НАУЧНОЕ ОБОСНОВАНИЕ ФИЗИЧЕСКИХ СВОЙСТВ РЫБНОГО ЖЕЛАТИНА

Abstract

The article presents the advantages of fish gelatin available for nutritional purposes in comparison with gelatin of mammals. Factors forming the basic physical properties of gelatin as a structure-forming agent have been identified. The analysis of melting temperature of jelly and the dynamic viscosity of fish gelatin solutions has been carried out. The melting temperature of jelly prepared from fish gelatin is 4°C lower than the minimum normalized value for mammalian gelatin, which is stipulated by the specific features of their amino acid composition. There has been found an increased value of the parameter “dynamic viscosity” (on average 30 mPa·s) in comparison with the standard value of gelatin of animal origin (on average 23 mPa·s). The molecular weight composition of fish gelatin has been determined. Gelatin has been stated not an individual substance, but a multiphase system consisting of a mixture of linear polypeptides and their aggregates. In the molecular weight distribution of fish gelatin 81.7% falls to a high molecular weight fraction with a mass higher than 100 kDa. Compared with gelatin obtained from the skins of cattle fish gelatin has higher content (by 34.7%) of molecular weight fractions (β- and γ-chains) and lower content (by 36.2%) of α-chains. The predominance of high molecular weight fractions in the composition of fish gelatin causes high rates of dynamic viscosity of its solutions. It was established that the interval of temperature transition ‘fibril-globule’ in fish gelatin is 20-25°C, and in animal gelatin - 28-30°C. It has been inferred that the thermal dependences of the rheological properties of fish and animal gelatin are different. It has been substantiated that collagens of different origin give gelatin with different properties. Physical properties of fish gelatin depend on the amino acid composition of a gelatin molecule, which is determined by the nature of collagen, and on the molecular weight distribution of α-, β-, γ-fractions of gelatin, which is determined by technological factors of gelatin production.