Key points in food safety (organized)

Key review content:

1. Properties of food contaminants, properties of persistent organic pollutants POPs

Food contaminants classified by nature

• Biological hazards (maximum hazard) (bacteria and bacterial toxins (non-pathogenic and pathogenic bacteria), molds and mycotoxins (such as aflatoxins AFB), parasites and eggs (such as roundworms), enteroviruses (such as Hepatitis A virus), unconventional pathogens: pathogenic prion protein particles)
• Chemical hazards (important factors) (Pesticide residues: insecticides, fungicides, herbicides, biological regulators (fertilizers, veterinary drugs); toxic and harmful metals: cadmium, mercury, lead, arsenic; organic compounds: polycyclic aromatic hydrocarbons, N - Nitroso compounds, heterocyclic amines, dioxins and similar substances; food additives: excessive use and non-legal food additives;)
• Physical hazards (radioactivity) (mainly from the mining and smelting of radioactive materials, applications and emissions in production and life, as well as nuclear explosions and accidents, etc., among which the pollution of radionuclides with long half-lives is the most important.)

There are three properties of POPs: ① Toxicity; ② Bioaccumulation; ③ Mobility.

POPs members: ① those that have been discontinued: aldrin, dieldrin, toxaphene, PCB; ② those that will be discontinued: DDT, HCB; ③ those that are still in use: DDT (used in some areas), chlordane , heptachlor; ④ Unintentionally generated substances: dioxins (PCDD/PCDF).

2. Metabolism of aflatoxin in the body

• acute toxicity
  • AFB1 is extremely toxic, with an LD50 of 0.24mg/kg.bw.
  • Acute toxic effects: Mainly manifested as liver toxicity. The most sensitive animal is ducklings. Characteristic pathological changes in the liver occur: ① necrosis of liver parenchymal cells; ② bile duct hyperplasia; ③ delayed disappearance of liver cell lipids; ④ liver bleeding.
• chronic toxicity
  • Liver histological changes: hepatocyte degeneration, necrosis, regenerative nodules, bile duct epithelial proliferation, liver fibrosis, and cirrhosis;
  • Changes in liver function: serum aminotransferases, alkaline phosphatase, and globulin increased, and albumin and non-protein nitrogen decreased;
  • Other symptoms: Chronic poisoning of animals manifests as growth retardation, weight loss, reduced food utilization, female infertility or fewer litters, etc.
• Carcinogenicity
  • Animals: Long-term low doses or short-term high doses can induce experimental liver cancer in animals. The carcinogenicity is related to the metabolic formation of 2,3-epoxide, which can undergo an addition reaction with DNA guanine bases, causing DNA damage, causing mutations and carcinogenesis.
  • Humans: Although there is no direct evidence, epidemiological results indicate that AFB1 pollution is closely linked to liver cancer.

3. Common types of mycotoxin contamination and control measures

Common mycotoxins

• • Aspergillus: aflatoxin, ochratoxin, variegated aspergillus;
  • Penicillium genus: patulin, chrysanthemum, isopenicillin, Huangtianjing, citrinin;
  • Fusarium: trichothecenes, zearalenone, butenolide, Fusarium moniliforme toxin.

Mildew prevention is the fundamental measure

• • Farming stage: prevent insects and dry in time;
  • Storage stage: ① Control moisture: The safe moisture content of grain should be less than 13%, corn should be less than 12.5%, and peanuts should be less than 8%; ② Cooling: the ambient temperature should be kept below 10°C; ③ Deoxygenation: increase N2 and CO2 in the granary;
  • Chemical methods: Drugs to prevent mildew.

Detoxify

• • Select mold particles;
  • Physical methods: ① Rolling and rolling processing method; ② Adding water and scrubbing; ③ Adsorption method;
  • Chemical method: Oil can be refined with alkali, or dimethyl ether can be used to remove AFB1 from vegetable oil;
  • Other methods: high pressure destruction, ozone, microbial detoxification.

