How to make the old fire soup in those high-end hotels?

The so-called old fire soup refers to the soup with long boiling time, sufficient heat and delicious taste. The traditional practice is to boil in a clay pot, add the soup after the water boils, boil, turn off the heat and cook slowly for 2-4 hours.

"Old fire soup" is usually boiled in cold water, boiled and stewed for several hours. Traditionally, the longer you cook, the better the soup tastes. Actually, it is not. First, let's look at the influence of the temperature of soup on food. The umami substances in animal food, that is, low molecular nitrogen-containing compounds (such as creatine, creatinine, purine base and a small amount of amino acids), can be dissolved in soup at low temperature, that is, before protein denaturation. These nitrogen-containing extracts can make soup delicious and stimulate people's appetite, so it should be a good habit to drink a proper amount of soup before meals. As for water-soluble vitamins (B and C) and a small amount of inorganic salts (sodium, potassium, etc. In food, they can be dissolved in soup during cooking, but the quantity is not much. Finally, let's look at the soup residue. The solid content in a pot of soup accounts for about 2% ~ 5% of the soup, which is a very small part of the soup materials used; Protein in the soup is solidified and denatured when heated, and the denatured protein is insoluble in water and remains in the cooked soup residue. According to the above analysis, it is not difficult for us to see that it is a wrong eating habit to drink soup without meat (soup residue) and have no nutrition in protein at all.

In addition, if the food is cooked for a long time, the vitamins in the food, especially the water-soluble vitamins (vitamin B and vitamin C), will be destroyed, which is another unscientific aspect of "Lao Huo Tang".