General principles for handling contaminated food

作者：admin  点击次数：23  发布时间：2025-03-29

For contaminated food, the general treatment principle can be mastered, that is, separate the uncontaminated and contaminated food, the uncontaminated part can be eaten, and the contaminated part can be handled separately according to the situation.
Treatment of contaminated food: Different treatments should be made according to different situations such as the type, source, toxicity, mode, degree and scope of contamination, type and quantity of contaminated food. The treatment principle is to minimize losses as much as possible on the basis of ensuring the safety of the consumer. Available treatment methods include removing the contaminated part, using special physical and chemical or food processing methods to destroy or remove contaminants, restricting temporary consumption, diluting, changing to other uses, and destroying.
Section 2 Biological contamination of food and its prevention
Food microbial contamination refers to the contamination of food by microorganisms and their toxins during processing, transportation, storage, and sales. On the one hand, food microbial contamination reduces the sanitary quality of food, and on the other hand, it can cause varying degrees of harm to the consumer himself. Microorganisms that contaminate food can be divided into three categories according to their pathogenicity to humans:
① Direct pathogenic microorganisms, including pathogenic bacteria, pathogenic bacteria and viruses of zoonotic infectious diseases, toxin-producing molds and mycotoxins, which can directly cause human disease and cause harm; ②) Relatively pathogenic microorganisms, that is, microorganisms that are not pathogenic under normal conditions but have pathogenicity under certain special conditions: ③ Non-pathogenic microorganisms, including non-pathogenic bacteria, non-toxic molds and common yeasts, which are harmless to the human body and are the main cause of food spoilage and sanitary quality decline.
1. Bacterial contamination of food
The bacteria present in food are only a small part of those in nature. Generally, these common bacteria in food are called food bacteria, including pathogenic, relatively pathogenic and non-pathogenic bacteria. Here we focus on non-pathogenic bacteria, which are important indicators for evaluating the hygienic quality of food. They are often related to the appearance of specific colors, odors, fluorescence, phosphorescence and relative pathogenicity of food, and they are also the main objects for studying the causes, processes and control methods of food spoilage.
(-) Common food bacteria
1. Pseudomonas
Pseudomonas is a representative of food spoilage bacteria. It is a Gram-negative, non-spore-bearing bacillus that is aerobic, psychrophilic, or halophilic. It is widely distributed in food, especially vegetables, meat, poultry and seafood. It is an important bacterium that causes fresh frozen food to spoil.
2. Micrococcus and Staphylococcus are both Gram-positive, catalase-positive cocci that are mesophilic. The former is aerobic and the latter is anaerobic. They have become very common bacteria in food because of their low nutritional requirements. They can decompose sugars in food and produce pigments.
3. Bacillus and Clostridium
They are Gram-positive bacteria. The former is aerobic or facultatively anaerobic, and the latter is anaerobic. They are both mesophilic and thermophilic. They are widely distributed in nature and are common spoilage bacteria in meat products.
4. Enterobacter
Except Shigella and Salmonella, all Enterobacteriaceae are common food spoilage bacteria. They are Gram-negative, non-spore-forming bacilli, aerobic or facultative anaerobic, mesophilic bacilli, and are often associated with the spoilage of aquatic products, meat, and eggs. Among them, Proteus has a very strong ability to decompose protein and is a representative of aerobic spoilage bacteria; while Serratia can cause changes such as reddening and stickiness on the surface of food.
5. Vibrio and Flavobacterium
Both are Gram-negative straight or curved rods, facultative anaerobic, mainly from seawater or freshwater, and can grow at low temperatures and 5% salt, so they are common in fish and aquatic products. The latter is related to the spoilage of frozen meat products and frozen vegetables, and is known for its ability to use sugars in plants to produce yellow and red pigments.
6. Halobacterium and Halococcus
Both are gram-negative aerobic bacteria that love salt and grow in high concentrations of salt (at least 12%). They are often found in extremely salty fish and can produce orange-red pigments.
7. Lactobacillus
Often appearing together with lactic acid bacteria, gram-positive, catalase-negative rods, anaerobic or micro-absorbent, mainly found in dairy products, which can cause them to spoil.