"Waste oil" is also called "crude oil" by people in the industry. There are three main sources: one is the oil dumped with leftovers in swill, that is, swill oil; The second is the oil used to fry food, that is, the re-fried oil; The third is the oil bottom of cooking and the oil discharged into the sewer with the brush pot water. In addition, there is a new type of gutter oil, which is different from traditional gutter oil. It is mainly made by simply processing and refining inferior, expired and corrupt animal skins, meat and internal organs.

According to He Dongping, a professor at the School of Food Science and Engineering, Wuhan Institute of Technology, there are 2-3 million tons of waste oil returning to the dining table every year in China. According to the proportion, for every 10 meal, 1 meal may encounter gutter oil. Once the waste oil flows into the table, there will be endless troubles. Especially the "new waste oil", most rotting animals contain germs themselves. After being bitten by mosquitoes and flies, it contains a lot of toxic components, which directly threatens human health.

The main hazard of "gutter oil" is aflatoxin, which is a strong carcinogen, and its toxicity is about 10 times that of potassium cyanide and 100 times that of arsenic.

The biggest harm of gutter oil lies not only in carcinogenic aflatoxin, but also in repeated heating and oxidation. Liquid vegetable oil is not heat-resistant, and the frying temperature can be as high as 160℃-300℃. When oil is heated, trans isomerization, thermal oxidation, thermal cracking, cyclization, etherification, polymerization and other reactions will occur. After cooking oil is repeatedly heated by frying, roasting, frying and frying, it will produce polycyclic aromatic hydrocarbons, which is very harmful to adults and DNA mutation, and has a strong teratogenic effect on fetuses.

The extracted gutter oil is almost pure, similar to the principle of refining gasoline from crude oil. At present, no country in the world can accurately detect gutter oil, because gutter oil itself has not found detectable characteristics. Food poisoning is basically not a problem of gutter oil, but caused by bacteria. We just can't stand it ethically and legally, so safety will be fine. I hope that regulators will keep their eyes open and protect the people's table.