cook green bean soup with casserole, do not iron pot cooking, iron pot will be the iron ions will oxidize and decompose the nutrients in the green beans, so that green bean soup discoloration, and the flavonoids in the mung beans, will be released with the iron pot with the metal ions into a colorful complex, so soup color, so to green bean soup does not change color to avoid the iron pot soup, casserole, or pressure cooker cooking So, to avoid using iron pot to cook soup, use casserole, or pressure cooker to cook.
2 method 2: use pure water to cook green bean soup
Research found that the color of green bean soup with deionized water, and long-term color, and use tap water to cook soup will be in contact with the air is almost every minute is significantly darker, and soon turned red, the pH of the water can affect the effect of soup discoloration, the more alkaline the water, the more obvious its effect of discoloration, so the conditions of friends, in order to avoid the color of green bean soup, the more the color of the water, the more obvious the effect of the color of the water, so, the more the color of the water, the more the color of the water, the more the color of the water, the more the color of the water. Condition of friends, in order to avoid mung bean soup discoloration can use pure water to cook mung beans.
3 Method 3: Add vinegar to cook
If you don't have pure water at home, and you want to keep the pure green green green bean soup, you can add some half a spoon of white vinegar, or half a spoonful of lemon juice when you cook green bean soup, so you can strengthen the antioxidant effect of the green bean soup in the air, delay the oxidation of polyphenols in the green beans to keep the color of the blue and green, but you should not add too much, to avoid the water becoming acidic.
4 Method 4: Reduce contact with the air
Because mung beans are difficult to cook, the general public will change the stirring side of the cooking, the pot cover will always be unveiled, which increases the contact area of mung beans and oxygen, in order to mung bean soup does not change color. Must reduce the contact between green beans and air, reduce oxidation, it is best to use boiling water to cook, so that you can reduce the heating time, shorten the opportunity to be oxidized, but also available in the pressure cooker to cook, so that you can reduce the oxygen contact surface. Beneficial to the maintenance of soup color, but this method can not make the color of green beans to maintain a long time.