food safety

There are many types of foods, and there are differences between natural foods and artificial foods in terms of the state of life of foods. As far as natural foods are concerned, some can directly cultivate new life, such as eggs, wheat, and rice seeds. Although most natural foods cannot produce new life, they contain certain biological tissues and active cells such as rice, meat, milk, fruits, and vegetables. These natural foods can produce varying degrees of biophotonic radiation. Relevant measurements and analyses can provide information about the quality of the food, such as freshness. Artificial foods are foods that are processed from biological materials, such as yogurt, cooking oil, bread, and the like. The content of living matter in these foods has been greatly reduced, and the biophoton radiation signal in the strict sense is quite low. It is generally difficult to measure and analyze with biophotonic detection technology. However, if the food being measured can extract liquid, it can be detected by electrochemiluminescence [28]. For example, when measuring pesticide residues in vegetables, the vegetables can be immersed in water for a period of time. After the residual pesticides are put into the water, the water containing the pesticides is measured by electrochemiluminescence technology, and relevant information can be obtained by this method. Of course, such measurement and analysis needs to establish a database based on the actual pesticide species. For simple inorganic and organic residues, such as organophosphorus residues, fluoroacetamide and other rodenticides, veterinary drug residues, papaverine, barbital, nitrous acid. Salt, formaldehyde, benzoic acid, sulfur dioxide, etc., need to carry out a series of measurements in the laboratory, and establish a primary or secondary database, and then gradually transfer to practical measurement and analysis. If the food contains microbial contamination, such as Salmonella in food, Listeria monocytogenes, Staphylococcus aureus, Shigella, Vibrio parahaemolyticus, Enterohaemorrhagic Escherichia coli, Enterobacter sakazakii, jejunum bending Bacteria, Bacillus cereus, and aflatoxins, botulinum toxins, algae toxins, etc., in such cases, measurement and analysis become quite complex, requiring a large number of systematic and standardized measurements in the laboratory, establishing more Level database, and constantly expand and improve the database according to actual needs, and finally establish practical standards and enter practical applications. Once the standards are established, the advantages of biophotonic technology can be fully utilized. The use of biophotonic technology to detect food quality not only gives quantitative data, but also has the advantage of being fast and sensitive. After the sample is placed in the darkroom, it usually takes only 20-30 minutes to give the result. This method is expected to play an important role in food quality testing. [Application of Biosensors in Food Hygiene Testing] The detection of microorganisms in foods has always followed the traditional plate counting method. The method is cumbersome and time consuming, and it is increasingly difficult to adapt to the needs of the food testing department. The emergence of biosensors has revolutionized the way bacteria are measured, and it has made it possible to automate the detection of microorganisms in the food industry during production and packaging. Foods that are marketed will be safer and more reliable. (1) Determination of bacteria and pathogenic bacteria in foods Microbial biosensors are used for detecting microorganisms, and have the advantages of being inexpensive, durable, convenient, and quick. However, due to the limited ability of microorganisms to directly or indirectly discharge on electrodes, there is a disadvantage of low sensitivity. In addition, since microorganisms often contain a variety of enzymes, the selectivity is not ideal. The development of fiber optic biosensors, immunobiosensors, and nucleic acid sensors opens up new avenues for microbial detection. The fiber optic sensor can be directly placed in a culture flask containing a growth solution to automatically monitor the growth of microorganisms. This sensor estimates the amount of bacteria by measuring the carbon dioxide concentration of by-products in the metabolic process of microorganisms. A fiber optic sensor coupled to a nucleic acid amplification system (PCR) can detect a small number of pathogenic bacteria in food, such as the Listeria single cell gene. A small amount of Salmonella, Escherichia coli, and Staphylococcus aureus spheres present in the food can be detected by an enzyme-coupled current type immunosensor. (2) Biosensors detect toxins in foods In various food poisonings, bacterial food poisoning occupies a large proportion. According to statistics, the annual bacterial food poisoning incidents in China account for 30% to 90% of the total number of food poisoning incidents, and the number of poisoning accounts for 60% to 90% of the total number of food poisonings. Bacterial food poisoning can be generally divided into three types: toxin type, infection type and mixed type. The food testing department urgently needs to develop a simple and quick method to conduct on-site testing of the virulence in food to protect people's health. The detection limits of several mutants AF-2, mitomycin, captan, aflatoxin B1 and nitroguanidine were 1.6, 0.5, 0.9, 0.8, μg/mL, respectively. The Ames method is not only short-lived (the former is 60 min, the latter is 2 to 3 days, and the latter is one week), and the sensitivity is also high (the minimum detection limit for AF-2 is 1.6 μg/mL, and the latter is 10 μg/mL). The working strain of the sensor is Bacillus subtilis, and the wild type (Rec+) DNA of the strain is known to be repaired by molecular recombination after being chemically damaged, so that it can continue to multiply; and the deficient bacteria that have lost this self-repairing ability (Rec) -) Death after loss of fertility after chemical damage to DNA. The Rec+ and Rec- strains were separately immobilized on the surface of a pair of oxygen electrodes to constitute a mutagenic sensor. (3) Biosensors detect residual pesticides in foods In view of the frequent occurrence of incidents of poisoning of pesticide-containing foods, the health inspection department urgently needs rapid detection technology to respond to poisoning incidents. The traditional method of analyzing pesticides not only requires expensive equipment, but also has a cumbersome method and is time consuming. It can neither be applied to the grassroots application nor to the field application, and the biosensor shows its unique advantages in this respect. The organic phosphorus pesticides methyl marathon, ethyl marathon, trichlorfon and diethyl propyl phosphate were determined by conductivity biosensor. The lower detection limits were 5×10-7, 1×10-8, 5 respectively. ×10-7, 5×10-11 mol/L. Fernando used organo-phosphorus and urethane-based pesticides to detect 10 mmol/L marathon and triamectin using an optically addressed potentiometric sensor. For other pesticides such as monocrotophos, dimethoate, dichlorvos, chlorhexidine, diazinon, aldicarb, etc., the detection concentration is higher. The sensor has a fast detection speed and can detect 8 samples at the same time in a few minutes with high accuracy and can be used repeatedly after being treated by the resuscitation agent.