Schrödinger's mung bean soup: red or green?

Mung beans have a long history in my country, and we have developed a variety of ways to eat them. They can be made into bean porridge, bean rice, bean wine, and bean cakes. The sprouted mung beans can be used to cook dishes and can even be used as feed for cattle and horses. Even Li Shizhen lamented that it is "an essential food, a top-notch vegetable, and a good grain to save the world" [Compendium of Materia Medica].

From a long time ago, it has been synonymous with "relieving summer heat and thirst, clearing away heat and detoxifying" in the hearts of Chinese people. As a traditional food ingredient with both medicinal and edible properties, what is its nutritional value from a modern perspective?

01 Nutritional value of mung beans

Beans are divided into soybeans and miscellaneous beans. Soybeans include yellow beans, black beans, and green beans. Others are miscellaneous beans , including mung beans, red beans, kidney beans, and flower beans.

As a miscellaneous legume food, mung bean has three highs and two lows: high starch, high protein, high fiber, low fat and low GI.

Although high in starch, it has a low GI

Because a large part of mung bean starch is resistant starch , which can be regarded as insoluble dietary fiber, coupled with the interference of the high protein content in mung beans, the starch in mung beans is not as easily digested and absorbed as cereal starch, so it is a low GI food and is also very friendly to diabetic patients.

Another characteristic of mung bean starch is that it is mostly straight-chain starch and is easy to age, so it is easy to process into special snacks such as vermicelli, rice noodles, and rice paper.

High in protein and lysine

The protein content of mung bean is over 20% and it is rich in lysine.

Lysine is an essential amino acid that is lacking in cereal foods, and the lysine content in mung beans reaches 1626mg/100g , which is more than 6 times that of rice. However, sulfur-containing amino acids (methionine + cysteine) are relatively lacking. Therefore, mung beans can be called the golden partner of staple grains. If mung beans are cooked with rice, protein complementation can be achieved and protein utilization can be improved.

High in fiber

The content of insoluble dietary fiber in mung bean is 6.4g/100g , which is mainly concentrated in the seed coat.

Low in fat, but high in fat-soluble vitamins

The content of VE and VA in mung beans is not low, which is dozens of times higher than that of grain raw materials such as rice and wheat.

In addition, mung beans are also rich in B vitamins, and minerals such as potassium and magnesium, which are nutrients that are relatively lacking in refined rice and wheat.

Nutritional content of mung beans/100g edible part | [2]

Rich in bioactive substances

Mung beans also contain many biologically active substances, such as polyphenols (flavonoids), polysaccharides, coumarins, phytosterols , etc., which play an important role in many aspects such as auxiliary antioxidant and lipid-lowering [3, 4].

As a kind of legume, mung bean is very suitable for eating with staple food. It can provide balanced nutrition such as dietary fiber, vitamin B, potassium, magnesium, etc., and make up for the deficiency of over-processed cereals. The latest version of China's dietary guidelines also proposes that ensuring adequate intake of whole grains and legumes is conducive to reducing the risk of overweight/obesity, type 2 diabetes, cardiovascular disease, etc. It also recommends that adults eat 200-300g of cereals per day, including 50-150g of whole grains and legumes [4].

Recommended intake of cereals and tubers for different groups of people | [5]

02 Is mung bean soup red or green?

Mung bean soup is a popular drink for cooling down in the hot summer.

Some people cook mung bean soup and find that even if the mung beans are from the same bag, the soup is sometimes green and sometimes red.

In fact, the color of mung bean soup depends on the polyphenols in mung beans. One of the characteristics of polyphenols is anti-oxidation. When heated at high temperature and exposed to oxygen in the air, they will be oxidized into quinones, etc., and the mung bean soup will turn red, and the polyphenols at this time will also lose their antioxidant effect.

To preserve the antioxidant effect of polyphenols and keep mung bean soup green, there are several tips:

① You can choose purified water. Alkaline water will cause the mung bean soup to turn red and reduce its antioxidant capacity. If it is tap water, especially tap water in northern my country, which is weakly alkaline, the mung bean soup will change color quickly. In addition, the metal ions in tap water will chelate with polyphenols and reduce antioxidant capacity. Alternatively, you can try adding a little white vinegar or a few drops of lemon juice to the tap water. Without affecting the taste, you can try to keep the soup green.

② Do not use metal pots such as iron pots. You can choose stainless steel pots, casseroles, etc. The reason is the same as above [6].

③ Cover the lid when cooking to reduce the chance of contact with air, and the cooking time should not exceed 1 hour.

03 Besides cooking into soup, what other magical ways are there to eat mung beans?

1. Low-calorie mung bean ice cream

Chocolate cream is too sweet, so use low-calorie mung beans instead.

No cream, no sugar, just milk sweetener will do.

The simplest way is to mix the cooked mung beans with milk. If you like a sweet taste, you can add a little bit of sweetener, and then put it directly into the mold and freeze it into shape.

2. Mung Bean Smoothie Latte

You must have never tried eating mung beans in this way.

All you need is mung bean slush, skim milk, and espresso, and you have a cup of beautiful and healthy mung bean frappé latte! A mouthful of sandy and smooth, a mouthful of silky, enjoy a multi-layered summer taste experience.

3. Mung Bean Milk

Unlock another combination of milk and mung bean paste.

Take half of the cooked mung beans, add milk to make mung bean paste, and mix it with the other half of the mung beans. You will have a thirst-quenching afternoon tea that is essential for the dog days of summer!

4. Mung Bean Ice Cream

There are many ways to make mung bean cake. In fact, the main thing is to shape the mung bean paste. You can use a mold to make it into your favorite shape. You can also choose to add other small ingredients and sugar, or use sweeteners. Don't miss this home-made healthy and delicious snack!

Finally, a reminder: one of the principles of cooking mung beans is to "eat dry and squeeze out everything": if possible, do not peel them, and if possible, keep the whole grains, keep them whole. This way, you can fully utilize all the nutrients of the mung beans.

References:

[1] Compendium of Materia Medica.

[2] Chinese food composition table.

[3] Zhang Ting et al. Research progress on classification, nutritional efficacy and product development of miscellaneous beans[J]. Food Industry Science and Technology, 2023, 44(04): 428-437.

[4] Zhou Sumei et al. Nutritional functional characteristics of mung bean and its application in the development of plant-based foods[J]. Cereals, Oils and Food Science and Technology, 2022, 30(02):16-23+12.

[5] Dietary Guidelines for Chinese Residents (2022).

[6] Chen Ran et al. Effects of pH value and metal ions in cooking water on mung bean broth[J]. Food Science, 2014, 35(03): 96-99.