Donkey-hide gelatin

Donkey-hide gelatin or ass-hide glue () is gelatin obtained from the skin of the donkey ("Equus asinus") by soaking and stewing. It is used as an ingredient in the traditional medicine of China, where it is called ejiao ().
The gelatin is produced in several coastal provinces of China: Jiangsu, Zhejiang, Shandong. Shandong's Dong'e County was where "ejiao" got its name.
According to a ca. 1723 account by the French Jesuit Dominique Parrenin, there was a well in Dong'e which was normally kept closed and sealed, and which was only opened when water was taken to be used in preparation of "ejiao" for the emperor's court.
Manufacture.
According to Parennin, the product was traditionally prepared during the late fall and winter (from after the harvest and until the beginning of March). It was supposed to be made from the skin of a recently killed well-nourished black donkey. Since the supply of this material was rather limited, it was said that a large amount of "fake" ejiao was also manufactured, using skins from mules, horses, camels, pigs, and sometimes, it was said, even from old shoes; a bit of "real stuff" was added to it, to deceive consumers.
Ejiao is either prepared as dry gelatin or mixed with powdered oyster shell or pollen to form glue balls. It tastes sweet.
Jesuits noted that while the "real" "ejiao" has no disagreeable taste or smell, the fake product could be distinguished by its unpleasant smell and taste, even when it was made from pig skins (which, supposedly, provided the best approximation of the real thing).
In the 21st century, ejiao manufacturers experience problems with the supply of genuine donkey hides, as fewer people raise these animals these days. The decreasing supply combined with strong demand for ejiao has led to greatly increased prices for donkey hides in China. This trend is also supported by restrictions on importing animal hides from outside the country. Qin Yufeng, the chairman of a major ejiao manufacturer and a member of Shandong's provincial legislature, has advocated for government support for donkey husbandry.
Donkey thefts and population declines.
In the mid-2010s, donkey prices in many places around the world began to rise sharply with demand for Chinese traditional medicine. Uganda, Tanzania, Botswana, Niger, Burkina Faso, Mali, and Senegal have banned donkey exports to China. In November 2017, eyewitness footage showing baby donkeys being bludgeoned to death with sledgehammers or killed by having their throats cut was released by PETA Asia. In November 2019, The Donkey Sanctuary reported that 4.8 million donkey hides were required to satisfy the global demand for ejiao, resulting in steep declines of donkey populations around the world. Donkey populations are declining in the NorthEast of Brazil, due to Chinese demand.
Applications.
In China "ejiao" is a traditional medicine used for different types of illnesses. An amount of 5 to 10 grams may be dissolved in hot water or wine and mixed with other ingredients in the traditional Chinese "materia medica" or taken alone. It is believed that donkey-hide gelatin treats a variety of conditions such as bleeding, dizziness, insomnia and a dry cough.
Quite a few manufacturers produce an "ejiao" bar called "gu yuan gao" (固元膏) in Shandong province. Gu yuan gao is made up of "ejiao", nuts, sesame, Chinese dates and cooking wine. It can also be used as an edible coating for dates, producing another type of snack.
"Ejiao" is also used for applying "di mo", a special paper-like musical reed membrane, to the "dizi", a transverse Chinese flute; it dries quickly, holds quite firmly, and is water-soluble, allowing later replacement of "di mo".
The molecular basis for its usage in treating anemia has been shown at least in part from the peptidic components combining multiple approaches. The hematopoietic effect of "colla corii asini" ("ejiao") may benefit cancer patients suffering from myelosuppression due to radiotherapy or chemotherapy.