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Recently, two videos claiming that laver is made of plastic bags circulated on the Internet. In the video, someone put laver into the water and pulled it open, saying that it is ductile, black and transparent, and it looks like a plastic bag, which determines that laver is made of black plastic bags.

Can plastic bags be made into laver? The reporter interviewed Ruan Guangfeng, director of the business department of Kexin Food and nutrition Information Exchange Center on the 22nd.

Ruan Guangfeng clearly pointed out that this is a rumor, the situation in the video can be explained by the characteristics of laver itself. "Laver appears to chew, bite not rotten, etc., may be because the temperature of the water in laver is not enough, the color is dark brown may be because the storage time is longer, normal laver itself is translucent after expansion. None of these can show that there are quality problems with laver, let alone support the idea of "plastic fake laver"."

As a kind of algae, lai is rich in polysaccharides such as gum, which makes it smooth and tough when it is harvested and dried.

"After encountering water, polysaccharide substances such as gum will combine with water molecules, and combine with polysaccharide molecules to form a relatively tight network structure. Just like a few people, holding hands together with the help of water molecules, they become very tough and difficult to tear, which is the gel characteristics of nori. But the size of this gel property depends on the temperature of the water. If the temperature is too high, the bond becomes loose, which is what we normally see in seaweed soup." Ruan explained that the toughness of laver is not easy to tear, and it is related to the water temperature of the laver, rather than "the plastic bag".

Ruan Guangfeng also pointed out that the cells of laver contain phycoerythrodin, which makes it appear different shades of purplish red when fresh. However, due to the rapid degradation rate of phycolubin, the general laver after processing, storage and transportation only left green chlorophyll, so that it appears green, and if excessive heating or storage time is too long, the chlorophyll is also decomposed, the laver will turn dark brown. We can roughly judge the freshness of the laver according to its color, but it is absurd to judge that it is a plastic bag.

In fact, it is easy to tell if the seaweed is made from a plastic bag. 'The plastic bags do not absorb water and there are water beads on the surface,' Mr. Ruan said. Laver absorbs water and has a smooth surface without water beads. Plastic bags are elastic and become thinner and longer when pulled; Nori has very little elasticity and is difficult to stretch.

For the video of "laver is made of plastic bags", some experts refuted the rumor on the cost and motive of the counterfeiting. "Laver itself is not expensive, there is no profit in counterfeiting with plastic bags, and the motivation for counterfeiting is insufficient." Zhu Yi, an associate professor at the College of Food Science and Nutrition Engineering at China Agricultural University, stressed in an interview with the media.

(Our reporter Chen Haibo)