三聚氰胺是什么?奶粉中为何会有三聚氰胺What is melamine? Why melamine powder in

本站新闻：三聚氰胺是什么?奶粉中为何会有三聚氰胺

管理员 投递于 2008-9-17 14:58:07

　　最近这个三聚氰胺比较出名，公子我是学高分子材料的，对这个三聚氰胺多少有些了解，近来不少人问我这个三聚氰胺是啥东西？那俺就给大家说说：

　　三聚氰胺（英文名Melamine），是一种三嗪类含氮杂环有机化合物，重要的氮杂环有机化工原料。简称三胺，又叫2 ,4 ,6- 三氨基-1,3,5-三嗪、1,3,5-三嗪-2,4,6-三胺、2,4,6-三氨基脲、蜜胺、三聚氰酰胺、氰脲三酰胺，分子式C3N6H6、C3N3(NH2)3，分子量126.12。

三聚氰胺物理化学特性

　　三聚氰胺性状为纯白色单斜棱晶体，无味，密度1.573g／cm3 (16℃)。常压熔点354℃（分解）；快速加热升华，升华温度300℃。溶于热水，微溶于冷水，极微溶于热乙醇，不溶于醚、苯和四氯化碳，可溶于甲醇、甲醛、乙酸、热乙二醇、甘油、吡啶等。低毒。在一般情况下较稳定，但在高温下可能会分解放出氰化物。

　　呈弱碱性（pKb=8），与盐酸、硫酸、硝酸、乙酸、草酸等都能形成三聚氰胺盐。在中性或微碱性情况下，与甲醛缩合而成各种羟甲基三聚氰胺，但在微酸性中（pH值5.5～6.5）与羟甲基的衍生物进行缩聚反应而生成树脂产物。遇强酸或强碱水溶液水解，胺基逐步被羟基取代，先生成三聚氰酸二酰胺，进一步水解生成三聚氰酸一酰胺，最后生成三聚氰酸。转自"碧云.轩"

三聚氰胺主要用途

　　三聚氰胺是一种用途广泛的基本有机化工中间产品，最主要的用途是作为生产三聚氰胺甲醛树脂（MF）的原料。三聚氰胺还可以作阻燃剂、减水剂、甲醛清洁剂等。该树脂硬度比脲醛树脂高，不易燃，耐水、耐热、耐老化、耐电弧、耐化学腐蚀、有良好的绝缘性能、光泽度和机械强度，广泛运用于木材、塑料、涂料、造纸、纺织、皮革、电气、医药等行业。

三聚氰胺生物学毒性

　　目前三聚氰胺被认为毒性轻微，大鼠口服的半数致死量大于3克/公斤体重。据1945年的一个实验报道：将大剂量的三聚氰胺饲喂给大鼠、兔和狗后没有观察到明显的中毒现象。动物长期摄入三聚氰胺会造成生殖、泌尿系统的损害，膀胱、肾部结石，并可进一步诱发膀胱癌。1994年国际化学品安全规划署和欧洲联盟委员会合编的《国际化学品安全手册》第三卷和国际化学品安全卡片也只说明：长期或反复大量摄入三聚氰胺可能对肾与膀胱产生影响，导致产生结石。然而，2007 年美国宠物食品污染事件的初步调查结果认为：掺杂了≤6.6%三聚氰胺的小麦蛋白粉是宠物食品导致中毒的原因，为上述毒性轻微的结论画上了问号。但为安全计，一般采用三聚氰胺制造的食具都会标明“不可放进微波炉使用”。

三聚氰胺的假蛋白原理

　　由于食品和饲料工业蛋白质含量测试方法的缺陷，三聚氰胺也常被不法商人用作食品添加剂，以提升食品检测中的蛋白质含量指标，因此三聚氰胺也被人称为“蛋白精”。

　　蛋白质主要由氨基酸组成，其含氮量一般不超过30%，而三聚氰胺的分子式含氮量为66％左右。通用的蛋白质测试方法“凯氏定氮法”是通过测出含氮量来估算蛋白质含量，因此，添加三聚氰胺会使得食品的蛋白质测试含量偏高，从而使劣质食品通过食品检验机构的测试。有人估算在植物蛋白粉和饲料中使测试蛋白质含量增加一个百分点，用三聚氰胺的花费只有真实蛋白原料的1/5。三聚氰胺作为一种白色结晶粉末，没有什么气味和味道，掺杂后不易被发现。

