At present, the main fresh-keeping products on the market are chicken essence and monosodium glutamate.
The main component of monosodium glutamate is sodium glutamate (MSG). It is made of carbohydrates (starch, molasses, etc.). ) by microbial fermentation, and then refined or hydrolyzed by protein. The production of monosodium glutamate in China is mainly concentrated in Shandong, Henan, Zhejiang, Jiangsu and Guangdong provinces, accounting for about 85% of the total national output.
There are mainly two kinds of monosodium glutamate in the market, namely powdered monosodium glutamate with 80% sodium glutamate content and crystalline monosodium glutamate with more than 99% sodium glutamate content. But no matter what kind of monosodium glutamate, the ingredient that ultimately reflects the umami taste is the sodium glutamate contained in it. Because the salt content of powdered monosodium glutamate containing 80% sodium glutamate is above 10%, it is salty when used, and its freshness is worse than that of monosodium glutamate containing 99% sodium glutamate. From this point of view, 99% monosodium glutamate is naturally better than 80% monosodium glutamate.
Sodium glutamate exists in the form of glutamic acid after dissolution. Glutamate is one of the amino acids needed by human body. In human brain tissue, it can be converted into δ-aminobutyric acid under the catalysis of glutamate decarboxylase, and δ-aminobutyric acid is an inhibitory neurotransmitter, so glutamate is beneficial to maintain the function of nervous system. But the human body can synthesize glutamic acid by itself, so you can't eat too much glutamic acid. If you take too much, it will cause the imbalance of glutamic acid in the human body, which will cause numbness in the upper limbs, asthma in the heartbeat and dizziness. According to the World Health Organization, the daily intake of monosodium glutamate for adults should not exceed 1.20 mg per kg body weight, which means that an adult weighing 50 kg can only eat 6 grams of 99% monosodium glutamate per day at most.
The umami components of chicken essence include sodium glutamate, sodium nucleotide (IMP, GMP), tryptophan in chicken bone meal or concentrated extract, radon acid in Tianmen, purine nucleotide, etc. Compared with the single umami flavor of monosodium glutamate, the umami flavor of chicken essence is softer, the taste is more round and full, and the flavor is rich. Chicken essence is rich in ingredients, and various composite raw materials bring protein, amino acids, vitamins, minerals and other nutrients to chicken essence, so chicken essence is a nutritional freshener.
Chicken essence is fresher than monosodium glutamate. The intensity of umami is called freshness. The principle of freshness enhancement of chicken essence lies in the "multiplication effect" of umami produced by the compatibility of sodium glutamate and disodium nucleotide. Taking sodium glutamate (99% monosodium glutamate) as the reference standard, the freshness of chicken essence can be determined by the contents of sodium glutamate and disodium nucleotide.
After decades of research, scientists have found that the "multiplication effect" of umami flavor of glutamic acid and flavor nucleotide disodium has certain rules. The freshness of sodium glutamate is 1. When sodium glutamate is mixed with 5 '- inosinic acid, its freshness multiple is y = u+ 1200 UV (formula 1). When sodium glutamate is mixed with 5 '- inosinic acid, it is VIMP+VGMP (formula 2), where u is glutamic acid. If the contents of sodium glutamate and sodium 5'- inosine in chicken essence are 35% and 0.4% respectively, the freshness of chicken essence is 1.68 times that of monosodium glutamate. At present, the freshness of chicken essence in the market is equivalent to 1.2 ~ 1.8 times that of monosodium glutamate.
In practical use, any condiment should follow certain scientific principles according to its characteristics, otherwise it will not only fail to achieve the ideal seasoning effect, but also have some negative effects, including monosodium glutamate and chicken essence.
