Mung bean soup is a kind of heat clearing and heat relieving drink that many people like very much in summer. Is it very pleasant to drink a bowl of mung bean soup in summer? Then how to boil mung bean soup without discoloration? What color is it with better effect?
In fact, the mung bean soup that I saw when I was a child is to change color. Just put the mung bean into the boiling water pot, cover it, and cook for a few minutes. The Green Mung bean soup is boiled out, but the bean is still intact, not broken at all. My mother told me that this kind of soup is especially good for relieving summer heat, so we should drink it quickly, otherwise it will change color and the effect will be discounted.
Sure enough, drink this bowl of mung bean soup, and then open the lid of the pot. The color of mung bean soup is not so green. After they are filled out, the color becomes darker and darker, from green to yellow, from yellow to orange, from orange to red. In old Beijing restaurants, free mung bean soup is given in summer, and it is also red. When cooking mung bean porridge, there are similar phenomena. The principle of reddening is very simple. It is the result of oxidative polymerization of phenols partially dissolved from mung bean skin in mung bean soup under the action of oxygen in the air. Therefore, it is easy to change color when cooking mung bean porridge with the cover open, and it is not easy to change color when cooking mung bean porridge with the pressure cooker.
So, do you think the mung bean soup will turn red. Our experiments show that mung bean soup can be kept unchanged for a long time. The secret of the problem is that the water used to cook beans is different. Using tap water, mineral water, purified water and deionized water respectively to cook mung bean soup, the result is that the color of deionized water is the greenest, and it will not change for a long time. The color of mung bean soup boiled in tap water changes the fastest. It becomes dark almost every minute after contact with the air, and soon turns red. Obviously, it is caused by different water quality.
We adjusted the tap water to different pH value to cook mung bean soup, and found that the pH value can greatly affect the discoloration effect of the soup. The discoloration of acidic tap water is very small, while that of slightly alkaline tap water is very fast. However, for deionized water, no matter what pH, the color change is very small.
In this way, we can get a simple way to cook mung bean soup without discoloration - if there is a reverse osmosis water purifier at home, it can be boiled directly with pure water, there is no problem. If not, just add half a teaspoon of vinegar or squeeze in half a teaspoon of lemon juice when cooking the mung bean soup to keep the green color in the air for a long time.
So, what's the difference between green and red soup in terms of health effect?
We also tested the antioxidant properties and found that the scavenging ability of mung bean soup was closely related to its color. Green color of mung bean soup, the effect is much better, the color of mung bean soup is obviously worse. Data analysis showed that there was a significant correlation between the color and antioxidant activity of mung bean soup. Adding a little salt and a little citric acid can improve the antioxidant effect, while adding alkali to cook can greatly reduce the antioxidant effect.