　　奶粉事件：各个品牌奶粉中蛋白质含量为15-20%（晚上在超市看到包装上还有标示为10-20%的），蛋白质中含氮量平均为16%。以某合格牛奶蛋白质含量为2.8%计算，含氮量为0.44%，某合格奶粉蛋白质含量为18%计算，含氮量为2.88%。而三聚氰胺含氮量为66.6%，是牛奶的151倍，是奶粉的23倍。每100g牛奶中添加0.1克三聚氰胺，就能提高0.4%蛋白质。大家现在明白奶粉中为什么会有三聚氰胺这东西了吧？

　　微溶系指溶质1g(ml)能在溶剂100～不到1000ml中溶解，三聚氰胺在水中微溶，在牛奶这种水包油型的乳液中溶解度未找到实验数据，本人觉得比水的溶解度要好一些，待验证。

三聚氰胺与肾结石

　　吃了含三聚氰胺为什么会得肾结石呢？三聚氰胺本身毒性轻微，据说动物长期摄入三聚氰胺会造成生殖、泌尿系统的损害，膀胱、肾部结石，并可进一步诱发膀胱癌。为什么吃了含三聚氰胺的奶粉会得肾结石呢？

　　公子我用百度研究了好久，终于找到2个专家的说法：

　　解放军第一医院泌尿科住院总医师李文辉则告诉记者，化验发现，收治婴儿中有90%以上为尿酸胺结石，这种情况在结石中非常少见，只占到各种结石的6%-10%。经过进一步检测，推测这些婴儿是由于摄入的脂肪和蛋白含量比例失调，引起体内嘌呤碱代谢异常，继而产生尿酸和尿酸盐结晶，在上尿路梗阻后形成肾结石，导致肾衰竭。“我个人认为，这些孩子肾结石与奶粉的关系很大，化验的事还要其他部门确认。”李文辉说。
　　南京大学医学院博士生导师、南京鼓楼医院泌尿科外科孙西钊教授告诉记者，这种结石的成分是由二水尿酸和尿酸铵混合形成的，具体形成的原因比较复杂。通过溶石的实验后，发现以二水尿酸为主。

　　公子我寻思着：原来这个三聚氰胺起到的不是直接的作用，是间接的？三聚氰胺冒充了蛋白，引起脂肪和蛋白含量比例失调，婴儿的主要蛋白来源是奶粉，奶粉脂肪和蛋白含量比例失调，就会引起肾结石？那成人吃含三聚氰胺的奶制品是不是就安全了？因为我们还有其他蛋白来源。天，搞不懂，俺不是学医的，就跟你们解释到这里。公子我还常喝酸奶啊，安全吗？

Site News: What is melamine? Why melamine powder in

Recently, the well-known melamine, I am a son of polymer materials science, this melamine somewhat understand that many people have recently asked me what this thing is melamine? Anjiu to talk about it all:

Melamine (English name Melamine), a triazine heterocyclic organic compounds, it is important to ring nitrogen organic chemical raw materials. Three referred to as amines, also known as 2, 4, 6 - three amino-1 ,3,5 - triazine, 1,3,5 - triazine-2 - three-, 2, 4, 6 - three amino Urea, melamine, the three-cyanide-, three-urea cyanide, molecular formula C3N6H6, C3N3 (NH2) 3, molecular weight 126.12.

Melamine physical and chemical properties

Melamine characters for the pure white monoclinic crystal edge, tasteless, density 1.573g/cm3 (16 ℃). Normal melting point 354 ℃ (decomposition); rapid increase dye-sublimation, distillation temperature 300 ℃. Soluble in hot water, micro-soluble in cold water, very little heat soluble in ethanol, insoluble in ether, benzene and carbon tetrachloride can be dissolved in methanol, formaldehyde, acetic acid, hot ethylene glycol, glycerin, pyridine, and so on. Low toxicity. Under normal circumstances, a more stable, but at a high temperature may break down to release cyanide.

Was weak alkaline (pKb = 8), and hydrochloric acid, sulfuric acid, nitric acid, acetic acid, oxalic acid, and so be able to form a melamine salt. In the neutral or slightly alkaline, the condensation of formaldehyde and from a variety of hydroxymethyl melamine, but in the middle of Micro (pH value of 5.5 to 6.5) and hydroxymethyl derivatives for the condensation reaction and generate a product of resin. Case of strong acid or alkali solution hydrolysis, the amino-being gradually replaced by Mr. Cyanuric into the second-, third-generation further hydrolysis one-cyanate, the last generation Cyanuric. Carried over "Pik. Xuan"

Melamine is mainly used

Melamine is a wide range of basic organic chemical intermediates, the main purpose is the production of melamine formaldehyde resin (MF) of raw materials. Melamine can make a flame retardant, water-reducing agent, formaldehyde cleaning agents. The hardness of resin than urea-formaldehyde resin, non-flammable, water-resistant, heat-resistant, anti-aging, arc resistance, chemical corrosion resistance, good insulation properties, gloss and mechanical strength, widely used in wood, plastic, paint, paper, Textile, leather, electrical and pharmaceutical industries.

