1, resulting in a different color "culprit" is the acidity of the water, alkaline tap water will make the bean soup red, and add a little lemon juice or white vinegar, the tap water into a weak acidic, cooked out of the bean soup is green. Therefore, in order to cook the green bean soup to relieve the summer heat, as long as the use of pure water or acidified tap water, you can easily achieve the purpose.

2, high concentrations of iron ions do cook green bean soup to pink, and under certain conditions it can even turn purple-black.

3, green bean soup turns red because the flavonoids are oxidized, but the bean soup cooked with pure water will not turn red even if it is left for a period of time, so it can be seen that oxygen is a factor in the redness, but not the main factor.

It should be noted that the flavonoids in mung beans have a strong antioxidant properties, under normal circumstances can completely resist the damage of oxygen, but they are afraid of alkali, when the alkaline water cooking mung beans, flavonoids antioxidant barrier is destroyed, it is easy to be oxidized by oxygen into a reddish color.

Expanded Information

Mung beans boiled for a different time with different efficacy

1, with a high fire can be boiled for about 10 minutes, do not cook for a long time. This boiled soup color green, relatively clear, the best summer effect.

2, mung beans have a detoxifying effect, but some people drink but not achieve the desired effect, one of the reasons is not mastered the cooking time. Skin prickly heat, rash, may be because the body is too hot, if you want to drink green bean soup, cooking time should be extended to 30 minutes to 1 hour is appropriate, beans cooked to blossom, the soup becomes cloudy, drink up the feeling of rustling, so that the green bean soup heat detoxification effect is good.

People's Daily News - why turn red, can use iron pot? Simmering mung bean soup five questions

People's Daily News - mung bean soup cooking how long is appropriate? Different time different efficacy