In China's time-honored culinary culture, the character "鲜" (xiān), meaning umami or deliciousness, has always held a significant position. As early as the Zhou Dynasty, there is a legend that combining fish and lamb created a delicious flavor and also gave birth to the character "鲜". Since its inception, monosodium glutamate (MSG) has played a significant role in enhancing the umami of food. However, debates and issues surrounding the use of MSG have continued to trouble people.
Is MSG beneficial?
The main component of MSG is sodium glutamate, which is produced from grain through microbial fermentation, extraction, and refining. The human tongue has specific amino acid receptors. When MSG is consumed, it stimulates these amino acid receptors on the taste buds, creating a savory taste that enhances appetite and induces the secretion of digestive juices, thereby promoting the digestion and absorption of food.
The glutamate produced when MSG is absorbed and broken down in the intestines is one of the amino acids the human body needs. It is involved in the formation and repair of body tissues and various important physiological functions. In the liver, it participates in glucose metabolism and the detoxification process, reducing the concentration of toxic ammonia in the blood. In the brain, it participates in the metabolism of proteins and sugars, which can to some extent improve the function of the brain and central nervous system.
Therefore, MSG has certain benefits for human health. Currently, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have listed MSG as a recommended food additive.
Is MSG harmful?
For a period, some Westerners experienced symptoms like sore throat, headache, fever, vomiting, and dizziness after eating at Chinese restaurants. They called this phenomenon "Chinese Restaurant Syndrome". It was once thought that this was caused by the large amount of MSG used in Chinese cooking. After a series of investigations and studies, it was found that so-called "Chinese Restaurant Syndrome" is not related to MSG, but to individual allergies to foods such as grains and wheat, which alleviated people's panic about using MSG.
However, when excessive amounts of MSG are used, the glutamate from its breakdown can be converted by enzymes in the body into substances that inhibit nerve function, leading to symptoms like dizziness and drowsiness. Some people may experience a rapid heartbeat and irritability. Increased glutamate in the blood can also limit the absorption of essential trace elements such as calcium, magnesium, zinc, and copper. Furthermore, a Japanese study showed that long-term excessive use of MSG may lead to retinal thinning, decreased vision, and even blindness. Therefore, while affirming the beneficial effects of MSG, paying attention to scientific usage methods is key to avoiding harm to human health.
Expert reminders:
MSG should not be added to dishes that emphasize their original flavor, have a strong umami taste, or are sweet. When cooking to highlight the original flavor, or when making dishes like mushrooms, shiitake mushrooms, chicken, beef, and eggs, these ingredients themselves contain large amounts of substances similar to MSG, such as glutamate and glycine, so there is no need to add MSG.
MSG should not be added to dishes with a strong alkaline pH. Because MSG can react with strong alkalis to form disodium glutamate, which has an unpleasant odor, MSG loses its original umami-enhancing effect. Therefore, when cooking strongly alkaline dishes such as kelp, squid, sea cucumber, and shrimp, be careful not to add MSG to avoid losing the umami or affecting the taste.
MSG is also not suitable for acidic foods. Because MSG is not soluble in acidic solutions, the lower the pH, the lower the solubility. Therefore, MSG should not be added to dishes like sweet and sour or vinegar-based dishes.
Expert reminders on the scientific use of MSG:
The addition of MSG should be moderate. No more than 0.5 grams of MSG should be added per dish, and the daily intake per person should not exceed 6 grams.
It is best to add MSG just before the dish is finished cooking. Chinese cooking often involves long heating times, which can cause MSG to develop a bitter taste. Also, MSG can caramelize at temperatures above 120°C, forming carcinogenic sodium pyroglutamate. When a dish is almost ready, the temperature drops to 70°C-90°C, which is the optimal temperature for dissolving MSG and when the umami is strongest. However, if a dish requires thickening with starch, MSG should be added before the thickening, so it is best not to add MSG to thickened dishes.
When using MSG at low temperatures, it should first be dissolved in warm water. Because MSG does not dissolve easily at low temperatures, it cannot be added directly to cold dishes. At this time, powdered MSG is easier to dissolve and mix than crystalline MSG. The same principle applies to making fillings for dumplings. However, after the filling is made into buns or dumplings and subjected to long periods of high-temperature frying, steaming, or boiling, the MSG will denature. Therefore, it is best not to add MSG to fillings.
Expert reminders for special populations to avoid MSG:
Lactating women and infants should preferably avoid MSG. The glutamate in MSG can bind with zinc in the blood, reducing its concentration. Glutamate enters the infant's body through breast milk or soup, forming poorly absorbed zinc glutamate which is excreted, leading to zinc deficiency in the infant. This can range from loss of appetite and poor taste to a weakened immune system, making the infant prone to colds, pneumonia, hepatitis, and other infectious diseases. In severe cases, it can lead to intellectual disability, growth and development disorders, anemia, enlargement of the liver and spleen, and incomplete development of the reproductive organs and secondary sexual characteristics.
MSG contains a certain proportion of sodium. Excessive use of MSG can cause thirst, and people over 60 are more sensitive to sodium intake. Therefore, the elderly and patients with hypertension, kidney disease, metabolic syndrome, and other illnesses should eat less or no MSG.
Chicken Essence: More Complex Ingredients than MSG
Chicken essence is not pure MSG; its composition is very complex. Chicken essence is a flavor enhancer and seasoning made from basic ingredients like chicken, chicken bones, and eggs, which are steamed, pressure-cooked, and extracted, and then blended with substances like salt, sugar, MSG, chicken powder, spices, inosinate, guanylate, and chicken flavor essence.
The purity of sodium glutamate in chicken essence is about 40%, while in MSG, it is over 80%. In terms of specific usage, the amount of chicken essence used depends on individual preference and can be added until the desired deliciousness is achieved. In contrast, MSG is relatively pure, and its usage is more stable.
Expert reminders:
Chicken essence contains salt, so when using it to season dishes, be careful to add less salt.
Chicken essence contains nucleotides, and the metabolic product of nucleotides is uric acid, so people with gout should use it sparingly.
Chicken essence is less soluble than MSG, so if it is not being used in soups, it should be dissolved first.
Chicken essence contains salt and is highly hygroscopic, so it should be sealed after use to prevent the nutrient-rich chicken essence from breeding microorganisms and contaminating food.
If too much chicken essence is added, it can destroy the original flavor of the dish.