Melamine biological toxicity

Melamine is currently seen as slightly toxic, rat's oral LD50 is greater than 3 g / kg body weight. According to a 1945 experiment: the high dose of melamine fed to rats, rabbits and dogs did not observe significant toxicity. Animals can cause long-term intake of melamine reproductive, urinary system damage, bladder, kidney stones and may further induce bladder cancer. In 1994 the International Program on Chemical Safety and the European Commission co-editor of "International Chemical Safety Handbook," Volume III and the International Chemical Safety Cards only: the long-term or repeated intake of a large number of melamine may have an impact on kidney and bladder, Have led to the stone. However, the 2007 U.S. pet food contamination is a preliminary investigation concluded that: a mix of ≤ 6.6% of melamine in wheat gluten meal is the pet food poisoning led to the reasons for the above-mentioned slightly toxic to the conclusion drawn on the question mark. But the safe side, generally made of melamine utensils will be marked "can not be put into the use of microwave ovens."

Melamine leave the principle of protein

As the food and feed industry test the protein content of the defect, melamine unscrupulous traders also often used as a food additive to enhance the detection of food protein content indicators, the melamine was also known as the "sperm protein."

The main protein from amino acid composition, its nitrogen content less than 30%, and the formula of melamine nitrogen content of 66%. General protein test, "Kjeldahl" measured by nitrogen content to estimate the protein content, add melamine will make the food protein content of the test on the high side, so that the poor quality of food through the food inspection agency of the test. It was estimated in the vegetable protein powder and protein content of feed, make the test by one percentage point increase in the use of melamine, only the true cost of raw materials protein 1 / 5. Melamine is a white crystalline powder, no smell and taste, not after doping was found.

Milk powder incident: the various brands of milk protein content of 15-20% (in the supermarket that night package also marked as 10-20%), protein nitrogen content in an average of 16%. To pass a milk protein content of 2.8% to 0.44% nitrogen content, a qualified milk protein content of 18% to 2.88% nitrogen content. Melamine and 66.6 percent for the nitrogen content is 151 times that of milk, milk powder is 23 times. Add milk 100g per 0.1 grams of melamine, will be able to raise the 0.4 percent protein. Now you understand why there melamine powder in this thing now?

Micro-dissolved solute means 1g (ml) in the solvent from 100 to less than 1000ml dissolved, melamine micro-soluble in water, milk in this oil-in-water emulsion of the type found in the solubility of experimental data, I feel better than the water solubility , To be verified.

Melamine and kidney stones

Why eating melamine-containing kidney stones will have to do? Melamine is slightly toxic, long-term intake of animal is said to cause reproductive melamine, urinary system damage, bladder, kidney stones and may further induce bladder cancer. Why eating melamine-containing kidney stones of the formula will have to do?

I use Baidu's son studied for a long time, finally found 2 experts:

The first People's Liberation Army General Hospital urologist Dr. Li Wenhui hospital told reporters that laboratory tests found that babies treated in more than 90% for stone-uric acid, which is very rare in stone, only to a variety of stones 6% -10 %. After further testing, they speculated that the baby was due to the intake of fat and protein content ratio imbalance in the body caused by abnormal metabolism of purine base and then produce uric acid and salt crystallization in the upper urinary tract obstruction after the formation of kidney stones, leading to kidney failure. "My personal view is that the children's milk with kidney stones in it to do tests also confirmed that other departments." Li Wenhui said.
Nanjing University School of Medicine doctoral tutor, Nanjing Gulou Hospital Surgical Urology Professor Sun Xizhao told reporters that the composition of stone from dihydrate uric acid in urine and the formation of the mixed perchlorate, a specific form of a number of complicated factors. Litholytic through the experiment, found mainly in acid dihydrate.

I have a son thinking: So this is not the melamine played a direct role in indirect? Melamine posing as a protein, fat and protein content caused by imbalance, the baby's milk is the main source of protein, fat and protein content of milk powder imbalance, it will cause kidney stones? That adults eat dairy products containing the melamine is not on the security? Because we have other sources of protein. Days, do not understand, the span is not a medical student, you like to explain here. He Suannai my son often ah, safe?