Sour dishes, such as sweet and sour fish or sweet and sour pork ribs, should never have MSG added. This is because MSG is alkaline. When added to an acidic dish, a neutralization reaction occurs chemically, producing salt and water, which will ruin the flavor of the dish.
So, can it be added to alkaline foods? Practice has shown that in alkaline foods, the sodium glutamate in MSG also loses its umami flavor. Therefore, MSG is best suited for foods that are not distinctly acidic or alkaline. When adding MSG, also pay attention to the saltiness of the dish. If it is too salty, the sodium ions from the salt will mask the sodium glutamate, and the umami flavor will not be noticeable. If it is too bland, the umami flavor of the MSG will not be "brought out."
Finally, temperature is also important. The solubility point for MSG is 85°C. Below this temperature, the MSG structure has not broken down, and above this temperature, it should not be added, as it will not produce a umami flavor.