You know how much melamine Source: Science and Technology Daily Category: Technical Articles Update Time: 2008-10-8 16:37:21 Read 70 times Tang Ting Yuan Zhiyong roundup
"Melamine" has a seemingly fabulous alias "Protein," which has appeared in online advertisements with trepidation. It has openly advertised that it "can increase the protein content of products." In the "Stone Gate" incident, this small white crystal "demonstrated itself" and defeated many "smart people". Then, what is the "protein essence" that the dairy company CEOs "won't know" is?
Its characteristics
Melamine is pure white monoclinic crystal, odorless, soluble in hot water, slightly soluble in cold water. Low toxicity, weak alkaline (pH=8). The main application is as raw material for the production of melamine formaldehyde resin (MF), which has high hardness, non-flammability, water resistance, heat resistance, aging resistance, arc resistance, chemical resistance, good insulation properties, gloss and mechanical properties. Strength, widely used in wood, plastics, coatings, paper, textiles, leather, electrical, pharmaceutical and other industries.
Its toxicity
Long-term ingestion of melamine in animals can cause damage to the reproductive and urinary systems, and stones in the bladder and kidneys can further induce bladder cancer. Volume III of the International Chemical Safety Handbook and the International Chemical Safety Card, edited by the International Chemical Safety Programme and the European Union Commission in 1994: long-term or repeated heavy ingestion of melamine may have an effect on the kidneys and bladder, resulting in stone. A preliminary survey of pet food contamination incidents in the United States in 2007 concluded that wheat protein meal spiked with ≤ 6.6% melamine was the cause of poisoning in pet foods.
Experts' risk assessment of contaminated infant formula milk powder showed that for infants weighing 7 kg, assuming a daily intake of 150 grams of milk powder, the safe pre-set value is a maximum tolerable dose of 15 mg/kg milk powder.
According to the US Food and Drug Administration, the daily tolerable intake of melamine is 0.63 mg/kg body weight. In other words, a tolerable intake of 37.8 mg per day for a 60 kg adult and 2563 mg/kg for Sanlu.
Its harm
When melamine is added to milk, another chemical, cyanuric acid, is produced during the production process. Melamine and cyanuric acid combine to form a network of crystals. This crystal is slightly soluble in water and will dissolve when it is eaten in the human body, but it will be discharged into the urine and the two substances will recombine. Because the urinating tubules are very fine, these network-like crystals may block the kidneys. Small tubes, with the increase in the content of crystals in the body, if it can not be ruled out, accumulated to a certain extent after the formation of stones, kidney function has caused great damage.
Infants and young children's renal tubules are much thinner than adults and are more likely to cause blockages. The infants' staple foods are milk powder and they consume a lot of them. Plus, some parents don’t pay attention to giving children plenty of water and harmful substances that accumulate in the body. Many, in addition, infants and young children can not accurately express their own feelings, so infants and young children are more likely to stone.
Pseudoprotein
Proteins are mainly composed of amino acids, nitrogen content generally does not exceed 30%, while melamine's formula nitrogen content reaches 66%. Due to the high cost of protein quantification, most dairy companies in China use the Kjeldahl method to measure nitrogen content to estimate protein content. Therefore, adding melamine will make the protein test content of foods high, and it acts as a White crystalline powder, odorless, not easily found after doping.
With a certain amount of protein content of qualified milk powder of 18%, the nitrogen content was 2.88%. The melamine nitrogen content is 66%%, which is 23 times that of milk powder, and the price is much lower than that of real protein raw materials. This is really a profit.
Its detection
The melamine detection method of the US Food and Drug Administration (FDA) and the melamine detection method announced by the Chinese Ministry of Agriculture use the Agela ASB series hydrophilic chromatography column, which can achieve good results.
According to industry insiders, major dairy products companies in the country are mainly tested by liquid chromatographs, and the Sanlu Plant's laboratory also has this instrument.
The price of this liquid chromatograph is between RMB 400,000 and RMB 800,000. Recently, Chongqing City purchased a liquid chromatograph worth 680,000 yuan, and conducted a large-scale melamine test on the city's dairy products.
It is understood that although the Sanlu General Plant has this equipment, the majority of branch companies that collect local milk and produce locally do not have this equipment, and the plant's equipment is "sleeping" most of the time.
——— Related Questions and Answers--
Q: What should I do if I find out that my child has consumed melamine-containing milk powder?
A: When you learn that infants and young children have eaten melamine milk, immediately stop drinking the milk powder and replace it with other qualified brands of milk powder. Observe whether children have various symptoms of poisoning. It is best to take the child to the hospital urology department for urine routine and urinary tract ultrasound examinations, and to discover or rule out the possibility of kidney stone disease. Once a stone is found, it must be diagnosed by a specialist doctor to diagnose the extent of kidney function and take effective treatment. After active treatment, the removal of toxic substances in the body will not affect the growth and development of children, nor will it bring sequelae to the health of children.
Suspected baby with kidney stones must give them plenty of water, so that on the one hand it can dilute the content of toxic substances in the body, promote its faster excretion, and on the other hand, it also contributes to the discharge of kidney stones. It is consistent with the treatment of adult kidney stones.
Q: What foods and utensils may also contain melamine?
A: Without professional testing, it cannot be asserted that certain dairy products will contain melamine. However, melamine can be found in foods made from powdered milk, such as charcoal coffee, milk tea, green matcha tea, papaya milk, pudding powder, and ice cream powder. Pure fresh dairy products do not contain melamine if they have not been mixed with water, or if they are not made from milk powder blending.
In addition, some eating utensils are also made from melamine. These utensils are relatively safe, but they decompose toxic substances in the high-temperature heating of microwave ovens.
Q: Is there any way to make up for the Kjeldahl deficiency?
A: Just one more step is needed: First try treating the sample with trichloroacetic acid. Trichloroacetic acid allows the protein to form a precipitate. After filtration, the nitrogen content of the precipitate and the filtrate is determined, and the true content of the protein and the nitrogen content of the impersonated protein are known. This is a common knowledge of biochemistry and has long been an international standard for the detection of nitrogen in milk (ISO 8968).
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