Soup stock is generally not sold. Hotels use their own products. "If you use it at home, just add a little soup treasure." Actually, you don't have to be so professional at home. Broth is mainly made from fresh meat such as old hens by slow fire. "The general cooking time is 3 days and 3 nights." Every meal should be heated and boiled. Soup goes bad easily, especially in summer. I don't advocate making it at home.