The total number of colonies is an indicator of microorganisms, not pathogenic bacteria. It is mainly used to evaluate the cleanliness of food and reflect whether the food meets the hygiene requirements in the production process. The excessive total number of colonies indicates that individual enterprises may not strictly control the sanitary conditions in the production and processing process as required, or the cleaning and disinfection of packaging containers are not in place; It may also be related to lax product packaging and improper control of storage and transportation conditions.
(2) Escherichia coli
Coliform bacteria is one of the commonly used indicators of food pollution at home and abroad. The detection of coliforms in food suggests that it is more likely to be contaminated by pathogenic bacteria (such as Salmonella, Shigella and pathogenic Escherichia coli). No pathogenic bacteria were detected in the products with excessive coliforms. Based on the comprehensive analysis of factors such as residents' dietary structure and sampling situation, the health risk is low, but it reflects that the food hygiene situation is not up to standard. Excessive coliform bacteria may be caused by the pollution of processing raw materials and packaging materials of products, or the pollution of production equipment and environment such as personnel and tools during production, and the incomplete sterilization of products by sterilization technology.
(3) Escherichia coli
Mold: The main reasons for exceeding the standard of mold may be that raw materials or packaging materials are contaminated by mold, the sanitary conditions of products are not well controlled during production and processing, the equipment and facilities such as production tools and instruments are not cleaned and disinfected properly, or the storage and transportation conditions of products are improper.
Mold and yeast: The reason why mold and yeast exceed the standard may be that the processing raw materials are contaminated by mold, or that the mold and yeast in the samples taken from the circulation link exceed the standard, which is caused by improper control of storage and transportation conditions. Mould and yeast are very common in nature. Mould will spoil food, destroy its color, smell and taste, and reduce its edible value.
Pseudomonas aeruginosa is an opportunistic pathogen, which is widely distributed in all kinds of water, air, skin, respiratory tract and intestine of normal people. It is easy to survive in humid environment, and has strong resistance to disinfectants and ultraviolet rays, which poses health risks to people with weak resistance. Pseudomonas aeruginosa in natural mineral water may exceed the standard because of improper water source protection and pollution of water body; Hygienic control in the production process is not strict, such as employees' unsterilized hands directly contacting mineral water or the inner wall of containers; Or the cleaning and disinfection of packaging materials is defective.
Mycotoxin project (1) aflatoxin B 1
The unqualified aflatoxin B 1 of peanut oil product is mainly due to the following reasons: peanut raw materials were contaminated by Aspergillus flavus and other molds during planting, harvesting, transportation and storage, and enterprises did not strictly select peanut raw materials and carry out relevant tests in the production process, and enterprises did not adopt refining process or improperly control the process.
(2) Deoxynivalenol
The excessive deoxynivalenol (DON) in wheat flour may be caused by the pollution of DON to raw wheat and the lax control of raw materials by enterprises. Deoxynivalenol (DON) is one of the important indicators of grain mildew, and it is also one of the most extensive natural toxins that pollute grain and animal feed. In humid environment, more DON may be produced in barley, wheat, corn and oats contaminated by mold. People who eat cereal seriously contaminated by DON will have vomiting, diarrhea, headache, dizziness and other poisoning symptoms. Keeping grain and food dry is the key to avoid this problem.
Additive Item (1) Food Pigment
There are sweeteners (mainly sodium cyclamate, saccharin sodium, acesulfame K, etc.). ) used in food beyond the scope or beyond the limit. The reason may be that in order to increase the sweetness of products, enterprises use sweeteners beyond the limit or scope, or do not accurately measure sweeteners; Sweeteners are detected in individual honey products, and there is also the possibility of adulteration.
Preservatives (mainly benzoic acid, sorbic acid, dehydroacetic acid, etc. ) used in food beyond the scope or beyond the limit. The reason may be that the enterprise exceeds the limit and scope of use in order to increase the shelf life of the product or make up for the poor sanitary conditions in the production process of the product, or it does not accurately measure it.
There are edible pigments (mainly lemon yellow, sunset yellow, carmine, seductive red, amaranth red, brilliant blue, etc.). ) are used out of range or out of bounds. The reason may be that the enterprise has added too much in order to increase product sales, or to make up for the low quality of raw materials, or has not been accurately measured. Adulteration cannot be ruled out if the edible pigment of individual products exceeds the standard.
(2) aluminum residue
Aluminum-containing food additives (such as alum) are legal food additives and will not cause harm to health if used according to standards. According to the risk assessment results of dietary aluminum exposure of China residents completed by the National Food Safety Risk Assessment Expert Committee, it is unlikely that aluminum-containing foods in our daily diet will have adverse effects on the health of ordinary residents, but consumers who eat high-aluminum foods for a long time should pay attention. The reason why the aluminum residue exceeds the standard may be that individual enterprises use aluminum-containing additives in the production and processing process in order to improve the taste of products, or the aluminum content in the composite additives they use is too high.
