When eating Zongzi during Dragon Boat Festival, please beware of this kind of Zongzi leaves

During the Dragon Boat Festival, eating zongzi is a must. Many friends prepared glutinous rice fillings, zong leaves and cotton threads in advance, ready to show their skills. We, Dad Review, also planned an activity to make zongzi, bought the materials early, and wanted to experience the fun of making zongzi with our team members.

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Who would have thought that the rice dumplings leaves bought online were suspected by a technical guy who studies food to be "green rice dumplings leaves".

1. What are green bamboo leaves? There are two common types of bamboo leaves for wrapping rice dumplings: dry and wet. We also often call wet bamboo leaves fresh bamboo leaves.

Fresh zong leaves are difficult to preserve, and old leaves will fade and dry up. Zongzi wrapped in dry zong leaves look worse than those wrapped in fresh leaves. So some merchants with "evil ideas" soaked dry zong leaves in copper sulfate to make them as green as fresh leaves. This is the "re-greening zong leaves" that we hope everyone will be wary of.

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Although copper is one of the elements needed by the human body, excessive intake can cause nausea and vomiting. Long-term and large-scale intake can also cause copper poisoning.

2. We conducted an experiment to authentically restore the production process of the green rice dumplings leaves.

Use clean water and water with copper sulfate added to boil and soak the dried rice dumplings leaves for 20 minutes respectively.

The effect is so obvious that the rice dumplings leaves with copper sulfate have turned back from yellow to green.

Then we boiled the two kinds of leaves separately. The dry leaves boiled in water remained yellow after boiling, and the soup turned light yellow; the green leaves boiled in water turned green after boiling.

At this time, if you take an iron product, such as a nail, stapler, paper clip, etc., and put it in the water of boiling green rice leaves, the iron and copper sulfate will undergo a replacement reaction, and copper will accumulate on the surface of the iron product and turn brown-black, like this.

In addition, real fresh zongzi leaves smell like grass, while green zongzi leaves smell like sulfur.

3. Testing the greening of zongzi leaves We bought 4 types of fresh zongzi leaves and 2 types of dried zongzi leaves for testing. The fresh zongzi leaves are all vacuum packed, green and moist, and have a strong smell when opened.

The test results are as follows:

The copper content of the four types of fresh rice dumplings leaves exceeded the "reasonable range". Who can accept this "increasing the quantity without increasing the price"?

4. Does the rice dumpling wrapped in green bamboo leaves contain copper?

After all, the leaves of the rice dumplings are not eaten, so will the rice dumplings be affected by the “green leaves”?

We wrapped 3 kinds of rice dumplings with green rice leaves and 1 kind of rice dumplings with dry rice leaves.

After the rice dumplings are cooked through, they are sent to the laboratory to test the copper content in the part of the glutinous rice that has been in contact with the rice leaves.

The test results are as follows:

The test found that there was almost no copper detected in the rice dumplings wrapped in dry rice leaves, but two types of rice dumplings wrapped in green rice leaves were found to contain 146 and 352 mg/kg of copper respectively, which shows that there is still an impact on consumption.

5. There are some rules for eating zongzi: 1. Eat in moderation

Although zongzi is delicious, you should not eat too much at one time.

Zongzi is mainly made of glutinous rice, and the fillings vary, including meat, egg yolk meat, candied dates, red bean paste, etc. The common specifications of zongzi on the market are 100g/1. Although the size is small, the calories are very high. Take the fresh meat zongzi of Wu F Zhai as an example.

981 kilojoules of energy is equivalent to 234 kilocalories. If you do some calculations, the calories of eating one rice dumpling are almost the same as eating two bowls of 2 liang of rice.

Zongzi is not big, and friends with a good appetite can probably eat 2 at a time, which is about the same as eating 4 bowls of rice. Looking at this calorie intake, don't always think about losing weight.

2. Eat with

When eating zongzi, zongzi is enough as the staple food. You can pair it with some cold dishes and a bowl of vegetable soup, such as winter melon soup, green vegetable soup, loofah soup, etc. It is delicious and healthy.

3. These 4 groups of people should be careful when eating zongzi

Cardiovascular disease patients

Animal fat is often added when processing zongzi, such as meat zongzi, lard bean paste zongzi, etc. People with high blood pressure, high blood lipids, and coronary heart disease should not eat more.

Diabetic patients

Diabetic patients or people with unstable blood sugar should be careful to eat less sweet rice dumplings, such as candied date rice dumplings, red bean paste rice dumplings, etc.

At the same time, other zongzi should not be eaten too much, because the main ingredient of zongzi is glutinous rice, and the GI value (glycemic index) of cooked glutinous rice is 87, which is a high GI food. The high glycemic index will accelerate the rise of blood sugar for people who already suffer from diabetes.

People with poor stomach

Zongzi is very sticky and difficult to digest. For people with poor digestive function, eating too much will increase the burden on the gastrointestinal tract.

Elderly and children

Zongzi is very sticky. If the elderly and children eat too much, it can easily cause indigestion and choking. Try to chew slowly when eating.

6. How to choose Zongzi Most brand packaged Zongzi are made of dry Zong leaves, so there will be no problem of copper sulfate soaking. Bulk Zongzi needs more attention.

When you buy zongzi leaves to wrap zongzi yourself, you must pay attention to whether the leaves are green. If you are not obsessed with appearance or a perfectionist, you can just buy dry zongzi leaves.

There are four aspects to consider when purchasing zongzi:

★ Look at the packaging label

Pay attention to the production date, shelf life, manufacturer, ingredient list and other information to avoid purchasing products without any certification. Be sure to check the shelf life carefully.

★ Check for leaks

Do not buy vacuum-packed rice dumplings that are damaged, leaking, or bulging.

★Look at the rope used to tie the zongzi

Choose natural materials such as cotton or straw ropes, and try to avoid nylon ropes.

★ Taste

If the rice dumpling tastes bitter or has any strange smell, such as rancid smell, do not eat it.

The problem of glutinous rice dumplings leaves turning green again has been around for years, and some rice dumplings have even been recalled because of it.

It is 2020 now, and the green zongzi leaves are still popular, and the health risks still exist. This year, we can only rely on our own attention. I hope that this situation will change when we test the zongzi leaves again next year.

Please eat Zongzi online, and wish everyone a wonderful holiday~

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References:

[1]http://epaper.xiancn.com/xawb/html/2008-06/05/content_42689.htm

[2]http://www.cqn.com.cn/pp/content/2018-06/28/content_5968646.htm

[3] State Administration for Market Regulation. Consumer tips for eating rice dumplings during the Dragon Boat Festival [EB/OL].

http://www.samr.gov.cn/spcjs/yjjl/spyj/201906/t20190605_302120.html, 2019-6-4.

[4] China Center for Disease Control and Prevention. Eating Zongzi should also be healthy [EB/OL].

http://www.chinacdc.cn/jkzt/yyhspws/zstd_1703/201301/t20130106_75102.html,2013-01-06.

[5] Yang Yuexin, Wang Guangya, Pan Xingchang. Chinese Food Composition Table Volume 1 (2nd Edition) [M]. Peking University Medical Press: Beijing, 2009: 8, 309.