Modulation of Structural and Physical-Chemical Properties of Fish Gelatin Hydrogel by Natural Polysaccharides

Gelatin, a water-soluble protein, shows unique gellification properties, which determine the active commercial availability of gelatin hydrogels in modern alimentary, cosmetic, and pharmaceutical applications. The traditional sources of gelatin for industrial technologies are pork and bovine skin and bones, which sometimes produce religious and some other restrictions. In recent years, there has been a significant increase in the production of gelatin from alternative sources, such as raw fish materials. Unfortunately, fish gelatin is characterized by weak gelling ability and a decrease in gelation and melting temperature, which are a consequence of the amino acid composition and structural features of fish gelatin. One of the ways to strengthen the natural gelling properties of fish gelatin is the structural modification of gelatin hydrogels by the introduction of polysaccharides of various natural origins. We have studied the association of our laboratory-made fish gelatin with three polysaccharides, namely, κ-carrageenan, alginate, and chitosan, which have distinct chemical structures and gelling capabilities. Structural features of the studied systems were analyzed by small-angle X-ray scattering (SAXS), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). We applied computer modeling of molecular interactions between fish gelatin and polysaccharides by means of molecular docking and molecular dynamics approaches. The existence of a correlation between the structure of gelatin-polysaccharide systems and their physicochemical properties was demonstrated by wetting angles (flow angles) and dynamic light scattering (DLS) studies of hydrodynamic sizes and surface ζ-potential.