Otherwise known as "donkey-hide gelatin", E-gelatin is extracted from high-quality donkey hide by boiling. With a long history of more than 2,000 years, E-gelatin is honored as one of the "three treasures of Chinese medicine", the other two being ginseng and pilose antler.

E-gelatin was called "a sacred medicine" by Li Shizhen in his Compendium of Materia Medica. The earliest record of E-gelatin was in Emperor Shennong's Classic of Materia Medica some 2,000 years ago. E-gelatin was initially extracted by boiling cowhide before the E-gelatin extracted from donkey hide was proved to be a more effective medicine in the Tang Dynasty. From then on, cowhide was replaced by donkey hide, and it is still the case today.

The main material for E-gelatin production is donkey hide, and there are a dozen or so auxiliary materials which include crystal sugar, rice wine and soybean oil etc. E-gelatin is boiled through traditional processes using the well water of Dong'e containing multiple mineral substances. It takes a long time to produce E-gelatin, and there are stringent rules on the processing procedures which include more than ten steps, such as material selecting, washing, hide melting, extracting, cutting, and cool drying etc.

E-gelatin comes in regular rectangular blocks that are usually about 8.5cm in length, 3.7cm in width and 0.7—1.5cm in thickness. The blocks are brownish black or jet black with the smooth and shiny surface, and they are slightly transparent when viewed toward the light. E-gelatin is a hard, crisp and fragile substance and the section is brownish black or jet black, with no stench. If the E-gelatin stays equally hard before and after summer, it is of good quality.