Detection technology for food safety testing

Chromatography technology is essentially a physical and chemical separation method, that is, when two phases move relative to each other, because different substances have different distribution coefficients (or adsorption coefficients) in the two phases (stationary phase and mobile phase), through continuous distribution (That is, the components undergo repeated dissolution, volatilization or adsorption and desorption processes between the two phases) to achieve the purpose of separating each substance. Chromatographic technology has matured and has the advantages of high detection sensitivity, high separation efficiency, high selectivity, low detection limit, low sample consumption, convenience and speed, etc., and has been widely used in safety testing in the food industry. Commonly used methods in chromatography include gas chromatography, high performance liquid chromatography, thin layer chromatography and immunoaffinity chromatography.

Gas chromatography can perform rapid qualitative and quantitative analysis accurately and sensitively, and is widely used in food safety testing to detect natural toxins, pesticides, food additives, veterinary drugs, etc. Thin-layer chromatography is a separation and analysis method developed in the 1930s. The instrument is simple to operate, convenient and widely used, but its sensitivity is not high. Thin layer chromatography is widely used in pesticides, toxins, food additives, etc., and plays an important role in qualitative, semi-quantitative and quantitative analysis. Mass spectrometry is an analytical method that measures the charge-to-mass ratio of ions. As an ideal chromatographic detector, mass spectrometry is not only specific but also has extremely high detection sensitivity. Chromatography and mass spectrometry technology combines the advantages of both and has become a research hotspot in analytical chemistry. Among them, gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) are widely used. The former is used for qualitative and quantitative analysis of organic substances, while the latter is usually used for polarity and thermal stability. Analysis of highly volatile and difficult-to-volatile samples. Spectral analysis is a method established by utilizing the emission and absorption of electromagnetic radiation by matter and the interaction between matter and electromagnetic radiation. It is formed based on spectral measurement through the intrinsic connection and manifestation between radiant energy and material composition and structure. Methods. Spectral analysis is a non-destructive and rapid detection technology with low analysis cost. Among them, Raman spectroscopy, infrared spectroscopy, near-infrared spectroscopy and fluorescence spectroscopy are widely used in food safety testing.

Near-infrared light refers to electromagnetic waves with wavelengths between the visible region and the mid-infrared region, with wave numbers ranging from 12500 to 4000cm. Near-infrared spectroscopy (NIR) analysis technology is an indirect analysis technology that performs qualitative or quantitative analysis of samples by establishing a calibration model. Near-infrared spectroscopy technology has the advantages of high speed, no need to prepare samples, and low cost, and has been widely used in food safety analysis. Raman spectroscopy technology is a vibration mode based on bond extension and bending, which uses the intensity of scattered light and Raman shift mapping to obtain information. In food safety testing and analysis, the substance to be measured can be qualitatively analyzed, and the content of food ingredients can also be quantitatively detected. Hyperspectral imaging technology is a new technology developed in the 1980s. It integrates image information and spectral information and has been widely used in the quality and safety testing of agricultural and livestock products and food. Biological detection technology has developed rapidly in recent years and has attracted much attention in food testing. Since most foods come from natural organisms such as animals and plants, they naturally have the ability to identify substances and react. Biotechnology that uses biological materials to react with chemical substances in food to achieve detection purposes shows great potential in food inspection. It has specific biorecognition functions, high selectivity, accurate results, sensitivity, specificity, trace amounts, and rapidity. Etc. The more widely used methods include enzyme-linked immunosorbent technology, PCR technology, biosensor technology, and biochip technology.

Enzyme-linked immu-nosorbent assay (ELISA) is an immunoassay method based on immunoenzymology that combines the high specificity of antigen-antibody reactions with the efficient catalysis of enzymes. . The basic principle is to use enzyme-labeled antigens or enzyme-labeled antibodies as the main reagent, and use the enzyme-catalyzed substrate color reaction in the complex to characterize or quantify the test substance. It is widely used in food safety testing such as pathogenic microorganisms and genetically modified foods, such as the determination of enrofloxacin, clenbuterol, and alkaliphilic and salt-tolerant Proteus mirabilis. PCR (polymerase chain reaction) technology, also known as polymerase chain reaction technology, is an in vitro enzymatic synthesis method to amplify specific DNA fragments. It is a useful tool for investigating food-borne disease outbreaks and identifying responding pathogenic bacteria. It is characterized by its specificity. It has the advantages of strong performance, high sensitivity, accuracy and speed, and is widely used in the field of food testing.

Biosensor is a physical sensor that combines biological recognition elements with target substances. It has the advantages of high specificity and sensitivity, fast response speed, and low cost. It has become an important tool in food testing. Mainly used in the detection of food additives, pathogenic bacteria, pesticides and antibiotics, biotoxins, etc. Such as the rapid determination of nitrite, Salmonella typhimurium, organic phosphates and carbamates, aflatoxin B1, etc. in food. The biochip method is a new micro-analysis technology that integrates molecular biotechnology, micro-processing technology, immunology, computer and other technologies. It integrates the analysis process on the chip to achieve continuous, integrated, miniaturized and information-based sample detection. change. In food safety testing, it can be used to detect and analyze food-borne microorganisms, viruses, drugs, mycotoxins, and genetically modified foods. Food safety hazards and food safety issues are becoming increasingly serious. With the promulgation and implementation of the "Food Safety Law of the People's Republic of China", people's attention and concern for food safety are also increasing, and food safety supervision has become a new concern. focus. Many food safety incidents have occurred in China, such as the Qingdao poisonous leek incident in 2001, the clenbuterol incident in 2001, etc. These food safety issues directly threaten people's health and life safety. The "Food Safety Law of the People's Republic of China" clearly states that food safety supervision should be implemented from farm to table, which poses a major problem for government law enforcement agencies.

Domestic food safety regulatory authorities have gradually adjusted their supervision models, shifting from departmental supervision to technical supervision. Issues such as the accuracy of detection and the speed of detection in technical supervision are urgent issues that need to be resolved. Rapid food testing technology is the precursor of technical supervision. As the main means to ensure food safety, it has attracted more and more attention from regulatory authorities. Due to the extensive use of pesticides, hormones, antibiotics in food raw materials, as well as toxic and harmful substances illegally added during processing, food poisoning incidents occur frequently, are sudden and spread quickly, and traditional detection methods can no longer meet the needs of rapid supervision and early warning. Food rapid testing technology is compared with traditional inspection and testing. Rapid detection technology is used to screen samples on site, which is characterized by qualitative detection of relative hazard indicators. The detection speed is fast, which can win time and eliminate food safety hazards. Although product laboratory test results are accurate and reliable, the cycle is long, the cost is high, and the operation is cumbersome.