Gelatin does not exist naturally in nature. It is a heterogeneous polypeptide mixture formed by partial hydrolysis and degradation of collagen-containing tissues such as skins, bones, tendons and scales of animals (cattle, horses, pigs, fish and donkeys) after a series of chemical treatments, and consists of more than 20 amino acids. Glycine accounts for 1/3, and the sum of proline and hydroxyproline accounts for 1/3. (Note: Collagen is the main component of animal skin, bones, tendons and other connective tissues, so it mostly exists in animal skin, bones, cartilage, ligaments, muscle membranes and fish phosphorus; Polypeptide is the constituent unit of protein, and protein is composed of one or more polypeptides. )

Physical and chemical properties of gelatin

1) freezing force (also called gel strength and Blum freezing force)

Under strict conditions, when a cylinder with a diameter of 12.7mm is pressed 4mm below the surface of jelly containing 6.67% gelatin, the applied force represents the freezing force.

The freezing force index indicates the hardness of the glue after cooling and solidification, and indirectly indicates the firmness or tension of the glue. Freezing power is an important index to reflect the internal quality of gelatin, and the unit is Blumk.

2) Brinell viscosity

The viscosity of gelatin solution determines the film-forming characteristics of gelatin (one of the keys of capsules), and viscosity indicates the length and molecular weight of polypeptide chain in gelatin. The longer the polypeptide chain is, the more unfavorable it is to form a network structure, and the greater the viscosity is. Generally speaking, the viscosity of gelatin is high, which means that it has high water absorption and large molecular weight, and it is less damaged during the preparation of gelatin.

The viscosity of gelatin solution can be used to distinguish or detect and control the purity of gelatin, which plays an important role in improving the quality of gelatin and capsules. The greater the freezing force of gelatin, the stronger the tensile force and elasticity of the capsule, the uniform thickness and the difficulty of deformation.

The dissolution rate and solidification rate of high viscosity gelatin are faster than those of low viscosity gelatin.