First, the difference between edible salt and industrial salt
(1) Structural difference: edible salt is relatively pure sodium chloride; Besides sodium chloride, industrial salt also contains sodium nitrite.
(2) Differences in properties: the properties of edible salt are relatively stable, and the aqueous solution is neutral; Sodium nitrite contained in industrial salt is relatively stable under dry conditions, but it can be slowly oxidized into sodium nitrate by oxygen absorption, and the aqueous solution is alkaline.
(3) Appearance difference: Edible salt contains iodine, which is white and fine sand with little water. When pinched by hand, there will be no feeling of condensation, and it may be yellow or light blue under special circumstances; Industrial salt does not contain iodine, its color is gloomy, its shape is mostly granular, and its water content is high. Sodium nitrite may be slightly yellowish.
(4) Taste difference: Edible salt is salty; Sodium nitrite is slightly salty, so it is difficult to tell by taste when eating it.
Second, the harm of edible industrial salt
Industrial salt contains a lot of nitrite. Common industrial salt poisoning incidents are mostly caused by eating sodium nitrite by mistake or eating too much. Sodium nitrite is mainly used in dyes, medicine, printing and dyeing, bleaching and so on. Because of its coloring, antibacterial and antiseptic effects, it is often used as a coloring additive for cooked meat products in food industry. China's Hygienic Standard for the Use of Food Additives stipulates that the maximum dosage of sodium nitrite in meat is 0. 1.5g/kg, and its residue in meat products shall not exceed 0.03g/kg；. It shall not exceed 0.05g/kg in canned meat products. Generally speaking, as long as the human body ingests 0.2 ~ 0.5 grams of nitrite, it will cause poisoning; Ingestion of 3 grams of nitrite will lead to death.
Third, the symptoms of industrial salt poisoning
Replacing edible salt with industrial salt can easily lead to food poisoning. The main causes of common industrial salt poisoning incidents are: using "industrial salt" containing nitrite as edible salt; Mistaken nitrite as edible salt; Eating pickled meat products, pickles and spoiled vegetables with high nitrate and nitrite content; Drinking bitter well water and boiler water with high nitrate or nitrite content; Excessive use of nitrite in meat processing.
Nitrite is a strong oxidant, which combines with hemoglobin after entering the blood, turning oxygenated hemoglobin into methemoglobin, thus losing its oxygen-carrying ability, leading to tissue hypoxia, cyanosis and poisoning. In addition, nitrite can dilate peripheral blood vessels. After excessive intake of nitrite poisoning, the onset is rapid, and the general incubation period is 1 ~ 3 hours, which leads to paralysis of vascular motor center, respiratory center and peripheral blood vessels and the formation of methemoglobin. Acute poisoning is characterized by general weakness, headache, dizziness, nausea, vomiting, diarrhea, chest tightness, dyspnea, and obvious cyanosis of skin and mucosa. In severe cases, blood pressure drops, leading to coma and even death.
Fourth, preventive measures.
(1) When buying edible salt, you should choose a regular merchant to buy it. Pay attention to the sensory quality and packaging label of edible salt. You should choose salt with white appearance and spun yarn shape. The label should clearly and completely record the ingredients, content, factory name, address and other information, and at the same time ask for the purchase certificate.
(two) to raise awareness of toxic substances, it is forbidden to use industrial salt instead of edible salt, and it is forbidden to mix the two. Containers for packaging or storing nitrite should have eye-catching signs.
(3) Excessive use of nitrite in meat processing is prohibited. Don't eat rotten vegetables or pickled vegetables. Don't drink bitter well water, don't cook and mix noodles with bitter well water.