Development of hygienic standards for food mycotoxins

• • Limits of mycotoxins in food: GB2761-2005, replacing the original GB2761-1981 (allowable amount of aflatoxin B1 in food) and several other standards for mycotoxins in food;
  • Deoxynivalenol
  • Patulin

4. Bacterial contamination of food and control measures

1. Sources of bacterial contamination

• Through water contamination (Various natural water sources (surface water and groundwater) are the main ways for bacteria to contaminate food; processing food with unclean water with high bacterial counts will cause food contamination.)
• Through air pollution (bacteria in the air enter food with dust flying and settling; human sputum, nasal mucus and saliva contain a certain amount of bacteria, which can directly or indirectly contaminate food when talking, coughing and sneezing; food is directly exposed There is a chance of bacterial contamination in the air.)
• Contamination through humans and animals (employees who are in direct contact with food bring bacteria attached to them into food through their hands, work clothes, work caps, etc. and cause contamination; rats, flies, cockroaches and other animals are the main spreaders of bacteria.)
• Contamination through utensils and debris (packaging items and transportation tools used for food raw materials; processing equipment in the production process;
• Packaging materials and containers for finished food products. )

5. Meat spoilage and oil spoilage

(1) Meat spoilage:

It goes through 4 processes: stiffness, after-ripening, autolysis, and putrefaction.

--After the livestock has just been slaughtered, its meat is slightly alkaline (pH 7.0~7.4). The glycogen and phosphorus-containing organic compounds in the muscles are decomposed into lactic acid and free phosphoric acid under the action of tissue enzymes. When the pH is 5.4 , reaching the isoelectric point of myosin, myosin begins to solidify, causing muscle fibers to stiffen and become stiff.

At this time, the taste of the meat is poor, with an unpleasant smell, and the broth is turbid, not fresh and fragrant.

--Glycogen continues to decompose, the pH value further drops, the muscle connective tissue becomes soft and has a certain elasticity, the meat is soft and juicy, delicious and aromatic, and a shiny film is formed on the surface due to protein coagulation, which has the effect of preventing microorganisms from invading the interior. This process is called post-cooking of livestock meat , commonly known as acid removal.

The post-ripening process increases the flavor of the meat and prevents the invasion of microorganisms. Lactic acid has a bactericidal effect.

If livestock are overtired, the meat will not mature well after slaughter and will produce less acid, making it difficult to inhibit the growth of bacteria, leading to spoilage of the meat.

--Tissue enzymes in meat catalyze the decomposition of proteins and fats, which is called autolysis.

Conditions are edible and require high-temperature processing.

--Meat undergoes spoilage under the action of bacterial enzymes.

Consumption is not allowed.

(1) Oil rancidity

Fatty acid rancidity is related to factors such as ultraviolet rays, oxygen, moisture and tissue residues in the oil, microbial contamination, etc., and is also related to the degree of unsaturation of the oil itself. Copper, iron, and manganese can promote the oxidation process of fatty acids. The aldehydes, ketones, lower fatty acids and keto acids produced by the cleavage of the carbon chains of unsaturated fatty acids give the oil a strong pungent odor.

Commonly used indicators of rancidity include acid value, peroxide value, carbonyl value, and malondialdehyde content.

6. Temperature and temperature detection of food preservation (see Chapter 10 of "Nutrition and Food Hygiene")

Grains and legumes: Most insects will stop breeding when the storage temperature is below 10°C;

Vegetables and fruits: The general suitable temperature is 0℃

Fish, milk: refrigerated

7. BSE disease (Note: See page 418 of "Nutrition and Food Hygiene")

Also known as "bovine spongiform encephalopathy (mad cow disease)" - one of the newly recognized neurological diseases.

Prion diseases: Bovine BSE, sheep Scrape, human v-CJD (variant Creutzfeldt-Jakob disease), and PNG Fore tribe Kuru disease

Mechanism: The normal protein PrPc in brain tissue is transformed into pathogenic protein particles PrPsc. The latter is enzyme resistant and difficult to degrade, leading to the continuous accumulation of PrPsc and causing pathological changes in brain tissue.

Beef tissues with higher risk of transmitting Prion disease: intestinal tissue, brain tissue, spinal cord, tonsil glands, spleen

8. Properties of dioxin

Physical and chemical properties

• Thermal stability: Degradation temperature is 800℃, extensive damage must reach above 1000℃;
• Low volatility: A small amount floats in the atmosphere in the form of aerosols and can persist after settling on the ground;
• Lipid solubility: The food chain is the main pathway for its transfer and bioaccumulation through lipids;
• High stability in the environment: average half-life is about 9 years.

