Получение товаров из кожи животных для медицинского применения и определение химического состава getting goods from animal skin for medical use and determination of chemical composition ibrohimjon Rahmonovich Asqarov

Research results. In our study, studies were conducted on the choice of the second hydrolysis time of collagen extraction by the method of alkaline salt hydrolysis. Collagen was hydrolyzed at a temperature of 18-23⁰C for 60, 80, 90, 120 minutes in order to obtain a biopolymer film from the water mass with optimal physical and mechanical properties. The physicochemical parameters of the obtained water mass of neutral collagen were studied [13. P. 52; 14. P. 7]. The results of the study are presented in table 3.
The results in Table 3 show that the amount of collagen in the raw material decreased as the second hydrolysis time increased. In particular, at a hydrolysis time of 60 minutes, an aqueous mass was obtained containing 5.5-6.2% collagen. This collagen sample was technologically flexible and difficult to mold, which made it difficult to obtain a composition and a biomaterial based on it.
Table 3
Physico-chemical indicators of the water mass of collagen

№	Second hydrolysis time, min	The amount of collagen in the water mass (g,)	Relative density (g/sm^3)	Solubility in 6% acetic acid
1	60	5.5-6.2	0.295-0.310	dissolves
2	80	4.8-5.5	0.280-0.293	dissolves
3	90	4.2-4.6	0.262-0.278	dissolves
4	120	3.8-4.1	0.246-0.257	dissolves

During the second hydrolysis for 80 minutes, a water mass was obtained containing 4.8-5.5% collagen. In view of the readability of this mass and the ease of its molding, this hydrolysis time was chosen when obtaining the composition and biomaterials.

When conducting the second hydrolysis time for 90 minutes, an aqueous mass was obtained containing 4.2-4.6% collagen. Although the obtained collagen is well read and easily molded in terms of physical and mechanical properties, it was found that the strength of biomaterials based on them is very low (2.7 MPa).
During the second hydrolysis for 120 minutes, a water mass was obtained containing 3.8-4.1% collagen. Due to the relatively low permeability of the obtained collagen and the complexity of molding, it was not possible to obtain a composition.
The specific densities of the hydrolyzed collagen samples were determined a second time. In particular, the specific gravity of the hydrolyzed collagen sample in 60 minutes was 0.295-0.319 g/cm³, in 80 minutes - 0.280-0.293 g/cm³, in 90 minutes - 0.262-0.278 g/cm³, in 120 minutes it was 0.246.-0.257 g/cm³. As a result of the research, it was found that the amount of collagen in the raw material decreased with an increase in the second hydrolysis time. This is due to the fact that under the action of an alkaline environment, a certain part of the collagen in the raw material undergoes complete hydrolysis, which is explained by a decrease in its yield.
After the second hydrolysis, i.e. all collagen samples hydrolyzed by the alkaline-salt method for different periods of time are dissolved in 6% acetic acid to form a transparent gel [15. P. 111].
In the course of the study, the viscosity of solutions obtained on the basis of water masses of collagen with different hydrolysis times was determined viscometrically.
To determine the viscosity - 0.01 in 6% acetic acid of the aqueous mass of collagen isolated by secondary hydrolysis for 60, 80, 90 and 120 minutes; 0.02; 0.025; 0.03; 0.0375; prepared 0.05% solutions. The viscosity of the solution was determined using a capillary viscometer at a temperature of +20±1°C. To calculate the relative viscosity, the viscosity of the solutions was determined at various concentrations, and the results obtained were graphically extrapolated to zero concentration. As a result, it was found that the viscosity of collagen solutions depends on the concentration of the solution (Fig. 2).
The minimum value of [η], which describes the three-helix monodisperse conformation of the collagen molecule, is 10–11 [16. S. 108], the viscosity decreases with increasing hydrolysis time. In particular, for denatured collagen, i.e. gelatin, the value of [η] is 0.1 [15. P. 67].