(3) Sulfur dioxide
Sulfur dioxide is a common bleaching agent and preservative in food processing. After entering the human body, it will eventually be converted into sulfate and excreted with urine. A small amount of sulfur dioxide will not bring health hazards to human body, but excessive consumption will cause gastrointestinal reactions such as nausea and vomiting. The reason why sulfur dioxide is not up to standard may be that individual producers use inferior raw materials to reduce costs, and then use too much sulfur dioxide to improve the color of products; It is also possible that it was not measured or allowed when it was used; It is also possible to increase the shelf life of spices, prevent mildew and insects, illegally fumigate or add sulfur dioxide.
(4) dehydroacetic acid
Dehydroacetic acid and its sodium salt, as broad-spectrum food preservatives, have low toxicity, and are safe and reliable to use according to the range and dosage specified in the standard. The reason why dehydroacetic acid exceeds the standard may be that individual enterprises use the additive excessively to prevent food corruption, or the compound additive used by them has a high content of the additive; It may also be that it was not measured or inaccurate during the addition process.
(5) Natamycin
Natamycin is a food preservative, which is basically non-toxic after entering the human body and is not easily absorbed by the digestive tract. The reason why natamycin exceeds the standard may be that individual enterprises use the additive excessively to prevent food spoilage, or the compound additive used by them has a high content of the additive; It may also be that it was not measured or inaccurate during the addition process.
Acid value (price) of quality project (1)
Acid value (valence) mainly reflects the rancidity degree of oil in food. The main reasons for the unqualified acid price (price) are: the raw material procurement is not strict, such as the high moisture content of edible vegetable oil, roasted seeds and nuts, which will accelerate the rancidity of oil; The production process is not up to standard, such as refined vegetable oil is not in place or not refined; Improper storage conditions of products, especially in summer, are more affected by climate and environment, which easily leads to oxidative rancidity of fats in food. Long-term intake of aldehydes and ketones produced by rancidity of oil will have a certain impact on health, but in general, consumers can clearly distinguish the odor such as halo during use and need to avoid eating it.
(2) Electrical conductivity
Electrical conductivity is an index to measure the purity of water. The possible reasons for the unqualified indicators of this kind of products are: problems in the production process, lax process control, long-term failure to replace the reverse osmosis membrane and incomplete cleaning of the filtration equipment.
(3) peroxide value
The peroxide value mainly reflects whether the oil is oxidized. With the oxidation of oil, the peroxide value will gradually increase. Although it will not endanger human health, it will cause symptoms such as gastrointestinal discomfort and diarrhea in severe cases. The reason why the peroxide value exceeds the standard may be the deterioration of refined oil, or the improper control of environmental conditions during storage of products, which leads to the rancidity of oil products; It may also be that the fat in the raw materials has been oxidized, the raw materials have not been stored properly, and effective anti-oxidation measures have not been taken, which makes the final refined oil oxidized. In addition, insufficient refining of vegetable oil may also lead to unqualified peroxide value of edible oil, grease and its products.
(4) Volatile basic nitrogen
Volatile basic nitrogen is an indicator of animal food spoilage. The higher the content of volatile basic nitrogen, the more amino acids are destroyed, and the greater the impact on nutritional value. Volatile base nitrogen exceeds the standard, indicating that raw meat for production may not be fresh; It may also be that the hygienic conditions of meat products are improperly controlled and contaminated by bacteria during the curing process, which leads to excessive standards.
(5) Alcohol content
Alcohol, also called alcohol degree, refers to the number of milliliters of ethanol (alcohol) contained in 100 ml wine at 20℃. Alcohol content is an important physical and chemical index of liquor products, and the unqualified alcohol content mainly affects the product quality. The unqualified alcohol content may be that the production process of individual enterprises is not strictly controlled or the production technology level is low, which can not effectively control the alcohol content; It may also be that individual enterprises deliberately raise the alcohol content in order to reduce costs, so as to increase the sales price and deceive consumers; It also does not rule out that the manufacturer's testing instruments are inaccurate and the test results are biased.
(6) Amino acid nitrogen
Amino acid nitrogen is one of the characteristic quality indexes of soy sauce. The higher the amino acid nitrogen content, the better the quality of soy sauce and the stronger the umami flavor. The unqualified amino acid nitrogen mainly affects the flavor of the product. The content of amino acid nitrogen is not up to standard, which may be because the production process of the product does not meet the standard requirements and the required fermentation time is not reached; It may also be a problem of product formula defects; There may also be cases where individual enterprises deliberately adulterate in order to reduce the cost in the production process.
