Commonly used rapid detection technology for food

There are many sales channels for agricultural products and food in China, and the level of food safety varies from place to place.

1.

The detection principle of immunoassay is based on the serological detection method in medicine, which uses the highly specific and specific reaction of antigen and antibody for detection

Immunoassay methods include radioimmunoassay, enzyme-linked immunoassay, fluorescence immunoassay, chemiluminescence immunoassay, and colloidal gold-labeled immunoassay

The shortcomings of immunoassays are due to the specificity of the antigen-antibody reaction.

2.

The colorimetric analysis method is based on the chemical characteristics of the components to be tested in the food, so that the components to be tested and specific reagents have a specific color reaction, and then compare the color with the standard product or compare the absorbance with the standard product at a certain wavelength to obtain the final result

Molecular spectroscopy is the most classic technique, which can be used for almost all detection tasks, but generally it can only perform constant or trace detection, and it is difficult to undertake the task of trace analysis

In recent years, Jade Swan and Huaxia Science and Technology, etc.

3.

The enzyme inhibition method was proposed by the U.

4.

The biosensor is composed of a biosensing element and a sensor closely connected or combined with it

(1) Developed countries have widely used the strong combination of surface plasmon resonance analyzer (SPR) with many other new technologies, and launched a batch of new rapid screening and detection methods and instruments, which are characterized by: sensitive, fast, and no marking , Convenient and real-time

(2) It has recently been reported that the United States has developed a new type of biosensor using nanotechnology, which can quickly and highly sensitively detect very small amounts of bacteria, viruses, parasites, pathogens, etc.

(3) Microbial sensors, which are particularly represented by highly sensitive luminescence reactions with toxic substances

The shortcomings of this kind of methods are that some identification components have problems in long-term stability (reliability and consistency).
Most of them are currently in the development stage and still far from mass production
.

5.
Biochip, microchip laboratory and portable microfluidic chip technology.
The so-called biochip technology is relative to computer chips.
Computer chips process electronic information, while biochips process information carried by biomolecules
.
The advantage of the biochip method is a high degree of automation, can achieve the purpose of detecting multiple target molecules at the same time, and the detection efficiency is high, and the detection cycle is short
.
The disadvantage of this method is that a large amount of DNA fragment information is required in the early stage, and the detection cost is still high
.
Yuzi biochip was originally used for DNA sequence determination, so it is also called gene chip, but currently this technology has been applied in non-nucleic acid fields such as protein
.
At present, it can be divided into gene chip, protein chip and so on according to the classification of the detection object
.
According to the preparation technology standard, it can be divided into lattice chip and laboratory chip
.
Gene chip is an array of DNA molecules formed by using many specific oligonucleotide fragments or gene fragments as probes, which are regularly arranged and fixed on a support
.
Its working principle is to detect the gene of the sample according to the principle of base pairing, which is to use nucleic acid of known sequence to hybridize nucleic acid of unknown sequence
.
DNA probe technology belongs to the lattice gene chip, which prepares single-stranded DNA with a known base pair sequence on a glass or plastic silicon substrate
.
It has been applied to the detection of pathogenic bacteria in food and the detection of genetically modified food
.
The laboratory gene chip integrates sample preparation, qualitative and quantitative analysis and other processes on the chip through miniaturization technology such as the production of integrated circuits, so that the analysis process is miniaturized and continuous, and the biological analysis speed is greatly accelerated
.

This kind of technology has the characteristics of high throughput, high sensitivity and rapidity, so it has paid great attention to its application in food safety and disease diagnosis in the world
.
China's National Biochip Center has developed a biochip technology platform (instruments and kits) for the detection of food-borne pathogens, food-borne viruses, and veterinary drug residues, and will further conduct rapid testing or miniature on-site testing.
The development of the lab-on-a-chip
.
Parallel to the above, although chip technology is also used (but generally medium or low-density chips), many other new technologies are applied at the same time, thus forming an independent branch, which is called "microfluidics" and "micro-full analysis" in the world.
"Technology" is often called a portable microfluidic chip system or a micro-total analysis system in China
.
The development in recent years has highlighted its huge potential in the fields of biochemistry, food safety, inspection and quarantine, medical and other life sciences.
Foreign countries are vigorously developing industrialization, such as Caliper, Micronics&PATH, Agilent and other companies, and there are Chinese companies in China.
The Chinese Academy of Sciences, Zhejiang University, Jilin University, Chinese Academy of Sciences and other related units are under research and development
.

