Ejiao, also known as can-covering glue and donkey skin glue, is a rubber block made of donkey skin. The preparation method is as follows: firstly, scrape the donkey skin, cut it into small pieces, and boil it in water for 3 days and nights. When the juice is sticky, take out the donkey skin pieces and then boil them in water. After this is repeated for 5-6 times, the boiled donkey-hide gelatin juice is filtered to remove impurities, concentrated into thick paste by fire, concentrated, dried in the shade, and caked to obtain the medicinal donkey-hide gelatin. The first-grade Ejiao is black in color, transparent and bright, and has no fishy smell. It is better that Xia Hou is neither wet nor soft. Ejiao is mainly produced in Shandong, Zhejiang, Beijing, Shanghai and other places. The most famous producing area is Dong 'e Town, Pingyin County, Shandong Province.
Chinese medicine believes that Ejiao is sweet and flat, and has the effects of nourishing yin, enriching blood and preventing miscarriage. According to research, Ejiao contains a variety of protein, amino acids, calcium, etc., which can improve the blood calcium balance and promote erythropoiesis. In addition, Ejiao can raise blood pressure and prevent hemorrhagic shock, and it also has a good preventive effect on progressive muscular dystrophy in animal experiments.
In traditional Chinese medicine, Ejiao is the best medicine in gynecology. Clinically, it is mostly used to treat women's fetal, menstrual and obstetric diseases and some internal medical diseases. Colla Corii Asini, Ligusticum Chuanxiong, Glycyrrhiza uralensis, Radix Angelicae Sinensis, Radix Rehmanniae Preparata, Folium Artemisiae Argyi and Radix Paeoniae Alba are used together as "Jiao Tang Ai" in Synopsis of the Golden Chamber, which is mainly used to treat abdominal cold pain during pregnancy or postpartum hemorrhage. Colla Corii Asini combined with Folium Artemisiae Argyi can prevent and treat abortion, abdominal pain and bleeding. Colla Corii Asini plus Radix Astragali and Fructus Jujubae can treat shortness of breath, fatigue, dizziness and palpitation caused by excessive bleeding or menstrual flow during delivery. Colla Corii Asini combined with Cortex Mori, Gypsum Fibrosum, Almond, Glycyrrhrizae Radix, Radix Rehmanniae, Radix Ophiopogonis, Fructus Cannabis and Folium Eriobotryae as "Qingzao Jiufei Decoction" can treat dry mouth, dry nose, dry cough and scanty phlegm. Colla Corii Asini combined with Pollen Typhae can treat hemoptysis and nosebleeds. Colla Corii Asini combined with Chinese ink can treat hematuria and hematochezia. Colla Corii Asini mixed with Poria, Polyporus, Alisma orientalis and Talcum can treat urinary tract infection. Take donkey-hide gelatin, add onion honey and decoct it, which can treat the elderly or the weak. Colla Corii Asini is mixed with Rhizoma Coptidis, Scutellariae Radix, Radix Paeoniae Alba and black-bone chicken, namely "Huanglian Ejiao Decoction" in Treatise on Febrile Diseases. Can be used for treating dysphoria and insomnia.
It is worth noting that because Ejiao is greasy, it hinders the digestive function of the spleen and stomach, so there are fullness, indigestion and poor diet in the stomach. Traditional Chinese medicine belongs to the weak spleen and stomach, so use Ejiao with caution. In addition, Niu Pijiao and miscellaneous leather gum are often used as donkey-hide gelatin in the market, but they are hard and brittle, and smell of sesame oil after heating. These fake and shoddy products are sticky and not easy to break, and they give off a strong fishy smell or peculiar smell when heated. Buyers can be identified by this.