The reason why mung bean soup can clear away heat and detoxify is mainly because of polyphenols in mung bean skin. A large number of polyphenols will change color as soon as they see oxygen.
Boil it in boiling water in a pot, cover it, and you won't be exposed to oxygen, so you can stay green for a while. It has not been oxidized, and it has the strongest effect of clearing away heat and toxic materials. People who want to clear fire can drink quickly.
Don't use an iron pot to make soup. Cooking mung bean soup in an iron pan will affect the color of the soup. This is because iron ions often form "complexes" with polyphenols, and the color is dark brown, which makes the soup dark and deep.
Iron not only catalyzes the oxidative decomposition of vitamins, but also reacts with polyphenols in medicinal materials and fruits, thus affecting the efficacy or color. Use a casserole or stainless steel pot, and you won't have these troubles.