Common Sense When Purchasing Canned Fish

The so-called canned food refers to food that is packaged in sealed containers, has been moderately heat sterilized (to achieve commercial sterility), and can be stored for a long time at room temperature. Canned food is a traditional food with various packaging forms and varieties. It is easy to eat and carry. It is extremely convenient and important for dietary supplements for mobile workers such as traveling, field operations, national defense, industry and mining, and exploration. But if you choose incorrectly, it will harm your health. Here are some common spoiled cans to help you identify them.
(1) Rust The rust of cans can be divided into external rust and internal rust. There are many reasons for corrosion, such as incomplete welding, cracks, edges, dents and perforations, etc., causing juice to overflow and the tank body to be unclean and rusty; the packaging skin has exposed iron, or the solder has fallen off, causing rusty spots or vulcanization on the tank. There are iron spots, small pieces of solder or internal flow of glue in the tank, and the heavy metal content is often high. Whether it is external rust or internal rust, once the can wall is perforated, its contents will be contaminated by bacteria, and the heavy metal content of the food in the can will exceed the standard, so it cannot be purchased.
(2) Fat listening means drum listening. When the pressure inside the can is greater than the air pressure, the two bottom ends of the can expand and bulge, a phenomenon called fat tinting. Obesity can be divided into biological obesity, chemical obesity and physical obesity.
Biological fat cans are caused by incomplete sterilization of cans during the production process or bacteria re-entering the cans to decompose food and produce carbonic acid gas, causing fat cans. This kind of fat listening is called corrupt fat listening, also called true fat listening. Biological fat can often contain unpleasant acidic putrefactive gas after opening, which is harmful to the human body and cannot be eaten.
Chemical fat tinting is caused by the food in the can being highly acidic, and the inner layer of tinplate being coated with tin unevenly, or the tin layer being damaged. The organic acid in the food interacts with the iron for a long time, causing a chemical reaction, releasing hydrogen gas that accumulates in the can, and the pressure is too high. The big formation fat listens. This kind of obesity often occurs in canned fruits with higher acidity. After fat listening, the contents will change color easily and the heavy metal content is also high, so it is not suitable to buy.
Physical fatness is mainly caused by excessive content, insufficient exhaust, frozen cans or improper operation. Physical fattening is generally called fake fattening. The food in the can has not deteriorated and is edible.
(3) Discoloration, turbidity, and sedimentation of food in the tank. This kind of phenomenon mainly exists in food in glass cans. There are many reasons for this. For example, the glass cans are discolored due to direct sunlight during the operation process; some are caused by excessive temperature during storage, which promotes the decomposition of fat and sugar in the cans. Transformation, thus making the juice in the food turbid and darkened in color. Some of the reasons are due to excessive vibration during transportation, loading and unloading, and the contents are broken due to shock, etc. Cans with this phenomenon should not be purchased for consumption.
(4) Spoilage and rancidity: After this kind of canned food goes rancid, it does not produce fat and tincture, and its appearance is normal. It is mainly caused by the decomposition of contents by anaerobic bacteria such as Clostridium botulinum. This type of can can smell rancid and sour after opening its lid and must not be eaten. Because poisoning caused by botulinum toxin not only has severe symptoms, but also causes a high mortality rate, you must not be careless.
In view of the above, we must not take it lightly when choosing canned foods.
1. First, look at the product label. The label should be complete and clean, and can describe the food inside the can. For example, the main raw materials and auxiliary materials of the product, net content, consumption method, storage conditions, product standard number, etc.; the can lid is hard-printed with the factory code, factory name code, production date, product code, etc. If the trademark information is incomplete and shoddy, it is a substandard product. When choosing a production date, it's best to choose a recent product.
2. Observe the can body. For tinplate cans, if the surface of the can is clean and free of rust, the bottom and lid of the can are slightly recessed, the seams and bottom curls are not damaged, there are no iron tongues, and the seal is tight and stable, it is generally a good can. For glass cans, you must first observe whether the contents are turbid, precipitated, or discolored. A good can should have a normal color (the true color of the food), a complete block shape, clear soup, no sediment on the bottom of the can, and a slightly recessed lid. The iron cover and rubber ring are rust-free.
3. Listen to the sound and tap the center of the bottom cover with your finger. If the sound is crisp and solid, it indicates that it is a good can; if the sound is turbid and hollow, it indicates that the content is insufficient and there is more gas; if the sound is a hoarse "breaking" sound, it indicates that the can has been Go bad.
4. When opening the can, pay attention to whether the color, flavor, and shape of the food in the can are normal. If it is found to be moldy, smelly, lumpy, or porridge-like, it means the food has spoiled and is not suitable for consumption.