On September 13th, after nearly three months of hard work, the Beijing Food Safety Monitoring Center comprehensively screened more than 80 technical inspection items that may be involved in the production of waste oil, and finally found four types of effective indicators for the detection of waste oil. An index system for the detection of waste oil was established. While the Ministry of Public Security undertook the cracking of Zhejiang Luyu and other places to use cooking oil for the sale of edible oil, the Beijing Food Safety Monitoring Center, based on previous research, played a qualitative role in determining the waste oil found in the case and identified the trenches. The harm of oil to the human body plays a necessary technical support.

3 months initial establishment of detection index system
“At present, China has not specifically targeted the testing standards for waste oil.” Lu Yong, director of the Beijing Food Safety Monitoring Center, told reporters whether the inspection of edible oils is qualified and safe, based on the “edible vegetable oil” that was implemented on October 1, 2005. health standard". However, this standard is usually used to determine whether the company's normal production of edible oil is qualified, and did not take into account the extremely harsh "production" method of "drift oil" in advance, therefore, the existing national standard can not be used to determine whether the oil belongs to the trench oil.

Drain oil is a collective name for various waste edible oils and fats. The state clearly stipulates that waste oils must not be processed and used as edible oils and fats or sold. However, driven by interests, individual unscrupulous companies or individuals will waste oil processed through “underground channels” and pose a threat to consumers’ table safety. Since China has not yet established a complete set of technical specifications for the identification of waste oil, it is difficult for the regulatory authorities to identify whether there is a waste oil in the market.

Since June of this year, the Beijing Food Safety Monitoring Center has organized experts from the city’s physical and chemical analysis and testing centers, the State Environmental Protection Product Quality Supervision and Inspection Center, the National Food Quality and Safety Supervision and Inspection Center, Peking University, and the China Agricultural University. Identification technology for assessment. In nearly three months, the inspectors have comprehensively applied modern analytical testing methods such as chromatographic analysis, spectral analysis, physicochemical analysis, and gene identification technologies to carry out technical research on the identification of waste oil, and successively performed more than 80 technical indicators in all directions. The screening has identified four major categories of polycyclic aromatic hydrocarbons, cholesterol, electrical conductivity, and specific genes, and more than 20 items with important identification significance, and initially established an index system for the detection of waste oil.

The core secret: four types of indicators to make the original oil appearance

The first indicator: polycyclic aromatic hydrocarbons (PAHs). Polycyclic aromatic hydrocarbons (PAHs) are aromatic compounds containing multiple benzene rings that are generated after cooking oil is heated, such as frying, roasting, frying, frying, etc., and are persistent organic pollutants. Most PAHs have been listed as carcinogens by the International Cancer Research Center. .

The second indicator: cholesterol. Edible vegetable oils generally do not contain cholesterol or are extremely low in content. According to the technical staff, the waste oil may contain animal-derived components, and it is inferred that if the cholesterol is detected and exceeds a certain range, the oil may be suspected as waste oil.

The third indicator: conductivity. Normal grease is almost non-conductive, but the various polar substances produced after the rancidity of the grease can make the grease conductive. Waste oil generates electrical conductivity due to the doping of a large amount of metal ions and has a high electrical conductivity.

The fourth indicator: specific gene composition. Drain oil is a mixture of waste oils from many different sources, and often contains animal fats. The testers identify animal genes in oils and fats based on molecular biological genetic identification methods to determine whether edible oils contain animal-derived components. Dr. Zhao Linna of the testing center told the reporter: “Extracting a very small amount of animal DNA fragments from oil, which is the animal's genetic sequence, is extremely difficult and it is a technical obstacle in the world. We have tried many methods to find the extracted animal. Gene approach."

The simulation test found that there is a huge profits in waste oil

There is no sample of cooking oil, how to test? Researchers at the Beijing Food Safety Monitoring Center supported cooking pots outside the laboratory and conducted simulation experiments. The fritters, chips, chicken legs, fat, etc., were put into the pan. The researchers had repeatedly fried the peanut oil, soybean oil, etc. and left it for more than a week until the oil smelled sour. In this way, simulated real version of "drainage oil" is produced.

The technicians also used the adsorbent to remove impurities, and after some deodorization and extraction, it was found that after several treatments of “drain oil”, it was tested according to the existing edible oil national standard, and the indicators were indeed “qualified products”. More crucially, the technicians discovered that because of the cheaper materials such as adsorbents, there is indeed a huge profit behind the refinement of “oil for cooking”. According to calculations, the cost per ton of "ditch oil" to be returned to "qualified products" is only about 3,500 yuan, while the market price of edible oil is about 8,000 yuan per ton. If lawless elements adopt a simpler method, the cost can be lowered even lower.