The following points should be paid attention to in the cooking process of monosodium glutamate: 1? You shouldn't add it in the oil pan, you should add it before the dish is ready. This is because when the temperature is higher than 120℃, sodium glutamate will become the focus, which is harmful to human body after eating and difficult to excrete. If it accumulates in the body for a long time, it will cause reactions such as accelerated heartbeat, shaking hands and insomnia. 2? It is not advisable to add monosodium glutamate to acidic foods, such as sweet and sour fish and sweet and sour ribs. Monosodium glutamate is alkaline, and adding it to acidic food will cause chemical reaction and make dishes taste bad. 3? Not suitable for adding to alkaline food. For example, when making steamed bread, sodium glutamate will become disodium glutamate in alkaline environment, which will reduce the umami taste or even lose it. 4? Pay attention to the salty taste. Too salty, monosodium glutamate is not necessarily delicious; If it is too weak, the umami flavor of monosodium glutamate will not "hang". According to the research, when the ratio of monosodium glutamate to salt is in the range of 1: 3 ~ 1: 4, the taste can be mellow and soft. 5? When mixing cold dishes, dissolve them before adding them. Because the dissolution temperature of monosodium glutamate is 85℃, it is difficult to decompose monosodium glutamate below this temperature.
Chicken essence is much looser than monosodium glutamate in the cooking process. Chicken essence can be used in any situation where monosodium glutamate is used, and it can achieve good results when added to vegetables, soups and pasta, especially when added to soups and hot pots. Its aroma and taste take care of each other and complement each other, which can greatly increase appetite. But when using chicken essence, you should also pay attention to: 1? Because chicken essence itself contains about 10% salt, it should be used with less salt. 2? Because chicken essence contains nucleotides, and the metabolite of nucleotides is uric acid, gout patients should use it less. 3? The solubility of chicken essence is worse than monosodium glutamate. If it is not used in soup, it should be dissolved before use. Only dissolved substances can be perceived by taste cells. 4? Chicken essence contains salt and has strong hygroscopicity, so it should be sealed after use, otherwise the nutritious chicken essence will breed a large number of microorganisms and pollute food.
At present, the annual output of chicken essence in China is about 50,000 tons and monosodium glutamate is about 800,000 tons, and the market share of chicken essence in the whole condiment market is less than 10%. But in foreign countries, chicken essence has reached 60%. Because chicken essence is fresher and more nutritious than monosodium glutamate, chicken essence is now more and more popular with consumers. Since 1999, the annual consumption of chicken essence in China has increased by 30-40%. In the next 5- 10 years, the output of chicken essence in China is expected to reach 300,000-400,000 tons. By then, chicken essence will not only enter many restaurants, but also enter thousands of households.
What is monosodium glutamate?
For hundreds of years, some women in China and Japan have been using some kind of seaweed to make condiments, which are added in cooking to make food rich in flavor.
1908 Dr. Ikeda Miaoju, a professor at the University of Tokyo, found that glutamic acid contained in seaweed is the secret to make food rich in flavor. He pumped out the chemicals and formed crystals.
Japanese businessmen immediately made money from this discovery. The next year, monosodium glutamate was sold in the market. Those chemicals were extracted from wheat.
Today, about 20 countries in the world produce monosodium glutamate with an annual output of 400,000 tons.
The chemical name of monosodium glutamate is monosodium L- glutamate (MSG for short), which is a kind of glutamate. Many natural foods contain glutamate, such as tomatoes, cheese, mushrooms, millet and green beans. Most foods contain 1%-35% protein, of which 10-35% is glutamic acid. Glutamate is also continuously produced by human body, which is an indispensable ingredient in the manufacture of protein, and it is very important to help metabolism in the body. There is no difference between monosodium glutamate and glutamic acid produced by the human body itself. After digestion, it enters the normal biochemical pathway in the body to produce energy.
At present, the monosodium glutamate sold in the market is white crystalline particles with no peculiar smell. The most popular brand is "essence", but there are also products from local and other Southeast Asian countries sold in Hong Kong under other brands with similar ingredients. Almost all these monosodium glutamate are extracted from sugarcane syrup and cassava starch through complex fermentation process.
