Is peeling off the skin of the grape skin? Experts say no basis

Autumn harvest, a variety of colorful fruits will also be listed one after another, Qingfei moistening autumn pear, nourishing heat of sugar cane, as well as detoxification of the grapes.

On the other hand, yesterday's news that “the market discovered genetically modified grapes” sparked heated discussions. A grape called “beautiful person” was transmitted as a genetically modified variety, because the peeled skin does not oxidize and turn black. This has caused many people to panic.

Is this argument justified? Yesterday, the Beijing News reporter visited several fruit shops in Chaoyang District and purchased four kinds of grapes, one green one and four kinds of apples. The experiment found that after peeling the skin for two hours, the surface color of the four grape skins and the green peels did not change significantly, while the color of the apple surface gradually turned yellow.

Huang Dazhao, a researcher at the Institute of Biotechnology of the Chinese Academy of Agricultural Sciences, said that there are currently no genetically modified grape varieties in China, and it is unreliable to verify the genetic modification by peeling and looking at the color change of the grape skin.

Explanation 1

There is no GM grape variety in China

For the statement that the "Beauty Man" grape on the Internet is a genetically modified variety, Huang Dazhao, a researcher at the Institute of Biotechnology of the Chinese Academy of Agricultural Sciences, said that so far, there is no GM grape variety in China.

Huang Dazhao introduced that the Ministry of Agriculture had previously issued the current domestic types of genetically modified crops and genetically modified products, which did not include grape varieties. Therefore, there is also no possibility that imported genetically modified grapes exist in the domestic market. The practice of verifying genetically modified grapes transmitted on the Internet is also unfounded.

Huang Daxuan made it clear that the method of distinguishing transgenes based on changes in the appearance or color of the skin after peeling is not scientifically sound and does not fly.

The reporter learned that according to the "Administrative Measures on the Labeling of Agricultural Genetically Modified Organisms", currently 17 categories of saleable genetically modified organisms other than papayas have been listed in the catalog of genetically modified markers.

However, inclusion of the catalogue does not mean that the product must have entered the Chinese market. Huang Dazhao said that although China has approved the import of genetically modified tomatoes, it is required to be marked out if it enters China. However, in reality, the product has not entered the Chinese market, nor has it been commercialized in China.

Doubt 2

Different levels of enzymes cause varying degrees of discoloration

In the experiment, the change in color of the grapes was not apparent to the apple. According to Zhu Yi, an associate professor of food safety at China Agricultural University, the apple contains a protein called polyphenol oxidase. It catalyzes the oxidation of phenolic substances in apples, making them yellow or brown.

She said that after cutting or tearing the epidermis, the cells will rupture, and the polyphenol oxidase and phenolic substances will come together and oxidize the phenolic compounds into quinones. The corresponding parts will produce color changes.

Due to the different color of the skin of different fruits, the identification of color changes will be different for the naked eye. In other words, perhaps the color of the grape's surface has also changed, but it is not seen. She said that most of the polyphenol oxidases in grapes are concentrated in fruit stems, and the content of pulp is relatively small, which may also be a reason for the inconspicuous color change.

Regarding the rumors of "beautiful people", the grape skin has no oxidative discoloration for 3 hours. Fan Zhihong, associate professor of the College of Food Nutrition and Food Health, China Agricultural University, said that the skin contains polyphenol oxidase, but the content of enzymes in each variety Differently, it will naturally lead to different degrees of color change.

In addition, the content of phenols and the acidity of different varieties of fruit peels are also different, and they all lead to different degrees of oxidation reactions, and the color changes are naturally different.

Many people think that after the fruit is oxidized, it is unfit for human consumption. According to Zhu Yi, oxidation only reduces the vitamin C content in fruits, and consumption does not cause harm to the human body.

experiment

After five hours, the color of the four grape skins is not obvious

According to rumors on the Internet, the grape named “Beauty Finger” is an illegal genetically modified fruit.

