Leather Experts Explain Leather Waste And "Poison Capsule".

In April and May this year, the incident of processing old yogurt and medicinal capsules on leather leftovers after the media exposure, the whole country was bubbling with excitement.

For this reason, we interviewed the famous leather and protein experts in China, the director of national leather technology research and Extension Center, and the director and doctoral tutor of the leather and protein research center of Yantai University.

Professor, he has talked about some different views from media reports, which is publicly published and puzzled by the interpreter.

1. now about old leather shoes, "old yogurt" and "medicinal capsule" is a hot topic discussed by people. The major media are competing to report. What do you think of this?

Since the so-called old

After the exposure of the "old yogurt" and the industrial gelatin capsule, I paid close attention to media coverage and public opinion as an insider, and found that many news lacks professionalism to attract attention, cater for public opinion, violate science and violate facts.

More than a dozen domestic and foreign media interviewed me, but they were incomplete.

Now that the storm is over, we can reflect and review the real situation of the storm with a calm and systematic reflection.

2. what is gelatin? What are the main raw materials for gelatin preparation?

Gelatin is a colloidal product formed after hydrolysis of collagen.

Collagen is found in the cortex, bones and tendons of animals.

Gelatin production at home and abroad is made up of waste materials from tanneries, fur factories and slaughterhouses.

Tannery leftovers include tanned leftovers and tanned leftovers.

The former is treated with detergent, strong alkali, strong acid and so on, showing white, also known as white leather leftovers; the latter is usually blue, also known as blue leather leftovers, such as sheet leather, trimming of the remaining material, shavings and leather grind.

Blue leather leftovers are made of chrome salt. They all contain chromium, mainly trivalent chromium, some contain six of the price, and six valence chromium is harmful to human body. Therefore, blue waste can not be used to produce edible gelatin, and it can only produce industrial gelatin.

White leather leftovers are not tanned, chrome free, industrial gelatin and edible gelatin can be produced.

Of course, the blue leftovers can also produce gelatin through strict dechromic treatment. Even if gelatin produced without dechromic treatment is reasonable, it can be eaten theoretically, but in order to avoid suspicion and prevent unscrupulous enterprises from acquiring loopholes, our country stipulates that blue waste can not be used as edible gelatin.

3. what is the difference between industrial gelatin and edible gelatin?

　　工業明膠無論白皮或藍皮下腳料均可制得，而食用明膠只能由生皮下腳料制造;對于食用明膠有一個檢查標準，二氧化硫含量不得高于0.015%，砷含量不得高于0.0002%，重金屬(鉛、鉻等)含量不得高于 0.005%，而工業明膠則沒有這方面的規定;工業明膠用途非常廣泛，主要用來做膠黏劑(例如紙箱、三合板和木工粘合劑)、紙張施膠劑(主要用來增加紙張硬度、光亮度，改善紙張外觀)、絮凝劑(應用在采礦、選礦和廢水處理中)，另外紗布、砂紙、火柴都必須用工業明膠，就連我們天天使用的鈔票，從造紙到油墨印刷都離不開工業明膠;而食用明膠主要用來增加食品粘度、稠度、光亮度和彈性，提高乳狀食品的穩定性，改善食品的口感等，冰淇淋、蛋糕、奶粉、香腸、果凍生產中經常用到。

It is worth pointing out that gelatin is a protein product, adding edible gelatin to food can improve its nutritional value.

Traditional Chinese medicine "donkey hide gelatin" is one kind of gelatin.

4. what are the uses of leather waste?

The leather with only 30~40% of total weight is made into leather, and the remaining 60~70% is dissolved in water and discharged. Most of it is solid waste, also known as leftover material.

In addition to fat and sarcolemma, the main chemical composition of leftovers is collagen.

Leather leftovers are commonly used to produce gelatin and regenerated leather.

Leather and leftovers are raw materials for gelatin production both at home and abroad. Some media claim that "illegal manufacturers make gelatin from leather leftovers", which is wrong.

In any country, gelatin is made from tannery and slaughterhouse leftovers.

In addition to gelatin production, white leftovers can be used directly as fodder, often used in raising mink or fox, or hydrolyzing leftovers into crude protein as additives for livestock and poultry feed, or refining additives for milk, milk powder, food and beverages to increase their nutrition. They can even be further refined into moisturizing cosmetics, such as facial milk, hair cream, hair spray, especially facial milk. Besides moisturizing, they also have good wrinkle resistance.

