Why is mung bean soup red?

Mung beans are green in appearance, and people naturally think that the mung bean soup made from them should also be green. However, when you cook mung bean soup yourself, you find that the cooked mung bean soup is red liquid. Why is this? It is obviously a soup made from mung beans and water, why does it turn red? Many people are puzzled by this, and today the editor will explain it to you in detail.

1. Mung bean soup will change color

In fact, when you cook mung bean soup, if you observe carefully, you will find that the mung bean soup will actually change color. The mung bean soup that is first cooked in the pot and the mung bean soup that has just come out of the pot are both emerald green, but after cooling it down for a while, you will find that the mung bean soup turns red. This is because the polyphenols in the mung bean skin oxidize with the oxygen in the air, causing its color to change.

2. Related to water quality

The mung bean soup is red after being cooked, which is related to the water quality. Because the tap water in the household is more or less alkaline water, the mung bean soup cooked with it will turn red immediately after the fire is turned off. But if you use slightly acidic water to cook the mung bean soup, the chance of it turning red after cooking is very small. If you insist on using pure water to cook the mung bean soup, it will not turn red no matter how long it is stored after cooking.

3. Related to the pot

The mung bean soup usually cooked is red, which has a lot to do with the pot used to cook the mung bean soup. Mung bean soup cooked in an iron pot is likely to be red, while mung bean soup cooked in stainless steel or aluminum pots is not easy to change color. This is because the trace element iron contained in the iron pot will react with the mung beans to generate iron oxide, which will be released into the cooked mung bean soup. Iron oxide is a rich red, so people will find that the cooked mung bean soup is dark red.

How to cook mung bean soup without changing color

If you want the cooked mung bean soup to be emerald green, it is best to choose pure water for cooking, and add a small amount of vinegar during the cooking process to make the water slightly acidic. This way, the cooked mung bean soup will be emerald green in color, and it will have a better effect in relieving heat and reducing body temperature.