It is rumored that after the original non-transgenic fruit was cut open and encountered air, the enzyme in the fruit would be oxidized and discolored. After the domestic non-genetically modified grape peeled off the skin, the grape skin would be oxidized and changed black. Beauty means that the grapes are peeled for 3 hours without oxidative discoloration. This is because the “beauty man” uses genetically modified technology to remove enzymes and prevent fruit from oxidizing.

In order to verify whether or not the rumors are credible, the reporter went to several supermarkets and fruit shops yesterday and bought four kinds of grapes and one kind of green tea. The grape types were "Beauty Man", Turpan Seedless, Kyoho and Muscat, and 4 Apples, namely imported snake fruit, green apple and two kinds of domestic Fuji apple.

Then, according to the rumors, the reporter stripped the grapes and grapes, cut the apples in half and placed them in the air.

● Two hours later:

Changes in the color of the skin and flesh of the four grapes and greens were not obvious. The "beautiful man" refers to a relatively large change in the relative color of the flesh, the color gradually becomes yellowish, and a liquid appears around the rose-flavored grape.

The four types of apple cut surface gradually turned yellow from the original color, and it was filamentous. Among them, the yellow color of two kinds of Fuji apples has changed obviously. The half of the surface of the snake fruit is relatively obvious, and the change of the green apple is the least obvious.

● After five hours:

The color change of the skin and flesh of the four grapes and grapefruit is still small, and the "beautiful man" refers to a relatively obvious change in the flesh, which gradually turns yellow, and the liquid around the rose grape grows.

The yellow surface of the apple gradually darkens, develops brownish, and the coverage area becomes larger. In contrast, the changes of the two types of Red Fuji are still the most obvious.

Figures 1 and 2 show the comparison of four grapes and green grapes just peeled and peeled five hours later. The top left is the Kyoho grape, the left middle is the green one, the bottom left is the Turpan seedless grape, the upper right is the rose incense, and the lower right is the “beautiful person”.

Figures 3 and 4 show the comparison of four types of apples after they have been cut and cut for five hours. The upper left is the snake fruit, the upper right is the green apple, and the lower two are the Fuji apple.

â–  Rumors about genetic modification

At the beginning of coding 4 is the transgene?

There are rumors that the Arabic numerals on the imported fruit labeling code have hidden mystery, and the 4 characters at the beginning are mostly genetically modified fruits. In addition, the beginning of the 3 word indicates that the sprayed pesticide, the beginning of the 5 word, is a hybrid fruit.

The imported grapes and apples imported by the reporter yesterday were also the beginning of four characters. Is there 4 genetically modified fruit?

According to an industry person involved in fruit trading, the label attached to imported fruits is called PLU code, and the overall representation of varieties and production areas is not unique. Therefore, users are not accurate.

Isn't black potatoes a genetically modified product?

It is understood that the darkening of potatoes stems from the fact that the polyphenols contained in the potatoes are oxidized by polyphenol oxidase in oxygen to produce browning.

Huang Dazhao, a researcher at the Institute of Biotechnology of the Chinese Academy of Agricultural Sciences, said that, for example, potato peeling does not turn black, which is not a characteristic of genetically modified potatoes, and China does not produce genetically modified potatoes.

According to a scientific study, potato varieties that did not brown easily were cultivated through traditional breeding as early as 1995. The two genetically modified potatoes that have been approved to be put on the market worldwide are not designed to prevent browning, and their current planting area is also close to zero.

Plants do not move insects is genetically modified?

It is understood that insect resistance is one of the major traits of transgenic plants.

According to relevant experts, the insect-resistant protein gene Bt has been introduced into large-scale planted insect-resistant cotton in China. However, it is only targeted at lepidopteran insect pests such as cotton bollworm. It is also harmed by insects such as blind borers and red spiders. It still needs chemistry. Pesticide control. You can't judge whether you want to transgeneize if the pests like to visit.

Source: Beijing News

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