Is mung bean soup red or green? Netizens in the north and the South quarreled about it again. Mung bean soup is red and green. In fact, different regions and water quality will lead to different colors. Mung bean soup turns red because it contains phenols. As long as boiling will dissolve in the soup, it will gradually change color due to the effect of oxygen.
1. Length of time
Generally speaking, the green bean soup seen from childhood will change color. The green bean soup just out of the pot is usually thick and green. After a while, you will find that the cold green bean soup in the pot is already a thick red color. The reason is that the polyphenol antioxidants in mung bean skin are affected in the air and cause discoloration.
PH value of water quality
2. many families are used to boiling mungbean soup with pure water. And the mung bean soup cooked with tap water, often out of the pot, almost every second in the red bottom of the soup.
Scientific research shows that different pH values of tap water can also lead to the length of discoloration time. If the tap water is acidic, the color of the green bean soup is very small. If the tap water is alkaline, it will often run towards the red color after contacting the air.
3. Catalysis of iron pot
When cooking mung bean soup, the elderly at home will suggest not to cook it in an iron pot. This common sense seems to have been instilled since birth. So does it have a scientific basis? It turns out that iron can easily catalyze the oxidation of various vitamins and other substances, such as polyphenols in mung bean skin. Therefore, the best way to boil mung bean soup is not to use an iron pot, otherwise, it will boil a thick red mung bean soup.
4. Cold boiling of water
If someone cooks mung bean soup with supercooled water or boiling water, he will find that the soup often turns red or changes color quickly after it leaves the pot. The reason is very simple and easy to understand. It takes a long time to cook in cold water. Of course, the oxidation is longer, and the color of the soup is naturally easy to change. Boiling with boiling water, so that it can not contact with the air to produce oxidation reaction, the soup color naturally clear.