If the blue waste is removed completely, it can be used as a white leather leftover to make nutriment and cosmetics for human and animal consumption.

At present, in order to avoid suspicion, factories are usually made of recycled leather, fiber leather and non edible chemicals.

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Recently, my master and PhD students made leather degreasing agent from scrap leather, which was directly used in leather making or fur production, and opened up a new way for making full use of leftovers.

5. can old leather shoes be made of "old yogurt" and "medicinal capsule"?

Gelatin is hydrolyzed from collagen, while collagen content in raw skins accounts for about 97% of dry matter, so leather is the main raw material for gelatin.

In leather shoes, only the outer layer of the upper is made of leather, which accounts for about 30% of the total weight of leather shoes.

In addition, these leather products are processed by fatliquoring, dyeing and finishing processes. They contain chemical materials such as dyes, Oils and so on, and have a thick coating layer (also known as leather paint) on the surface. They are synthetic materials and can not be used to make gelatin.

To make gelatin from the outer layer of the upper, it is necessary to remove the paint, dyestuff and grease. The removal process is very complicated and the cost is high, and the quality of the gelatin produced is poor.

Therefore, theoretically speaking, the outer layer of old leather upper can produce gelatin, but it is not worthwhile from the economic efficiency and product quality, and its cost is much higher than that of ordinary edible gelatin.

Leather tannery waste material is very cheap, wet blue leather leftovers are only 100~300 yuan per ton, and can be directly processed without processing. Therefore, it is not cost-effective to make gelatin from leather shoes.

I have been engaged in leather and protein research for more than 30 years, and I have never seen any examples of gelatin production with leather shoes.

To give an exaggerated example, planting Chinese cabbage can use the general soil on the earth. There is no need to use Mars soil to pretend to be the earth's soil. The quality of Martian soil for planting Chinese cabbage is poor, and the two is the high cost.

Therefore, it reminds the friends of the news media to note that the production of old yogurt from old leather shoes is nothing but a case in the world.

If anyone finds out which companies use old leather shoes to produce gelatin for old yogurt and form a commercial scale, I would like to offer a reward of 100 thousand yuan.

Is 6. chromium this metal element harmful to human body?

Chromium, it sounds strange, in fact, our daily life can not do without chromium, such as cooking rice pot, spoon, key ring, buckle and so on.

All stainless steel and all electroplating layers are made of chromium (and a small amount of nickel), and no one reflects any harm.

In addition to the unstable two valence chromium, the common chromium is divided into three valence states. The first is zero valent chromium, which is the stainless steel and electroplating materials in our daily life.

The second one is six valent chromium, which is orange yellow in the valence state of chromium, commonly known as potassium sulfate. Six valent chromium is a highly toxic oxidizing agent. It is corrosive and is commonly used in the preparation of electroplating fluids and commonly used lotions in chemical industry.

The six valence chromium is mainly irritating to the respiratory tract and digestive tract of the human body, and adults will be killed if six valent chromium exceeds 1.5g.

The third kind is trivalent chromium, because its ionic water solution is blue, also known as blue vitriol, mainly used for leather making and pigment production.

Only trivalent chromium has tanning property. The six valence chromium has no tannage and has a destructive effect on leather. Therefore, tanning plants only use trivalent chromium instead of six valent chromium.

Because of its special physiological functions, trivalent chromium is also an indispensable trace element in the human body. The daily demand of the human body is about 0.06~0.36mg. The lack of trivalent chromium can lead to the occurrence of diabetes. Therefore, the production of the elderly vitamins in the United States, such as "good care" and "Shikang" in our market, all contain trivalent chromium.

China is a poor chromium country. Proper supplement of trivalent chromium is of great benefit to maintaining the balance of normal glucose tolerance factors and reducing the risk of diabetes.

In addition to the prevention and treatment of diabetes, trivalent chromium can reduce the attachment of cholesterol on the arterial wall and prevent cardiovascular diseases. Trivalent chromium can regulate many physiological metabolism of human body, and it is very effective in repairing the damaged tissue and preventing the spread of cancer cells. Besides, three valence chromium has good effects on inhibiting the deformation of the lens and reducing the incidence of myopia in children.

However, excessive intake of trivalent chromium may cause cumulative damage to human body, but there is no clinical case.