Is the pork stamp special? Can it be washed off once it is stamped?

Review expert: Wang Guoyi, Postdoctoral Fellow in Nutrition and Food Safety, China Agricultural University

Pork, as an important meat food in daily life, is often found with blue-purple stamps with words like "quarantine passed and slaughter allowed" on it when purchased. These stamps are quite stubborn and will remain on the pig skin even when the pork is cooked.

A few days ago, there was a short video about the quarantine stamp: the protagonist of the video was a boy who put the quarantine stamp on his face as a "punishment" after losing a game with his friends. However, he found that the stamp on his face could not be washed off!

According to the author, he rubbed his face until it was "almost on fire" from November 28th to 30th, but was unable to remove the stains.

Source: A short video platform

Some netizens commented: "You can try testing concealer (a cosmetic used to cover facial blemishes)" and "How come the tattoo is so distinctive?" These interesting comments, combined with the embarrassing look of the video blogger, make the video extremely funny.

So, can the stamp on the blogger's face be washed off in the end? Let's study this quarantine stamp together today.

Why does pork need to be stamped?

The stamp on pork refers to the stamp with production, quarantine certification and other marks on the pork. It plays a very important role in protecting the rights and interests of consumers and food safety.

The relevant regulations, the "Regulations on the Management of Pig Slaughter", were promulgated by the State Council as early as 1997 and were revised for the fourth time in 2021. The regulations clearly stipulate that pigs slaughtered by designated pig slaughterhouses (farms) must be inspected and quarantined by animal health supervision agencies in accordance with the law, and a quarantine certificate must be attached. Only pork that has passed the inspection can be stamped with the meat quality inspection pass stamp or the meat quality inspection pass mark. This mark represents that the pork sold has been inspected and approved by relevant departments, meets food safety standards, and is allowed to be put on the shelves for sale and supplied to the public.

Source of relevant documents and regulations: China Government Network

At the same time, stamping means that consumers can better identify the source and quality of pork through the stamps on the pork, and can choose high-quality and safe meat products with more confidence. It not only improves consumers' sense of purchase security, but also standardizes the production process and ensures the quality and safety of pork.

Through the seal, consumers can learn about the production date, production location, breeding methods and other information of the pork. At the same time, they can also easily trace the source of the pork, which plays an important role in supervising food safety.

What’s special about the ink used in seals?

These pork stamps are so stubborn and difficult to remove. The reason is that the ink used in the stamps is quite different from traditional ink pads. Traditional ink pads are mostly made of pigments and adhesives, and sometimes some waterproofing agents are added. Even with the addition of waterproofing agents, the waterproof performance of ordinary ink pads is still not strong enough and can be easily diluted by water. In this way, the text or pattern printed on the pork can be easily washed off, and the information about the pork may be tampered with, which will not play a role in protecting consumer rights and food safety.

In order to overcome this problem, the ink composition of pork seals adopts a mixture of dyes and solvents . The dyes mostly use methyl violet or acid fuchsin, food pigments (such as food blue, food red), etc., and the solvents mostly use glycerin, edible alcohol and water. The materials and concentrations of seal formulas in different regions are not the same.

Methyl violet source: Wikipedia/GOKLuLe

In the past, pork stamps in my country used a biological dye called "gentian violet". Gentian violet is also called methyl violet. After dilution, it becomes gentian violet, which is a commonly used external medicine. Gentian violet has a certain affinity with chromosome DNA. The two can combine to make chromosomes appear purple, which can color pork and is not easy to wash off. Due to this characteristic, gentian violet staining is also widely used in genetics, cell biology and other fields.

Later, a British pharmacologist applied gentian violet to the skin of mice, and the experiment proved that gentian violet was carcinogenic. Therefore, in order to ensure the safety of the people's tongue, the formula of pork seal ink removed gentian violet and no longer used it. The raw materials of seals were gradually replaced by food-grade raw materials, such as beetroot red, carmine and other edible pigments to replace "gentian violet", and white wine could also replace alcohol.

The most commonly used dye at present is the food blue quarantine marking liquid , which is mainly made by mixing and dissolving substances such as brilliant blue, glycerin and vitamin C.

Can the stamp be washed off?

The reason why the stamp on pork is so durable is that the pig has been slaughtered, its epidermal cells have lost their vitality and no longer have the basic metabolic function. The pigment has entered the cells, and the pigment inside the cells will not disappear. As more and more pigment gradually penetrates into the pig skin, the stamp on the pork is stamped. Therefore, the stamp on the pork will not disappear and is difficult to wash off.

Source: News Photo

Some chefs will use liquor to treat these seals, using the principle of "like dissolves like" to clean the seals. Hydrogen peroxide can also be used, but it has strong oxidizing properties. When using it to treat pork, you need to be careful not to use too high a concentration to avoid causing harm to the human body. After treatment, rinse with plenty of water to remove the liquor, hydrogen peroxide and seal ink components remaining on the surface of the pork.

If the human body is accidentally stained with dye, you can also refer to the above method to minimize the traces of dye. But the guy at the beginning of the article, his skin has been penetrated by these pigments and cannot be completely washed off, so the only way to make the mark disappear completely is through the metabolism of human cells.

You can now buy similar stamps for entertainment purposes on online shopping platforms, but now that you know that quarantine stamp dyes are not to be trifled with, remember not to use them on yourself for fun in the future!