Xu Yi smiled but didn't answer, and asked Liu Liping: "Before I said this, I asked you one thing, what should you do if the salted meat in your house is too salty?"

Liu Liping said without hesitation: "Take the water directly and soak it, and then change the water." ”

Xu Yi nodded: "The salted meat composed of such thick cells is blistered and light, not to mention such a thin stratum corneum." The pores in the membrane of the dead cells can not only allow water molecules to pass through guò, but also ions to pass guò. While the stratum corneum cells absorb water, it is inevitable that the ions inside the cells will be lost. Repeated immersion will inevitably result in fewer and fewer ions in the cell, and the denaturation of the colloid-forming proteins will result in only one result, and the dead cells will eventually absorb water more and more slowly. ”

Just like if you have changed the water a few times, on the one hand, you can accept the saltiness of the salted meat, on the other hand, because you can't absorb the water, and the salt soaked out of the outer layer and the inside is getting less and less, and there is a lack of enough ion gradient difference, if you want to go faster, you have to cut the salted meat into thin slices and soak it in the water, on the one hand, it increases the contact area, and on the other hand, it also makes the thickness of the water need to penetrate smaller, can you understand this?"

"Similar to this process of water entering the cell, normal cells will also lose ions, but the living can be transported back into the cell through some protein channels, but the dead cells can no longer be replenished by guò this pathway, and can only passively obtain ions through guò intercellular fluid and neighboring cells. Therefore, from the moment of death, the epidermal cells become farther and farther away from the basal layer, and their ability to obtain ions becomes worse and worse, and this ability to absorb water naturally becomes worse and worse. And that's not all. Although the cells of the stratum corneum are not as tightly bound as the basal layer, they are also filled with a large number of small particles formed by keratin encapsulating fat. This makes it more difficult for moisture or other substances to penetrate through. ”

Liu Liping nodded in understanding.

Xu Yi asked her again: "Let's take bacon as an example." What do you think is harder on top of a piece of salted meat or a piece of frozen meat after the dish is fried?"

"It must be the skin of the flesh, and if it takes a long time, you won't even be able to bite it. Liu Liping thought for a while and replied.

Xu Yi asked again: "Do you know why this is, even if you soak it in water for a longer time, it can't return to its original state?"

Liu Liping shook her head and said she didn't know.

Xu Yi explained the reason to her: "In fact, this is related to the particularity of the contents of skin cells, the skin is to protect the contents of the body, and this structure is naturally dense and strong, so under long-term evolution, the cells are filled with a large number of keratin filaments." The more mature the epidermal cells, the higher the amount of keratin in them. The more keratin, the denser the inside of the cell will be, which can make the stratum corneum well resist external invasions and protect the internal tissues, but this will inevitably increase the difficulty of water absorption of stratum corneum cells. ”

Liu Liping asked: "Keratin, it sounds very familiar, hair seems to be made of keratin, right?"

The fat man accosted beside him: "Almost, I remember that the keratin content of hair seems to be more than 90 percent, isn't that the case for the third child?"

"Yo. Yes, yes. Xu Yi smiled and gave the fat man a thumbs up.

The fat man smiled proudly and continued, "I also know that hair can also be acidified into amino acids. It is made into hydrolyzed protein powder and even used to make soy sauce. ”

Liu Liping made a retching motion, pointed at the astronaut and said, "Dead fat." The soy sauce you eat is made of your hair!"

The fat man is not annoyed, he can even say that the toad is dipped in pus at the dinner table. Nodding his head, he said, "Yes, the soy sauce made from the hair is very fresh." The braised pork just now was delicious, but I didn't miss it. ”

"It's not true, right?" As he spoke, Yan Peimin got up and ran to the kitchen, making a few people stunned, didn't this person run there and vomit again?

As a result, within two minutes, Yan Peimin ran back with a smile and said to Liu Liping: "Don't listen to the fat man's nonsense there, the bottle is printed on it, saying that the raw material is non-GMO soybeans!"

Yu Hangsheng sneered and shook his head: "Speaking of which, no one can guarantee that they must not have eaten this thing." To put it bluntly, I can't guarantee that I haven't eaten this soy sauce, or even that I haven't used it in my store. ”

Hu Yifei broke out in a cold sweat, stabbed the fat man, and asked him: "This is not true, right, you still have this thing in your house?"

The fat man shrugged his shoulders and said, "How is it possible, if you really enter this kind of thing, this store will be closed sooner, and my family is all soy sauce produced by regular manufacturers?"