Other project (1) clues
Lead belongs to the index of heavy metal pollutants, which is mainly brought into raw materials by environmental pollution, indicating that the production enterprises are not strict with raw materials, and the use of raw materials with excessive lead content does not rule out the possibility of migrating from production equipment to food.
(2) Bromate
Bromate is a by-product produced by drinking water producers when ozone is used to disinfect raw water. At present, there is no conclusion about its carcinogenic harm to human body in the world. Bromate content in packaged drinking water is mainly related to bromide content in water source or the amount of ozone used in disinfection. If the bromide content in the water source is high or the ozone addition is large, the final product bromate may exceed the standard.
(3) benzopyrene
The main reason for benzopyrene exceeding the standard may be improper temperature control or unreasonable processing time during production and processing, or improper storage or drying of raw materials.
(4) rhodamine b
Rhodamine B is a bright pink synthetic dye, which has been listed in the List of Abuse-prone Non-edible Substances and Food Additives in Food (the first batch) and is not allowed to be used in food. The detection of rhodamine B reflects that it is likely that the enterprise illegally added the substance to make the product shine, and it does not rule out that the substance was added to the purchased raw materials.
Common methods of food safety detection chromatographic techniques The commonly used methods in chromatography include gas chromatography, high performance liquid chromatography, thin layer chromatography and immunoaffinity chromatography.
Gas chromatography can accurately and sensitively carry out rapid qualitative and quantitative analysis, and is widely used in the detection of natural toxins, pesticides, food additives and veterinary drugs in food safety detection. Thin-layer chromatography is a separation and analysis method developed in 1930s. The instrument is simple, convenient and widely used, but its sensitivity is not high. Thin layer chromatography is widely used in pesticides, toxins, food additives and so on, and plays an important role in qualitative, semi-quantitative and quantitative analysis. Mass spectrometry is an analytical method to measure the charge-mass ratio of ions. As an ideal chromatographic detector, mass spectrometry has strong specificity and high detection sensitivity. Chromatography and mass spectrometry combine their advantages and become the research focus of 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 matter, while the latter is usually used for the analysis of samples with high polarity, strong thermal stability and difficult volatilization.
Spectral analysis is a method based on the emission and absorption of electromagnetic radiation by substances and the interaction between substances and electromagnetic radiation. It is a method based on spectral measurement through the internal relationship and manifestation between radiant energy and the composition and structure of matter. It is also a nondestructive, rapid and low-cost detection technology. Among them, Raman spectrum, infrared spectrum, near infrared spectrum and fluorescence spectrum are widely used in food safety detection.
Biotechnology Biological detection technology has developed rapidly in recent years and attracted much attention in food detection. Because most foods come from natural organisms such as animals and plants, they naturally have the ability to distinguish between substances and reactions. Biotechnology uses the reaction between biological materials and chemical substances in food to achieve the purpose of detection, which shows great application potential in food inspection, with the advantages of specific biometric function, high selectivity, accurate, sensitive, specific, trace and rapid results. Widely used methods include enzyme-linked immunosorbent assay, PCR, biosensor and biochip technology.
Enzyme-linked immunosorbent assay (ELISA) is an immunoassay method based on immunoenzymology, which combines the high specificity of antigen-antibody reaction with the efficient catalysis of enzyme. Its basic principle is that the enzyme-labeled antigen or enzyme-labeled antibody is used as the main reagent, and the substance to be detected is determined qualitatively or quantitatively through the enzyme-catalyzed substrate color reaction in the complex, which is widely used in the food safety detection of agricultural and veterinary drug residues, illegally added substances, biotoxins, pathogenic microorganisms, genetically modified foods and so on. Such as the determination of enrofloxacin, clenbuterol, Proteus mirabilis, alkalophilic and salt-tolerant. PCR technology, that is, polymerase chain reaction technology, is a method of enzymatic synthesis and amplification of specific DNA fragments in vitro. It is a useful tool to investigate the outbreak of food-borne diseases and identify the pathogens. Because of its strong specificity, high sensitivity, accuracy and rapidity, it has been widely used in the field of food detection. Biosensor is a kind of physical sensor that combines biometric elements with target substances. It has the advantages of high specificity, high sensitivity, fast reaction speed and low cost, and has become an important tool in food detection. Mainly used for the detection of food additives, pathogenic bacteria, pesticides and antibiotics, biotoxins, etc. Such as rapid determination of nitrite, Salmonella typhimurium, organophosphorus and carbamate, aflatoxin B 1 in food. Biochip method is a brand-new microanalysis technology integrating molecular biotechnology, micromachining technology, immunology, computer and other technologies. The analysis process is integrated on the chip to realize the continuity, integration, miniaturization and informatization of sample detection. In food safety detection, it can be applied to the detection and analysis of food-borne microorganisms, viruses, drugs, mycotoxins and genetically modified foods.