The antioxidant capacity of red bean soup was significantly lower than that of green bean soup. The redder the color, the lower the antioxidant capacity. Generally speaking, the stronger the antioxidant capacity of the bean soup, the better the heat relief effect.
What water should I use to boil green bean soup? The study found that the green bean soup was made of tap water, purified water and pure water, and the colors of the three kinds of bean soup were orange red, light yellow and green. Further screening revealed that the “culprit” was the acid and alkaline nature of the water. The weak alkaline tap water could make the bean soup turn red, while the tap water became slightly acidic when added with lemon juice or white vinegar. Therefore, to make the green bean soup to relieve the heat, you can easily achieve the goal by using pure water or acidic tap water.
Can't you use an iron pan? Studies have found that high levels of iron do indeed make mung bean soup pink and, in some cases, purple black. But to achieve this effect, the amount of iron in poached mung bean water is more than 100 times that of tap water. In life, unless pure white vinegar is boiled in an iron pan, the iron will dissolve in large quantities, while normal drinking water will not dissolve the iron in an iron pan. That said, the iron pot is not the main reason for the green bean soup to turn red. So, there's no problem cooking green bean soup in an iron pan.
Do you cover the pot? Mung bean soup turns red because flavonoids are oxidized, but soy soup made with pure water will not turn red for a while, so oxygen is the cause, but not the main factor. It should be noted that the flavonoids in mung beans have strong antioxidant property and can resist the damage of oxygen under normal conditions. However, they are very resistant to alkali. When the mung beans are boiled with alkaline water, the antioxidant barrier of the flavonoids is damaged and easily oxidized to red by oxygen. Therefore, as long as the appropriate water boil green beans, cover the lid, green bean soup is green; But if you use the wrong water or add the alkaline to the water, even though the soya bean soup is green when covered, the soya bean soup quickly discolors as soon as you stop heating it or pour it into the bowl.
Under cold water or under hot water? The choice depends largely on how you want to eat mung beans. If you want to have clear soup, it is recommended to add mung beans after boiling water and cook for 8 to 10 minutes to pour out the clear soup for drinking. At this time, the beans are not ripe yet, so you can continue to cook the mung bean paste or add rice to cook the mung bean porridge. If you want to eat it with your soup, soak the mung beans in cold water for an hour.