What is monosodium glutamate syndrome?
1968, a doctor named Guo Haowen ate in a China restaurant in new york. He felt paralyzed, starting from the back of his neck and extending to his arms, back and buttocks. At the same time, his whole body was weak and his heart beat faster. These symptoms lasted for two hours.
Dr. Guo found that many of his friends had similar symptoms after eating Chinese food, so he wrote to an American medical magazine to mention it.
After his letter was published, many people wrote that they had similar experiences. Some people think that these symptoms may be caused by monosodium glutamate used in restaurants in China. These symptoms are called "China restaurant syndrome". Many doctors and scientists have done experiments and found that some people who eat food containing monosodium glutamate will get restaurant disease in China.
Since then, "China restaurant syndrome" has frightened some westerners. However, the use of monosodium glutamate is the most common in eastern societies (Japan, South Korea, China, Malaysia, Thailand, etc.). ), and the west seldom eats, so it has never become a serious health problem. Strange to say, it seems that there are fewer adverse reactions to monosodium glutamate in the East.
Some people are sensitive to monosodium glutamate, for example, some asthma patients get worse after eating monosodium glutamate. After eating Chinese food, they first developed various symptoms of "China restaurant syndrome", and then they had asthma attacks after 12 to 14 hours. Some patients have to be sent to hospital for treatment because of their serious illness. If they are not taken care of in time, they may die. This condition is called "China restaurant asthma".
1973, the world health organization formulated a recommended maximum daily intake for individuals, which is applicable to infants and adults over 12 weeks old (newborn babies should never take any food additives): 120 mg of glutamic acid per kilogram of body weight, equivalent to/kg of sodium glutamate (monosodium glutamate) 135 mg.
A teaspoon of monosodium glutamate is of course a large amount, and few people will eat the whole teaspoon of monosodium glutamate into their stomachs. But "you can" eat 6 grams a day, which is actually equivalent to eating only 0.25 grams an hour on average. On weekdays, when we eat in restaurants, we often eat two or three grams of monosodium glutamate within an hour. Australian doctors have treated some asthma patients, and this is how acute diseases are sent to hospitals.
Some people who eat 1.5g monosodium glutamate (equivalent to a bowl of instant noodles or half a plate of fried rice or two or three plates of snacks) may cause "China restaurant syndrome" and "China restaurant asthma".
What are the symptoms of monosodium glutamate?
happen
Eating on an empty stomach is more common.
It took more than 2 grams to appear.
Women appear more.
After eating monosodium glutamate 15 minutes, it will disappear after one or two hours.
symptom
Facial congestion: burning sensation or burning sensation, swelling of tongue base.
Tension: abnormal or accelerated heartbeat, dizziness, headache, migraine, stiff neck, muscle contraction, nausea, insomnia and gastrointestinal discomfort.
Tingling: neck pain, arm pain, chest pain.
Numbness: upper limb aches and depression.
Allergy: Asthma and cough are aggravated.
Is monosodium glutamate safe?
Is monosodium glutamate harmful to human body? Is monosodium glutamate safe as seasoning? This is the question that citizens are most concerned about, and it is also a question that they want to know the answer for peace of mind.
The answer should be: I don't know at present.
"Harmful" and "safe" are not simple, black and white things.
"Eating too much will kill people", even fresh water can be fatal if poured into the stomach in large quantities. Eating too much sugar, salt and oil is also harmful to your health. In fact, most Hong Kong people do eat too much sugar, salt and oil, which leads to various serious diseases, such as high blood pressure and heart disease. In short, eating too much food is harmful and unsafe.
The problem of monosodium glutamate is particularly complicated because it is a very "natural" substance.
The manufacturer of monosodium glutamate pointed out the following facts, which proved that monosodium glutamate could not be harmful to human body:
Monosodium glutamate (monosodium glutamate) is a natural ingredient in food. Almost all foods containing protein (including human milk) contain monosodium glutamate.
