Why does mung bean water turn red?

Summer is here and the weather is scorching hot. Buy some mung beans, add water, and boil them to make mung bean porridge. Drinking it can quench your thirst, clear away heat and relieve summer heat. It is very comfortable. But if you are careful, you will find that mung beans are green. After being boiled into mung bean porridge, they somehow turn red. Can you drink the red mung bean porridge? Is there any way to prevent mung bean porridge from turning red?

What is the difference between red and green mung bean soup?

Mung bean skins contain phenols. If they come into contact with oxygen in the air during cooking, an oxidative polymerization reaction will occur and they will turn red. Phenols are actually an antioxidant that can remove free radicals that are harmful to human cells. From this point of view, the green mung bean soup has a low degree of oxidation of phenolic substances, strong antioxidant activity, and better effect in scavenging free radicals. In comparison, green mung bean soup is healthier than red one.

Is there a way to stop mung bean soup from turning red?

The red color of mung bean soup is mainly caused by oxidation reaction. Therefore, as long as the oxidation problem is solved, the mung bean soup can remain green. Usually, the main factors affecting the oxidation of mung bean soup are the acidity and alkalinity of the soup and the oxygen content in the air. You can try two tricks:

1. Use a pressure cooker to cook mung bean soup

Oxidation reactions require the participation of oxygen. Using a pressure cooker can effectively isolate the oxygen outside the pot and prevent the phenolic substances in mung beans from oxidizing and polymerizing to produce red substances. However, this mung bean soup needs to be consumed quickly, otherwise when it is exposed to the air, it will still undergo a slow oxidation reaction and eventually turn red.

2. Add a little white vinegar or lemon juice to the water

Through experiments, it was found that the degree of color change of mung bean soup would be different when boiled with water of different acidity and alkalinity: the color change was very small after boiling with acidic tap water, while the color change was very rapid after boiling with slightly alkaline tap water. Therefore, adding acidic substances such as white vinegar and citric acid to the water can effectively prevent the mung bean soup from changing color.

Mung bean soup is rich in nutrients

People with weak constitution should not drink

Mung bean soup has the effects of clearing away heat, detoxifying, quenching thirst and relieving summer heat. Every 100 grams of mung beans contains 22.1 grams of protein, 0.8 grams of fat, 4.5 grams of carbohydrates, 313 milligrams of calcium, 6.4 milligrams of iron, etc. The protein in mung bean is a complete protein containing more lysine, its content is almost three times that of japonica rice, and mung bean protein has the effect of detoxification.

Although mung bean soup is good, you should not drink too much. The oligosaccharides contained in mung beans can easily cause bloating, and mung beans themselves are difficult to digest. From the perspective of traditional Chinese medicine, mung beans are cool in nature, and drinking too much can easily affect the spleen and stomach. People with weak constitution should not drink mung bean soup, as it will cause diarrhea or reduced immunity of the digestive system.

All experts have reminded that it is recommended that adults should not consume more than 50 grams per day.