to the nutritional components of food and its nutritional value will not change much. Using reasonable technology, frying is a safer food processing method. However, there are many kinds of fried foods, and the production scale is also different. Most of the problems will appear in whether the production process is reasonable and standardized, and whether consumers eat it scientifically and reasonably. Studies have shown that when frying food, some chemicals formed by decomposition and polymerization of certain substances may have toxic effects on human body. For example, the cyclic monomers, dimers and polymers produced by frying oil can lead to paralysis, tumor and cancer. Generally speaking, this kind of safety problem is not serious when the heating temperature of frying is not high and the time is short, but if the heating temperature is too high and frying oil is used repeatedly, polycyclic aromatic hydrocarbons may be produced. In recent years, it has also been found that a large amount of acrylamide is produced in high-temperature fried foods (such as French fries). In order to reduce costs, vendors, restaurants and some restaurants often use old oil fried from sewers, which is not only carcinogenic, but also unsanitary.