The principle of reddening is very simple, which is the result of oxidative polymerization of phenols 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 open cover, but it is not easy to change color when cooking mung bean porridge with pressure cooker. There are several ways to keep red.

1, boil with purified water.

Step 2 add vinegar when cooking

But not too much, or it will taste strange.

3. Cover the pot and cook and drink quickly.

When cooking mung bean soup, cover the pot cover to minimize the contact area with oxygen and reduce oxidation. And the heating time of boiling water is shorter than that of cold water, and the oxidation is slightly less; Cooking in pressure cooker has less contact with oxygen, which is beneficial to the maintenance of soup color. However, as long as the soup is scooped out, it will soon change color.

At the same time, pay attention to cooking time. When cooking mung bean soup every day, it is difficult for them to keep yellow-green because of too long cooking time and full contact with oxygen. You've been cooking for two hours, which is too long. I suggest you soak it in water first. Someone taught me a quick way to soften mung beans, that is, put them in a thermos cup, heat them for two or three hours, and cover them. The zoom of your soup is probably because the mung bean is cooked for too long and sticks to the pot.