Glutamate is constantly produced in human body, and its composition is exactly the same as monosodium glutamate.
The monosodium glutamate used for cooking on weekdays is less than what is already in the body and absorbed from other foods.
However, things are not divorced from reality. There are indeed many people who have long-term problems after eating food containing monosodium glutamate. Apart from psychological effects, one explanation is that some people are sensitive to the sudden increase of monosodium glutamate. Anyone who eats a meal containing a lot of monosodium glutamate will feel uncomfortable and have the so-called "monosodium glutamate symptoms". At present, scientific research can't find the exact reason to explain why those symptoms occur (see the picture above).
On the other hand, apart from the short-term discomfort of "monosodium glutamate syndrome", science has not proved that monosodium glutamate has long-term and serious harm to human body. Proving that a substance is bound to cause a disease is as difficult as proving that a substance is harmless to people, which requires a lot of time and research.
So far, it has not been proved that monosodium glutamate is harmful, but it does not mean that it is harmless.
We'd better consider the following questions:
Hazards may be discovered in the future.
Many commonly used chemicals have been "recognized and proved" harmless for a long time. As a result, many people suffer after a while, often too late. DDT and aspirin are good examples. There is no conclusive evidence that monosodium glutamate is harmful today (but there are a lot of experimental data, see below), and it may be harmful tomorrow.
"cocktail effect"
Any substance eaten in the stomach may be harmless in itself, but it is often dangerous to eat it with other substances. Because monosodium glutamate may be eaten with thousands of diets, and even with drugs (such as stomach drugs, birth control pills and medicinal materials), these risks cannot be detected and estimated.
Lose nutrition
Long-term use of monosodium glutamate (such as chicken essence or canned chicken soup) instead of real materials (such as fresh chicken) will lose nutrition, affect development and reduce disease resistance.
Eat a lot at a time
It is true that there is already a lot of monosodium glutamate in the human body. Generally, food itself contains monosodium glutamate, which is harmless to health. But in a short time (30-30 minutes), suddenly eating a large amount (a few grams) of monosodium glutamate is likely to be harmful.
Evidence of suspicious safety of monosodium glutamate
In addition to countless clinical records, many people feel uncomfortable after eating monosodium glutamate. In recent 40 years, there have been a lot of scientific research and other records that monosodium glutamate can seriously damage the physiology of animals or people in some cases. The following are some of them.
■ monosodium glutamate and development
The results of scientific experiments show that monosodium glutamate can hinder development and lead to obesity and other diseases:
In an experiment of 1970, a group of mice injected monosodium glutamate subcutaneously in the first ten days after birth. As a result, they become obese when they grow up-the weight of epididymal fat pad increases, the cell volume increases, and the number of fat cells decreases. In addition, compared with the control group, the larger cells in this group have a particularly poor lipolysis reaction to adrenaline, but a particularly strong anti-lipolysis reaction to insulin. Experts in charge of research believe that monosodium glutamate leads to obesity because monosodium glutamate changes the reaction of cells to adrenaline and insulin and increases the lipid content in adipose tissue.
In an experiment of 1974, scientists found that after long-term consumption of food containing 1-2% monosodium glutamate, the weight of weaned young rats was higher than that of the control group.
In an experiment of 1997, a group of mice were intraperitoneally injected with sodium glutamate equivalent to 4 grams per kilogram of body weight within the first ten days after birth. The results showed that when they grew up, they were abnormal in growth, endocrine and behavior, most of them were automatically divided into tails, all of them were obviously short and obese, and the ovaries, uterus and pituitary gland of female rats were smaller than those of the other control group. Another group of mice also injected the same amount of monosodium glutamate in the first ten days after birth, but injected it five times. In this way, the harm left by the above-mentioned typical monosodium glutamate is much less.
