The daily intake should not exceed 120 mg per kilogram of body weight per person.
(1) The dosage should not be excessive.
For infants under one year of age, it is best to avoid MSG. A small amount during cooking is sufficient to achieve a savory flavor.
(2) It should not be added too early when stir-frying.
MSG should generally be added when the dish is almost ready or just after it is taken out of the pan. At this point, the food temperature is around 70-90°C, which is the optimal temperature for MSG to dissolve and provides the strongest umami flavor. Conversely, adding it at high temperatures will cause the sodium glutamate in MSG to caramelize into sodium pyroglutamate when the temperature exceeds 120°C. This caramelized compound has no umami flavor and can be toxic. Therefore, fried foods, which are typically cooked at temperatures above 120°C, should not use MSG.
(3) It should not be used in strongly alkaline foods.
The sodium in sodium glutamate is highly reactive and easily undergoes a chemical reaction with alkali, producing disodium glutamate, which has an unpleasant odor and loses its seasoning effect. Therefore, strongly alkaline dishes like those containing kelp or squid are not suitable for adding MSG.
(4) It should not be used in sour dishes.
MSG does not dissolve well in acidic environments; the higher the acidity, the lower the solubility. Adding MSG to such dishes is therefore ineffective.
(5) Dishes consumed by mothers within three months postpartum and by infants should not contain excessive MSG. This is because the sodium glutamate in MSG can enter an infant's body through breast milk or food. It then specifically binds with zinc in the infant's blood to form zinc glutamate, which is not absorbed or utilized by the body and is excreted in urine, leading to zinc deficiency in the infant.
(6) When making cold dishes, it is not advisable to add both soy sauce and MSG, as this will cancel out the umami flavor.
(7) It should not be used as a filling.
When used as a filling in dumplings or similar foods, whether steamed or boiled, MSG will be exposed to sustained high temperatures, causing it to denature and lose its seasoning effect.
(8) MSG should not be added directly to cold dishes; it must first be dissolved in boiling water.
MSG dissolves fully only at temperatures above 70°C. Since cold dishes are at a low temperature, adding MSG directly will cause it to not dissolve properly. If a small amount of warm water is used to dissolve the MSG first, and then it is poured over the cold dish and mixed well, the result is much better. Furthermore, using powdered MSG rather than crystalline granules for cold dishes makes it easier to dissolve and mix, providing a better umami-enhancing effect.
(9) It should not be used with ingredients that are already exceptionally savory (such as mushrooms, shiitake, chicken, beef, fish and shrimp from rivers and seas, or very fresh vegetables). This is because these ingredients contain inosinate and guanylate, which provide their own natural umami. Adding MSG can actually result in an inferior taste.