Because the active ingredients of mung bean for heatstroke prevention may mainly be polyphenol antioxidants, it is very important to maintain its activity for the heatstroke prevention effect of mung bean.
★ What's the difference between green and red soup in terms of health care effect? Through the determination of antioxidant properties, it is found that the ability of mung bean soup to scavenge free radicals has a great relationship with color. The effect of green mung bean soup is much better, while that of discolored mung bean soup is obviously worse.
Data analysis shows that there is a significant correlation between the color of bean soup and its antioxidant activity. Adding a small amount of salt and citric acid is beneficial to improve the antioxidant effect, while adding alkali cooking will greatly reduce the antioxidant effect.
Mung bean is rich in B vitamins, which is an important part of mung bean's summer-heat relieving characteristics and can make up for the nutritional loss when sweating. Alkali can seriously destroy many B vitamins. At the same time, the flavonoids in mung beans will also be lost due to alkali addition, and the structure will change and the color will turn yellow. Therefore, it is best not to add alkali to cook mung bean porridge. If you want to make porridge sticky, consider adding a small amount of oatmeal or glutinous rice to "thicken".
▲ Tips for preventing discoloration of mung bean soup
1, boil with purified water.
So, will boiled mung bean soup turn red? Actually, it is not. Experiments we have done have proved that mung bean soup can be preserved for a long time without discoloration, and the secret of the problem lies in the different water used to cook beans.
The mung bean soup was boiled with tap water, mineral water, purified water and deionized water respectively. The result showed that the color of deionized water was the greenest and remained unchanged for a long time. The color of mung bean soup boiled in tap water changes the fastest, and it darkens obviously almost every minute after touching the air, and soon turns red. It is obviously caused by different water quality.
We adjusted the tap water to different pH values to cook mung bean soup, and found that the pH value can greatly affect the discoloration effect of the soup. Acidic tap water rarely changes color after boiling, while slightly alkaline tap water changes color very quickly after boiling. Tap water in the north is mostly alkaline water, so the color of the boiled mung bean soup is particularly fast, and obvious color changes can be seen within two minutes. But for deionized water, no matter what pH value, the discoloration is very small.
In this way, a simple method of boiling mung bean soup without discoloration is obtained-boiling it directly with pure water, no problem.
Step 2 add vinegar when cooking
If there is no pure water at home, it is not impossible to keep green by boiling mung bean soup with tap water. When cooking mung bean soup, just add half a spoonful of white vinegar or squeeze half a spoonful of lemon juice to keep the green of mung bean soup in the air for a long time.
The key is not to add too much, let alone make the water sour, just adjust pH 6.
When cooking, it is best to adjust the water first, and then cook the mung bean clear soup, so it is not easy to change color. Even if it is stored for half an hour, it can still keep beautiful green.
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 might as well take out the soup cooked in 10 minutes and drink it as soon as possible, because the color of the bean soup at this time is bright green, and the dissolved substances are mainly the active ingredients in the bean skin, with the lowest oxidation degree and the strongest heat-clearing ability.
Don't throw away the remaining mung beans after taking out these soups. You can add boiling water to cook them into green bean paste, or you can add rice to cook them into mung bean porridge.
◆ Do you want to add honey or sugar to the cooked mung bean soup?
If you add a lot of honey to mung bean soup, the soup will turn black, because honey contains many minerals, including iron ions. These metal ions often form "complexes" with polyphenols, and the colors are sauce color, black, brown, dark green and so on. This makes the soup black and black. This is a normal phenomenon, non-toxic and harmless.
But this may affect the absorption of trace minerals in honey, but because of the small amount, it does not hinder the overall dietary nutrition.
In addition, putting a lot of sugar or honey in the cooking process will prevent water from infiltrating into beans and affect the gelatinization process of starch. Sugar and honey are both ingredients of love the water. On the one hand, they compete with starch for water, on the other hand, they prevent starch molecules from fully expanding in water. So if you add sugar, you should cook it for a while or raise the cooking temperature.
● Can I cook mung bean soup in an iron pot?
As we all know, traditional Chinese medicine can't be fried in an iron pan, and fruits can't be cooked in an iron pan. The reason is that iron can catalyze the oxidative decomposition of vitamins, and another reason is that it is worried that iron will react with effective components such as polyphenols in medicinal materials and fruits, thus affecting the efficacy or color. Use a casserole or ceramic pot, and you won't have these troubles. So is mung bean soup.
Flavonoids in mung bean skin may form a dark complex after interacting with metal ions. For example, adding honey to mung bean soup will produce a black color, which is completely the same reason.
Although no toxic substances are produced in this reaction, it may interfere with the antioxidant effect of mung beans and hinder the absorption of metal ions. Therefore, when cooking mung bean soup, it is most inappropriate to use an iron pot, but casserole is the most ideal.