■ monosodium glutamate and vision
The results of scientific experiments show that monosodium glutamate can damage the retina and affect vision:
In an experiment of 1960, scientists injected monosodium glutamate into young rats by intraperitoneal injection at a dosage of 3.2 grams per kilogram of body weight. It was found that the retina of those mice was poisoned and damaged.
In an experiment of 1967, scientists injected sodium glutamate equivalent to 2.2-4.2 grams per kilogram of body weight into a group of mice for ten times within one to ten days after birth, and the retina was completely destroyed.
In an experiment of 1969, some mice of 9 to 10 days were injected subcutaneously with 4 grams of monosodium glutamate per kilogram, and then they were killed after 30 minutes to 48 hours respectively. It was found that the retina was seriously damaged-there were neural dendrites everywhere, nerve cells gradually changed, and finally the cells were swallowed up.
■ monosodium glutamate and vomiting
Scientific experiments show that monosodium glutamate can cause vomiting:
In an experiment of 1944, scientists injected casein hydrolysate or artificial amino acid mixture into dogs by intravenous injection, which caused dogs to have symptoms of nausea and vomiting.
1947, doctors treated uremia with sodium glutamate (a chemical substance almost the same as monosodium glutamate), which reduced the level of ammonia in blood. The results showed that 1 1 vomited after intravenous injection of 38 grams.
■ monosodium glutamate and hypertension
The content of sodium ion in monosodium glutamate is about 65438 03%. Excessive absorption of sodium ions by the human body may lead to hypertension. At present, Hong Kong people often absorb more sodium ions than they need in their bodies. In order to prevent hypertension, it is best not to eat monosodium glutamate. (The above is the view of the Hong Kong Nutrition Society)
Monosodium glutamate and fertility and heredity
The results of scientific experiments show that monosodium glutamate can destroy genetic factors, affect fertility and make offspring deformed;
In an experiment of 1965, the first group 14 rabbits, 10 female rabbits and 4 male rabbits were studied together. All females ate 25 mg of glutamic acid per kilogram of body weight for 27 consecutive days (males did not eat it). Later, two of the female rabbits became pregnant. The second group of rabbits, four female rabbits and two male rabbits, all ate 25 mg of glutamic acid per kilogram and the same weight of vitamin B6. The third group of rabbits, six female rabbits and one male rabbit, all ate 25 mg of glutamic acid per kg. The fourth group of rabbits, 20 females and 8 males, served as control. All glutamic acid and vitamins are tube fed. In the first group, two female rabbits delayed pregnancy and had degenerated fetuses in the uterus. The other two later miscarried and gave birth to deformed stillbirths. Two later became pregnant and gave birth in a normal period, but the rabbits showed various deformities and limb dysplasia, while the control group did not. In the second group, two rabbits were pregnant and gave birth to deformed rabbits. Two rabbits died shortly after birth, with deformed bones and atrophy of multiple organs. In the third group, three rabbits were pregnant, and all rabbits were deformed in limbs. The three groups of rabbits that ate glutamic acid were all male rabbits, testicular atrophy, and the rabbits born were all mutilated.
However, in two experiments, 1970 and 197 1, it was found that there was monosodium glutamate in the mother mouse, and the mice born were endocrine disorders when they grew up.
These two experiments also found that mice were injected with 2.2-4.2 grams of sodium glutamate (MSG) subcutaneously within 10 days after birth, and then killed at the age of 40. The results showed that these mice lost weight, testis and ovary died, adrenal gland and thyroid gland lost weight, and the levels of growth hormone and luteinizing hormone in the anterior pituitary gland decreased.
In an experiment of 1975, two groups of mice were injected subcutaneously with sodium glutamate equivalent to 4 grams per kilogram of body weight in the first ten days after birth, one group injected 1 time and the other group injected 5 times. As a result, when they grow up, the pituitary gland, adrenal gland, ovary and testis are smaller than the other group of mice.
