The principle of green bean water becomes red is very simple, is the green bean soup from the epidermis of green beans partially dissolved phenolic substances in the air under the action of oxygen oxidation polymerization results. Therefore, open the lid to cook mung bean porridge is easy to change color, with the pressure cooker to cook mung bean porridge is not easy to change color.

The color turquoise green bean soup, health effects are much better, discoloration of green bean soup is obviously worse. Analysis of the data showed a highly significant correlation between bean soup color and antioxidant activity. Add a little salt, add a little citric acid, are conducive to improve the antioxidant effect, and add alkali cooking will greatly reduce the antioxidant effect.

Cooking time to see the soup, the beginning of about 10 minutes, the starch in the green beans did not dissolve, the soup is clear and transparent. With the extension of the cooking time, the soup gradually turbid, starch and protein gradually dissolved. As both starch and protein can combine with polyphenols, it will reduce the effective content of antioxidant substances. As with other colored beans, the antioxidant substances in mung beans, such as tannins and flavonoids, are mainly found in the skin, including mungin and isomungin. Research has also shown that the heat-reducing components of mung beans are found in the skin and have little to do with the starch.

It seems that the old-timers were right, and it is likely that the green and clear bean soup is more effective in clearing up the heat.