6.
Miniaturized and intelligent electrochemical sensor technology modified by nanomaterials

Electrochemical sensors have the advantages of compactness, sensitivity, diversification, high selectivity, simultaneous rapid measurement of multiple targets and low cost.
Special electrochemical sensors can be used to construct food safety rapid detectors
.
Current research and development are mostly focused on the production and industrialization of carbon nanotubes and graphene sensors.
Changchun Institute of Applied Chemistry and East China Normal University have organically combined nanotechnology and electrochemical technology to establish a rapid detection of toxic foods.
, Hazardous heavy metal equipment; At the same time, using a new type of nano-peroxide sensor and nano-metal/oxide sensor, a rapid detection instrument for the rapid detection of the total number of bacteria and E.
coli has been constructed
.

7.
Near infrared and Fourier transform infrared spectroscopy

Near-infrared and Fourier transform infrared spectroscopy uses the relatively strong penetrating ability of infrared light, and the hydrogen-containing groups in the sample selectively absorb near-infrared light of different frequencies, so the transmitted infrared light is carried The information of the structure and composition of the organic substance can be determined by analyzing the optical density of the transmitted or reflected light by the detector
.
This type of method is often used for on-line control of production.
Its advantages are low detection cost, fast analysis speed, no pre-processing, eliminating many influencing factors in chemical reactions, and avoiding environmental pollution; it realizes non-destructive testing of samples , And can detect multiple components of the sample at the same time
.
Its disadvantages are that it is not suitable for trace analysis, its sensitivity is lower than that of colorimetry, and it needs to establish a related model database, which requires a lot of preliminary work
.
NIR technology is already used in more mature index-line detection of moisture in the product, protein, fat content, etc.
, we have been able to detect products including grain, meat, milk, vegetables, fruits, oils, beverages
.

8.
Bioluminescence detection method

The bioluminescence detection method uses ATP to be released when bacterial cells are lysed.
After ATP is released from bacterial cells, luciferin and luciferase can be used to release energy.
These energy produce phosphorescence, and the intensity of light represents The amount of ATP, thereby inferring the total number of colonies
.
The U.
S.
NHD company introduced the Profile~13560 of the ATP food bacteria rapid detection system to separate non-bacterial cells and bacterial cells through a cuvette with a mesh at the bottom.
When the bacterial cells cannot pass through the cuvette, the bacterial cell release solution is used to lyse Bacterial cells, the amount of ATP released by detection is the amount of ATP of the bacteria, and the total number of bacteria is obtained
.
This detection system is compared with the standard culture method, the correlation coefficient is more than 90%, and the measurement only takes 5 minutes.
This method has been adopted by the US military
.
Channscience Inc.
of the United States has a series of products that control different food hygiene and safety by detecting the amount of ATP in bacteria, such as Poctetswab Plus for testing the surface of food, WaterGieneTM for testing the surface of aquatic products, Charm CHEF for testing raw meat, etc.
, the operation method is to use a special drug swab Scrape the part to be tested, then put the swab into the pen-shaped tube, and insert the portable tester to read
.

9.
Physical property testing method

The portable alcohol content rapid tester invented by Wang Lin and Zhao Hao is similar in appearance to a refractometer, consisting of a lens barrel, a detection prism, a cover plate, a light tube, a diopter adjustment ring, an eyepiece, and a content scale dividing plate
.
Its detection principle is that as the concentration of ethanol in water increases, its refractive index also rises regularly.
When methanol is present, the refractive index will decrease as the concentration of methanol increases
.
When detecting, just apply the liquid to be tested on the detecting prism and read the methanol content directly through the eyepiece
.

Related Links: Overview of Fast Food Testing Technology