In another experiment of 1977, a group of mice were injected with monosodium glutamate subcutaneously every day from the second day to the eleventh day after birth. From the beginning, the amount was 2.2 grams per kilogram of body weight. As a result, both male and female mice have reproductive problems when they grow up. The mother mouse is pregnant less, and the mice produced are particularly small; The fertility of male rats is also greatly reduced.
In another experiment of 1977, a group of newborn mice were subcutaneously injected with 2.5-4.2 mg of monosodium glutamate per kilogram of body weight. The results showed that the activity ability was not affected, but when she grew up, she was short and fat, and the fertility of female mice was disturbed.
■ monosodium glutamate and intelligence
The results of scientific experiments show that monosodium glutamate can cause permanent brain damage, which can't be seen at an early age:
In an experiment of 1970, 65 rats of 10 ~ 12 days old were fed with different doses of monosodium glutamate at one time, each kilogram of body weight was 0.5g, 0.75g, 1.0g and 2.0g, of which 10 rats were not. Three to six hours after feeding, all mice were killed by perfusion. The results showed that 565,438+0 mice had obvious brain damage-nerve cells died one after another, and the rate of death was directly proportional to the dosage of monosodium glutamate. 52% of them ate 0.5g, 865,438+0% ate 0.75g, 65,438+0.0 per kg body weight. If mice are injected with the same amount of monosodium glutamate subcutaneously, the results are exactly the same. The experiment also found that if monosodium glutamate and saccharin (aspartame) are eaten together, the damage to the brain will be twice as serious.
1970, another group of scientists did another experiment. Six 9-to 10-day-old mice were injected with 10% monosodium glutamate solution, equivalent to 2 grams per kilogram of body weight. As a result, a typical brain injury caused by monosodium glutamate appeared.
In an experiment in 197 1 year, scientists injected 2-4g monosodium glutamate (0. 1 ml in distilled water) into a group of mice three to ten days after birth by subcutaneous injection. Another adult mouse was injected subcutaneously and intraperitoneally with 6- 10g (volume 1ml) respectively. Another group of mice were injected with sodium chloride. 72 hours after injection, all mice were killed and the brain tissue was observed by microscope. It was found that 95% of the hypothalamic arcuate nucleus was destroyed in mice injected with monosodium glutamate.
In another experiment of 197 1, scientists injected sodium glutamate equivalent to 1 g per kilogram of body weight within two to four days after birth, and killed mice in batches one hour, three hours, six hours and twenty-four hours after injection. The brain tissue was observed by microscope, and it was found that all mice had necrosis in hippocampus and hypothalamus.
Another group of mice of the same kind were injected with monosodium glutamate equivalent to 5 mg per kg body weight subcutaneously at 17 and 18 after pregnancy. 3 hours, 6 hours and 24 hours after injection, the fetus was taken out in batches to examine the brain tissue, and it was found that the nuclei in the middle and arch were damaged.
In an experiment of 1972, scientists selected eight mice from ten pregnant mothers and divided them into four groups, that is, each mother gave birth to two mice in each group, and then injected monosodium glutamate equivalent to 1.25 g, 2.5 g and 5 g per kilogram of body weight through the abdominal cavity every day from the fifth to the tenth day, while the control group injected water. On the 2nd1day after birth, mice were put into different cages to live alone. Three months after birth, behavior was tested by three methods-natural motor nerve activity, T- maze and proportional food fortification test. The results showed that mice injected with a large amount of monosodium glutamate had less natural motor nerve activity and learned T- maze slowly, but the behavior of learning food reinforcement was not affected.
