One reason is enough to persuade you to eat more lotus root!

In autumn in my country, lotus roots are very popular. Some have a sweet and crispy taste, some have a soft and sticky taste, and some are somewhere in between. Fried lotus root boxes, lotus root and pork ribs soup, fried lotus root, cold lotus root slices, glutinous rice lotus root, etc. are all commonly eaten. Are you drooling?

As the saying goes, "Lotus is full of treasures, and autumn lotus root is the most nutritious." Now is the season for eating lotus root, so you can't miss it. Eat more while the "lotus root" is available.

How nutritious is lotus root?

Lotus root has a history of more than 3,000 years of cultivation in my country. It is the rhizome of lotus in the soil and is a common aquatic vegetable. It is known as the "Eight Water Immortals" along with water bamboo, water chestnut, Euryale ferox, water celery, water shield, arrowhead and water chestnut. Lotus root mainly contains carbohydrates, dietary fiber, protein, vitamin C and mineral potassium.

▲Photo: Cross section of lotus root

1

carbohydrate

The carbohydrate content of lotus root is 11.5g/100g. [1] Although it is lower than that of potatoes and sweet potatoes, it is higher than most vegetables we eat. The starch content of different varieties of lotus root varies. Some lotus roots, such as the lotus root from Huai'an, Jiangsu, have a starch content of only 1.3g/100g, while the starch content of the lotus root from Honghe, Yunnan is 13.7g/100g. [2]

Therefore, some lotus roots with a soft and sticky texture are not suitable for eating as vegetables. If you like to eat lotus roots but want to take your weight into consideration, it is recommended to eat less rice.

2

Dietary fiber

According to data from the Chinese Food Composition Table, the insoluble dietary fiber content of lotus root is 2.2g/100g, which is twice that of potatoes. The dietary fiber content of different lotus root varieties also varies. Studies have shown that the total dietary fiber content of lotus root from Heze, Shandong Province is the highest, at about 7g/100g. [2]

3

Mineral Potassium

The potassium content of lotus root is 293 mg/100 g,[1] and the potassium content of lotus root from Yunnan Red River can reach 407 mg/100 g,[2] which is 1.6 times that of banana.

4

Vitamin C

Most lotus roots have a high vitamin C content. A study compared the nutritional components of lotus roots from 10 production areas and found that the vitamin C content of lotus roots ranged from 50% to 70%. The vitamin C content of lotus roots from Huai'an, Jiangsu, Jingzhou, Hubei, and Heze, Shandong were relatively high, at around 68 mg/100 g [2]. This content is higher than that of oranges and kiwis.

However, cooking will cause some loss of vitamin C. The retention rates under boiling, steaming, frying, and microwaving are 61.35%, 93.91%, 76.56%, and 85.87%, respectively. [3] From the data, except for boiling, other cooking methods do not cause much loss, which is still very helpful for our daily vitamin C supplementation.

5

protein

Lotus root has the highest protein content among vegetables. The protein content of lotus root from Jingzhou, Hubei Province is as high as 3.8g/100g, [1] which is higher than most vegetables. However, lotus root lacks methionine and isoleucine in its amino acid nutrition evaluation. Therefore, when eating lotus root, it is best to eat it with seaweed and beans to improve the absorption and utilization rate of protein. [2]

In addition, lotus root also contains antioxidants and calcium, zinc, iron and selenium.

As for the lotus root starch that is commonly eaten, it mainly refers to pure starch extracted from lotus roots, which contains a certain amount of resistant starch. [4] When mixed with warm water, it will form a gel state, which has a strong sense of fullness and a GI value of only 33. [1] It is a low-GI food and can be eaten even by diabetics.

What are the health benefits of eating lotus root regularly?

Lotus root is so nutritious, friends who love to eat lotus root can make arrangements! A lotus root the size of a palm is about 200 grams, and eating a lotus root the size of a fist is about 100 grams! What are the benefits of eating more lotus root?

▲Photo: 1 lotus root weighs about 200 grams

▲Photo: 1 fist of lotus root weighs about 100 grams

1

Helps lose weight and prevents constipation

Lotus root has very low calories, only 47kcal/100g, which is lower than sweet potatoes, potatoes, and yam. It is also rich in dietary fiber. Eating 100 grams of lotus root from Heze, Shandong can meet 28% of the minimum dietary fiber requirement of the general population. It not only has a strong sense of fullness and helps control appetite, but also promotes gastrointestinal motility and prevents constipation. Therefore, eating lotus root correctly can really make you "slim"!

2

Stabilize blood pressure

If you can eat 100 grams of Yunnan Red River lotus root every day, you can meet 20% of the general population's daily potassium needs, which is very helpful for controlling blood pressure.

3

Enhance immunity

The rich vitamin C in lotus root can promote the production of antibodies, enhance body resistance, and also help maintain skin health. Eating 100 grams of lotus root can meet nearly 50% of the general population's vitamin C requirement.

4

Antioxidant

Lotus roots are also rich in antioxidants, such as flavonoids and polyphenols, which help to remove excess free radicals from the body and have anti-inflammatory effects. The total flavonoid content of lotus roots from Meishan, Sichuan is high, nearly five times that of lotus roots from Huai'an, Jiangsu; the total polyphenol content of lotus roots from Honghe, Yunnan is high, nearly four times that of lotus roots from Huai'an, Jiangsu. [2]

Does lotus root contain excessive heavy metals?

Due to the rapid development of industry, agriculture and tourism, the discharge of "three wastes" has caused a large amount of pollutants such as heavy metals to be discharged into rivers and lakes, causing water pollution. Lotus root is an aquatic plant, so many people worry about whether the lotus root sold on the market contains excessive heavy metals, fearing that eating it will harm their health.