"Then you still say that you don't guarantee that you haven't used it. ”

"This year, there is no food safety problem in the factory, it does not necessarily mean that the production is regular, before Sanlu has no accident, it is still a national famous brand quality exemption. Maybe these factories are more cheating and cheating, but the secrecy of this fraud is done well, or it is maintained by public relations with our national characteristics, and even central enterprises have a sky-high entertainment fee, can you say that there must be no greasy in this thing?"

The fat man sighed, and then said: "The umami of soy sauce is produced by the amino acids in it, look for it all over the supermarket, can you find a bottle that says soy sauce is prepared, and all of them say brewed soy sauce." To put it bluntly, the new national standard for soy sauce requires that the proportion of brewed soy sauce be indicated on the product label, but even if it says that 100% soy sauce is brewed, I dare not guarantee that this thing is really brewed, whether it is prepared or brewed is not something that can be detected by quality supervision, who dares to guarantee where the amino acid powder blended by those big factories is bought, and even I dare not guarantee that the amino acid powder they blend is food grade?"

"Really?"

The fat man nodded: "Blending this thing, you think it's really a three-no product to do the work, if you go to buy aged vinegar, I'm afraid that buying a hundred bottles may not be able to sell a bottle of really 100% brewed aged vinegar, which can ensure that the other party uses food-grade glacial acetic acid to burn high incense! Another example is our school canteen, saying that it is a bidding and procurement of raw materials, so that students can eat safe food, but you can really guarantee that those procurement personnel will not get some crooked things for their own selfish interests. Even the breakfast milk of primary school students is particularly spoiled and faked, this serves the people, do you think it is in vain?"

"These days, it's really hard to buy something that you can rest assured!" Hu Yifei sighed, but still reminded the fat man: "Let's just talk about some arguments in private, don't go out without a door, especially if you are still taking the civil service exam, beware of misfortune." ”

The fat man said with a hippie smile: "Hehe, don't worry, I'm not so unreliable, if we pass the exam, don't we also have to serve the people, can you really expect me to be a clean official who asks for his life for the people and reports his colleagues?"

"Well, forget about this topic, those things, let's talk about it after you pass the written test, not to mention that there is really any corruption, you better not tell us, beware that we accidentally get drunk and shake you out." Yan Peimin looked at the fat man, and then continued: "These processed things, ordinary people can't distinguish the real from the fake, just like the liquor in the distillery in my hometown was sold to the Biaowang distillery in Lu Province back then, and it became the liquor in Lu Province." ”

The fat man nodded: "Anyway, I don't have the ability to tell whether this soy sauce is brewed or not, maybe even the people from the Food Supervision Institute are drinking the hair soy sauce brewed by the 'pure soybeans' of which big factory!"

Liu Liping protested: "You're not done, this is too far off topic!" Then turned his head and asked Xu Yi: "Is keratin melanin?"

Xu Yi shook his head, "Keratin is a colorless and transparent protein, even the horn cells of hair are only in the outermost layer of hair, like a tile, layer upon layer to form a transparent film. The main component of keratin is melanin, which is the product of tyrosine catalyzed by melanocytes with tyrosinase, and has nothing to do with keratin. ”

Liu Liping nodded as if she didn't understand: "That's it, but don't people say that if you don't eat salt for a long time, you will grow white hair like a white-haired girl?"

Xu Yi's sweat is about to come down, let's not talk about the absorption of water from the skin, it's not the same as the hair, but he still explained to her: "If you don't eat salt for a long time, this person will have a water and electrolyte imbalance due to the lack of sodium ions and chloride ions, but he will not grow white hair because of this." ”

"Isn't that white-haired girl really a person?"

"It's true, but it's more likely that she's surviving in the wild, and she's not getting enough protein, resulting in severe malnutrition, but this is generally the result of her hair being scorched yellow and lacking pigment, so it won't make her hair turn gray because she doesn't have salt to eat, if the prototype of the story is really full of gray hair, the biggest possibility is that she has a hereditary, more powerful less white head. Xu Yi continued: "The story of the white-haired girl has been artistically processed, and many things are not credible. In a similar situation, there is also the story of Wu Zixu who crossed Shaoguan overnight and turned white, and there is also a text in which the story of King Li Chuang crossing the Yellow River with white hair and beard cannot be true. These can only be the result of literary processing, and it would be good to listen to it as a story, and the real situation is absolutely impossible. ”

"Why?"

Xu Yi said: "Hair, like the stratum corneum of the skin, is made up of dead cells. The current state of the human body may affect the hair roots that are growing, but it is absolutely impossible to change the state of the hair that has grown, so it is absolutely impossible for such a thing as a white head overnight! Nine times out of ten, Wu Zixu used no idea what method he used to dye or bleach his hair in order to avoid inspection. (To be continued......)