In an experiment of 1974, scientists used the methods of clamping the thoracic aorta and injecting drugs respectively, which greatly increased the blood pressure of dogs, which led to the extravasation of Evans blue protein in the brain and damaged the tissues of the brain and cerebellum. Usually, brain tissue is damaged only because of lack of oxygen, but if glutamate exists in the tissue, the damage will be much more serious. From the results of this experiment and other experiments, medical professionals believe that people with various diseases (such as eye inflammation, vitamin B6 deficiency, patients who have undergone some operations, and women who take birth control pills) may have weakened their ability to resist the extravasation of other substances, and monosodium glutamate may easily damage brain tissue.
Scientists have done various experiments with animals and found that many different kinds of animals (including mice, rats, rabbits and monkeys) are exposed to monosodium glutamate in childhood, which will cause brain damage. Ernie and Sapu, two American scientists, commented after an experiment on rhesus monkeys: "When these monkeys were young, a small part of their brain cells were damaged without any signs at all, which proved that brain trauma is a subtle process. If a human baby suffers the same injury in a normal environment, no one may see it. " In other words, if children are fed food containing monosodium glutamate, their brains may be constantly traumatized, and their parents will never notice.
■ monosodium glutamate and heart disease
Scientific experiments show that monosodium glutamate can cause heart disease;
In an experiment in 1962, scientists injected a large amount of glutamic acid into rabbits by intravenous injection. As a result, myocardial injury occurred in rabbits one after another, which was proved to be due to arterial tension caused by glutamic acid. Scientists studied the cut heart separately and found that a large amount of glutamic acid slowed down the operation of the heart, increased the contraction of the heart and compressed the coronary vessels. A large amount of glutamic acid will stop the heart.
■ monosodium glutamate and cancer
Famous doctors in the west and Asia loudly pointed out that it may be extremely dangerous to give children food containing monosodium glutamate. Professor Huang Xueben, director of the Department of Pediatrics at the University of Singapore, said it was dangerous because monosodium glutamate is a nerve conductor. After being eaten in the body, it becomes a substance, which transmits the stimulation of one nerve cell to another nerve cell, thus causing "China restaurant disease", which makes some adults feel dizzy, blushing and short of breath, and "disaster is coming". Professor Huang said in a letter to Penang Consumers Association: "I have seen babies with tumors. At that time, the only clue that could explain the disease was that the baby ate the baby food bought in the supermarket, which contained a lot of monosodium glutamate. Later, the baby stopped eating baby food and the tumor disappeared. "
Japanese scientists have recently done research and found that monosodium glutamate can form carcinogens at high temperatures. Daily cooking temperature is not high, even fried food will not reach the above high temperature, but it may happen during barbecue (barbecued pork, roasted meat, roast duck, tourist barbecue), and it may be dangerous if meat contains monosodium glutamate (mostly in seasoning).
■ monosodium glutamate and death
197 1 year, the National Institute of Health of Japan experimented with chickens and fed them with a solution containing 2.6% monosodium glutamate. Results Most chickens died within three days, and a large number of white material were found in the heart, air bag, liver, muscle and other internal organs of the corpse. According to the report of this study, chickens refused to eat one day or half before they died. "Stand there, close your eyes, and then fall to the ground, screaming weakly, with stiff feet, trying to stand up but losing your balance."
Local middle school students did the same experiment and found that chickens fed with 2.6% monosodium glutamate solution died within 19 days. Another group of chickens were fed the same food, but without monosodium glutamate, and all survived in the experiment. *
What is the maximum daily intake of monosodium glutamate?
The United Nations "World Health Organization" has formulated a safety standard, suggesting that the maximum intake of monosodium glutamate per person per day is1.20mg, which is equivalent to 4-6g for adults (about one teaspoon) and1-4g for children (but this standard is not applicable to infants, and infants under 12 weeks should not eat monosodium glutamate or any food additives. )
The World Health Organization recommends the maximum daily dose of monosodium glutamate.
Weight and dosage
10kg (about 2 years old)1.2g.
20 kg (about 5 years old) 2.4 g
30 kg (about 8 years old) and nbs
References:
References:
Respondent: Moto William II-Assistant Level 3 12-5 10:06.