9. Production of heterocyclic amines

Formation and influencing factors of heterocyclic amines in food

• • Precursor substances: Amino acids, creatine, and creatinine in meats with high protein content are the main precursor substances; creatine is an essential precursor, and low-creatine and high-protein foods (offal, milk, beans) are mixed during cooking. Less cyclic ammonia;
  • Temperature: 100~300℃ high temperature. The cooking methods of pan-frying, deep-frying, broiling, and roasting will cause more formation, while cooking with water will reduce it;
  • Time: The content of meat is very high in the first 5 minutes of the frying process, and it tends to decrease as the cooking time increases.

10. Properties and sources of polycyclic aromatic hydrocarbons

Sources of PAHs

• Sources in the environment: incomplete combustion of organic matter (wood, coal, oil); wildfires, garbage burning, cigarette smoke;
• Sources of food contamination
  • Meat products: During the cooking process of grilling, grilling, frying, and smoking, more PAH pollution comes from charcoal fire smoke and high-temperature cracking of fat;
  • Agricultural products: broad-leaf vegetables are susceptible to atmospheric pollution; cereals and oil seeds can be contaminated by smoke and exhaust gas;
  • Contamination during food processing: For example, oil on machinery and equipment contaminates food;
  • Sources of PAHs in human diet: Total dietary research results are: oils > grains > vegetables and fruits.

11. Disinfection of food utensils and cleaning of places

(1) Cleaning in place (CIP): CIP is the abbreviation of English Clean-In-Place, that is, cleaning in place or cleaning in situ. It means that equipment or components are not disassembled, and the equipment or components are not disassembled under sealed conditions. A method in which the temperature and concentration of the cleaning fluid exert a strong effect on the cleaning device to clean and sterilize the surfaces in contact with food.

(2) Other cleaning methods

1. Hot water washing: The main advantage of using hot water (60℃-80℃) for washing in fruit and vegetable processing plants is that it requires less investment in cleaning equipment.

2. High-pressure and low-flow cleaning: Because high-pressure spray cleaning can wash away heavy dirt, it is widely used in fruit and vegetable processing plants. High-temperature spraying can cause dirt to condense onto the surface to be cleaned, thereby promoting the growth of microorganisms, so the water temperature should not exceed 60°C.

 3. Foam cleaning: Foam cleaning can clean ceilings, walls, pipes, bolts, and storage containers simply and quickly, so it is widely used in fruit and vegetable processing plants.

4. Gel cleaning Because gel is adsorbent, it is a particularly effective medium in cleaning canning and packaging equipment.

5. Slurry cleaning: Since the slurry solution is more fluid than the foam, it is easier to penetrate into uneven surfaces, so the cleaning efficiency in the cannery is higher, but the adhesion of the slurry solution is worse than that of the foam.

6. Integrated high-pressure and foam cleaning combined. Because foam can clean large areas, high-pressure is suitable for cleaning various conveyor belts, stainless steel output equipment and hard-to-reach surfaces in canneries, so the system has great flexibility.

12. Dairy hygiene issues (see page 384 of "Nutrition and Food Hygiene")

Hygiene of milk production: The design of the dairy plant and the hygiene of the equipment should comply with the requirements of the hygiene standards of the dairy plant; milking should be carried out according to operating procedures; the milk must be purified to remove non-soluble insoluble matter such as grass clippings, cow hair, and milk lumps. Impurities; the purpose of sterilizing milk is to kill pathogenic bacteria and most reproductive microorganisms.

Hygienic storage and transportation of milk: Milk should be kept at low temperature during storage and transportation.

Milk spoilage: Lactin; milk is rich in nutrients. Microorganisms contaminated during the milking process can easily grow and reproduce, leading to spoilage.

Treatment of sick animal milk: Corresponding disinfection and sanitary treatment must be given, or it may be limited to food industry use, or discarded.

Antibiotic residues, pesticide residues, mycotoxins, etc. in milk exceed standards.

13. Person responsible for food safety

14. Foodborne diseases (see Chapter 11 of "Nutrition and Food Hygiene")

A type of disease with infectious and poisonous properties caused by various pathogenic factors that enter the human body through ingestion.

