How is it that zongzi leaves are green after being cooked?
Dong Jinshi, an expert in food safety and environmental chemistry and secretary-general of the International Food Packaging Association, said that the zongzi leaves on the market are divided into dry zongzi leaves and fresh-keeping zongzi leaves. Dry leaves are yellow-green, and fresh leaves are bright green. There are two main reasons why the leaves of fresh-keeping zongzi can remain bright green. One is to add preservatives (preservatives); In addition, industrial copper sulfate and industrial copper chloride are added to soak the leaves. The zongzi leaves bought by Ms. Li are probably "green" zongzi leaves, which are harmful to human body. It is best not to eat them.
Fresh zongzi leaves are cooked at high temperature in the production process, and the color of zongzi leaves will be dark green, grayish black or light yellow, and there will never be turquoise zongzi leaves. In order to keep the leaves fresh and beautiful, some merchants use chemical dyeing method to add industrial copper sulfate and industrial copper chloride when soaking the leaves, so that the leaves that have lost their primary colors turn green, making their surfaces bright and their colors bright green. Excessive or long-term intake of copper by human body will cause a large amount of copper to accumulate in the liver, causing copper poisoning. This symptom is not easy to detect, once it appears, it may cause cancer and even endanger life.
The leaves of zongzi are green when cooked. Can you eat them?
No matter what kind of zongzi products are used, frozen zongzi, vacuum zongzi and cooked zongzi sold in the market rarely use fresh zongzi leaves, because the annual consumption peak season of zongzi is around the Dragon Boat Festival, and the picking season of zongzi leaves is usually in July-10 every year. Due to the influence of geography, preservation and transportation, there is no way to ensure that the green of fresh zongzi leaves will remain unchanged for a long time. In addition, zongzi must be cooked at high temperature before being sold, so the color of zongzi leaves can never be kept bright green.
How to distinguish zongzi leaves
When buying zongzi, don't covet bright green. Although the color of traditional air-dried zongzi leaves is old and dim, it is more natural and safe. In addition, it is best to buy zongzi that has been sealed and packaged by regular manufacturers. Recognition method of "seeing, smelling and distinguishing"
1, look at the appearance. The "turning green palm leaves" are green and even, and look beautiful; While the primary leaves are dark yellow.
2. smell it. Jiaozi wrapped in "green leaves" is not fragrant enough after cooking, and some of them will have a faint smell of sulfur.
3. Distinguish boiling water. After chemical treatment, the color of "turning green palm leaves" is relatively stable. The heated boiled water will appear pale green. If the green color is obvious, it means that the content of chemical raw materials is high. However, the boiled water of zongzi made of primary color zongzi leaves will appear pale yellow.