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Harm of monosodium glutamate to human body
The chemical name of sodium glutamate is sodium glutamate. When monosodium glutamate is dissolved in water, it will give off deceptive meat flavor, stimulate taste buds and add flavor to food.
1908 One day, a chemistry professor found that his wife's soup was very delicious at dinner. He asked his wife, and her answer was only kelp. After dinner, the professor sat at the table in deep thought. He relished the delicacy of kelp and decided to uncover the secret of kelp delicacy. The professor took a lot of kelp and made a series of chemical analysis. After half a year's efforts, he finally extracted 2 grams of delicious substance from 10 kg of kelp, and its chemical name was sodium glutamate. Adding a small amount of sodium glutamate to dishes or soup greatly increases the flavor, which he calls "flavor element".
MSG is harmful to human body. When eaten in excess, it will directly endanger human health. Scholars put forward a medical case of "Chinese restaurant syndrome", saying that Chinese restaurants use a lot of monosodium glutamate when cooking food, which makes people feel uncomfortable after eating, leading to numbness of upper limbs, asthma and dizziness. The reason is that sodium glutamate, the main component of monosodium glutamate, will decompose into glutamic acid and tyrosine if it is excessive. Tyrosine can interfere with the normal activities of brain cells and inhibit the physiological functions of brain nerves, thus causing discomfort.
In the process of digestion, monosodium glutamate can decompose glutamic acid, which is converted into an inhibitory neurotransmitter by enzyme catalysis in brain tissue. When monosodium glutamate is ingested too much, this inhibitory neurotransmitter will inhibit various nerve functions in the human body, resulting in a series of symptoms such as dizziness, headache, drowsiness and muscle spasm. Some people will be anxious and flustered; Some people with sensitive physique may even feel sore bones and muscles. In addition, excessive inhibitory neurotransmitters can also inhibit the secretion of thyroid stimulating hormone in human hypothalamus, thus hindering the development of bones, especially for children. The increase of glutamic acid content in blood limits the utilization of essential minerals such as calcium, magnesium and copper. In particular, glutamic acid can combine with zinc in blood, and the unusable zinc glutamate is excreted, resulting in zinc deficiency in human body. Zinc is an important nutrient for infants' physical and intellectual development. Therefore, infants and nursing mothers should fast or eat less monosodium glutamate. In addition, Japanese researchers believe that long-term excessive consumption of monosodium glutamate may lead to thinning of retina, decreased vision and even blindness. Eating too much monosodium glutamate often makes you thirsty. This is because monosodium glutamate contains sodium, and excessive intake will lead to high blood pressure. People over the age of 60 are particularly sensitive to sodium intake, so the elderly and people suffering from diseases such as hypertension, kidney disease and edema should especially eat less monosodium glutamate.
The intake stipulated by the World Health Organization is 1.20 mg/kg body weight per adult per day (about 50 kg body weight, 6 g monosodium glutamate per day). It should be noted that monosodium glutamate cannot be heated, because once heated (120 degrees Celsius or above), sodium glutamate becomes sodium pyroglutamate. This is a harmful substance, which is difficult to excrete. Although sodium pyroglutamate is not toxic, it will accumulate in the body, and at the same time, there will be heartbeat, hand trembling, insomnia and mild excitement. In addition, don't put monosodium glutamate into alkaline and acidic foods, because monosodium glutamate will react chemically when it meets alkali, and disodium glutamate with bad smell will be difficult to dissolve when it meets acid. It is not appropriate to put monosodium glutamate in cold salad, because monosodium glutamate is difficult to dissolve.
So, how much monosodium glutamate is appropriate for each meal? The researchers suggest that each dish should not exceed 0.5 mg. The severity of the side effects of monosodium glutamate will vary according to one's physique. Therefore, everyone should pay attention to health while enjoying delicious food.