In response to this issue, some researchers have conducted random inspections on lotus roots on the market, which can be used as a reference for us.

Someone collected 16 batches of lotus roots from supermarkets and farmers’ markets in a certain city and tested and analyzed their heavy metal content. The results showed that heavy metals were detected in all batches of lotus roots to varying degrees, but all were within the standard limit values ​​of GB2762-2017 "National Food Safety Standard Limits of Contaminants in Food". [5]

For adults, this level of risk is acceptable, but there are certain health risks for children, so children are reminded to reduce the amount and frequency of eating lotus root.

Someone evaluated the characteristics of heavy metal content and health risks in lotus roots sold in Baoding. A total of 13 lotus root samples from different supermarkets were collected. The results showed that the lead, arsenic and arsenic in the lotus root samples exceeded the standard to varying degrees, reaching the level of light pollution. The average heavy metal content was as follows: lotus root nodes > lotus root skin > lotus root flesh. [6]

Although there are no obvious health hazards at present, researchers still recommend removing the lotus root skin and nodes when eating lotus root and only eating the lotus root flesh.

Lotus root drawing and color change

What's going on?

1

Why is it that “the lotus roots are still connected”?

There is an idiom called "藕断丝连", which comes from lotus root.

▲Photo: Lotus root drawing

After the lotus root is broken, there will be a phenomenon of broken threads connected. The threading of lotus root is different from that of yam. The threading of yam is caused by mucus, but the threading of lotus root is not mucus, but the duct wall (annular duct wall) of the spiral duct in the internal transport tissue of the lotus root. When the lotus root is broken, the duct wall will be stretched like a spring.

If you look closely, you will find that this "lotus root drawing" is thread-like, and to the naked eye it looks more like a "wavy line" rather than a "straight line".

2

Why does lotus root change color?

Friends who often eat lotus root will have the experience that lotus root is a "color change king". It will turn black after being cut and turn red when boiled in soup. Why is this?

The lotus root turns black after being cut because it contains phenolic substances. After being cut, it will undergo enzymatic browning when it comes into contact with enzymes and oxygen. The quinones produced in this process will polymerize into colored substances, causing the surface of the cut lotus root to gradually turn brown. The longer it is left, the darker the color will be, and eventually it will turn black.

If you cannot cook it immediately after cutting, soak it in clean water as soon as possible. Isolating the oxygen will prevent the oxidation reaction and maintain the color of the lotus root. But don't leave it for too long, or it will deteriorate.

It is normal for the soup to turn red when cooked. This is because lotus root contains proanthocyanidins,[7] which are also a type of phenolic substance. After being treated at high temperatures, they will be oxidized into anthocyanins and then turn red.

▲Photo: Lotus root bone soup

How to store lotus root?

If the purchased lotus root is not stored properly, it will easily turn brown, lose its hardness, and have a bad taste. Storage temperature is a key factor affecting the quality of food. Low-temperature storage can effectively regulate the physiological activities of fruits and vegetables, reduce the speed of various physiological and biochemical reactions, and delay the decline of fruit and vegetable quality.

If the purchased lotus root only needs to be stored for a short period of time, it can be soaked in cold water and refrigerated. If it needs to be stored for a long time, within the storage period of 10 weeks, it is recommended to store it at -1°C, which can better maintain the appearance quality and higher flesh hardness of the lotus root, and also delay the browning of the lotus root. [8]

Summarize:

Don't worry, eating lotus root won't make you ugly! Start eating it this fall. It should be noted that aquatic plants like lotus root cannot be eaten raw, as they may be contaminated by bacteria and parasites. Even lotus root slices should be blanched first!

References

[1] Yang Yuexin. Chinese Food Composition Table 6th Edition Volume 1[M]. Peking University Medical Press, 2018

[2] Cheng Tingting, Hui Xiaohan, Shang Xinxin, et al. Nutritional composition analysis and comprehensive quality evaluation of lotus roots from 10 origins[J]. Food Industry Science and Technology, 2021, 42(08): 320-325. DOI: 10.13386/j.issn1002-0306.2020060110.

[3] Chen Ting. Effects of cooking and ultra-high pressure treatment on the edible quality of lotus root[D]. Yangzhou University, 2015.

[4] Liu Youjin. Research on the processing technology of high-resistant starch instant whole lotus root powder[D]. Fujian Agriculture and Forestry University, 2018.

[5] Liu Yuling. Detection of heavy metal content in lotus root and health risk assessment[J]. Food Engineering, 2022(3):69-72

[6] Gao Peipei, Xiao Bing, Liu Wenju, Zhang Xiangyu, Dong Junwen, Xue Peiying. Characteristics of heavy metal content in lotus root and its health risk assessment[J]. Environmental Chemistry, 2020, 0(2): 362-370

[7] Liu Tengfei, Lu Haoqian, Li Jun, et al. Research progress of proanthocyanidins in lotus[J]. Food and Fermentation Industries, 2022, 48(12): 307-315. DOI: 10.13995/j.cnki.11-1802/ts.028685.

[8] Chen Jinhui, Qi Xin, Yi Yang, et al. Ice temperature storage delays the quality deterioration of lotus root[J]. Modern Food Science and Technology, 2022, 38(06): 136-144. DOI: 10.13982/j.mfst.1673-9078.2022.6.1021.

Author: Xue Qingxin Member of Chinese Nutrition Society Registered Nutritionist Health Manager Public Nutritionist

Review | Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center