15. The main contents of HACCP (Note: For specific knowledge, see page 513 of "Nutrition and Food Hygiene" last semester)

(1) Conduct hazard analysis

(2) Determine critical control points (CCP)

(3) Set key limits for critical control points

(4) Establish a system to monitor and detect the control status of each key control point

(5) Establish corrective measures that should be taken when monitoring prompts that a key control point is out of control.

(6) Establish verification procedures to confirm the effective operation of the HACCP system.

(7) Establish documents and files of various procedures and records related to the above content and its application.

16. GFSI plan

1. In 2000, more than 50 retail giants and related associations in the world launched the "Global Food Safety Initiative-GFSI".
   1. GFSI certification was proposed by European international food retailers with the purpose of seeking continuous improvement of food safety systems and ensuring that consumers have safer food.
   2. GFSI certification does not establish new standards, but reviews existing food safety standards by establishing accreditation guidelines.
   3. Food safety certification standards that comply with GFSI accreditation guidelines can be recognized by GFSI and recognized by retailers. 
   4. Supports British Retail Council technical standards , Dutch HACCP specifications (audit standards) , etc.
   5. Developed ISO22000 with ISO
   6. Guidance documents:
      1. Food Safety Program Requirements.
      2. Qualified food standard management system: GAP, GMP, HACCP.
      3. Requirements for certification bodies.

17. All contents of risk analysis

1. Risk analysis :The entire process ofof various hazard elements, selecting and implementing appropriate controlpolicies and measures, and continuouslyadjusting and revising themtoreduce the risk of damage

Contents of risk analysis: 1. risk assessment risk assessment 

2. risk management risk management 

3. risk communication risk information exchange

18. Management of GRAS and ALARA substances.

1 ) .GRAS ( general regard as safety ) substances : substances that are generally regarded as safe

2) .ALARA ( As low as reasonably achievable ) substances : substances that should be avoided as much as possible

19. ISO22000, ISO14000, ISO9000 and food safety related content.

1. Some contents of ISO22000
   1. The organization must have a recall or product withdrawal procedure.
   2. The traceability system enables traceability from the direct supplier to the end of the manufacturing process, and from the final product to the direct supplier.
   3. Requirements must not be reduced when the product is unsafe or contains safety hazards.
   4. ISO22000 links the HACCP plan and prerequisite programs and determines the responsibilities of management, thus strengthening the role of HACCP.

20. Total Diet Study

Total Diet Study (TDS): It directly detects the content of various pollutants in all cooked(including drinking water) of residents to obtain the dietary intake of food contaminants for a population or subpopulation. This method is internationally recognized as the universal and best method for evaluating the dietary intake of chemical contaminants and nutrients among large-scale populations in a country or region. These data are of great significance for understanding food safety status, formulating food safety standards and food safety control measures.

21. Supervision model of food safety (unsure of the answer)

Multi-sector model: Japan, China, etc.

Single sector model: Germany etc.

Comprehensive mode: United States, Canada, Australia , etc.

22. Basic contents of food safety certification management (not sure about the answer)

1. China Certification and Accreditation Administration CNCA, Certification and Accreditation Administration of China .
2. The CNCA authorizes the national accreditation agency China National Accreditation Service for Conformity Assessment (CNAS) to be responsible for the accreditation of certification agencies, laboratories, inspection agencies and other related institutions.
   1. GMP: pharmaceutical companies, health food companies, and some general foods.
   2. HACCP—400 households
   3. ISO9000 quality management system certification. -10,000 homes
   4. ISO14000 environmental management system certification. -few
   5. ISO22000 food safety management system. -Zhejiang Zhoushan Luyuan Aquaculture Co., Ltd. passed the aquaculture ISO22000 certification of the Swiss  SGS Standard Certification Corporation (2008-5, the first).

23. CAC’s opinions on food safety legislation.

a. Emphasize that the law is based on science: application of risk analysis theory 

b. Emphasize the whole process management from farm to table

c. Emphasize the responsibility of food producers and operators to ensure food safety: Enterprises implement HACCP and strengthen self-management measures, such as voluntary product recalls. Social responsibility has become an important part of business management and entrepreneurship in developed countries.

d. The government reduces excessive legal restrictions (Deregulation)

e. Emphasis on coordination

Question type:

Multiple choice questions are worth 20 points, fill-in-the-blank questions are worth 20 points, term explanations are worth 40 points, and essay questions are worth 20 points.