Physicochemical Properties Of Gelatin From Skins Of Silver Carp (Hypophthalmichthys Molitrix) And Its Modification

Gelatin is derived from the fibrous protein collagen, which is the principal constituent of animal skin, bone, and connective tissue. Gelatin is produced via the partial hydrolysis of native collagen. In this thesis, hydrochloric acid was used as pretreatment agent to extract gelatin from the skins of silver carp. The extraction conditions of gelatin from silver carp skin were optimized by response surface optimization method based on single factor experiments, and the gelatin recovery and gel strength were used as response value. The optimum extraction conditions of fish skin gelatin were under 0.2 mol/L HCl for 30 min, water washed to neutral, then extracted in 55 ℃ warm water for 2.5 h. Under the optimum extraction conditions, gelatin recovery got 88.05%±1.52% and gel strength got 699.2±15.8 g. More than 20 physicochemical properties （including gel strength, viscosity, amino acid composition, polyacrylamide gel electrophoresis, ultraviolet absorption spectroscopy, fourier transform infrared spectrum, thermal denaturation temperature, pH, isoelectric point, thermal denaturation temperature, rheological property, freezing point, melting point, freezing time, sensory evaluation of odor, color, transparency, water activity, gel texture, moisture absorption, moisture retention, foaming and emulsifying properties） of gelatin from silver carp skin were determinated and compared with the bovine skin gelatin. The results showed that the gelatin from silver carp skin had better gel strength, viscosity, foaming and emulsification but lower freezing and melting point and poorer thermal stability than gelatin from bovine skin. Then, KCl, CaCl₂, carrageenan, gellan gum, genipin and transglutaminase were respectively used to modify the properties of gelatin. The results showed that the freezing point, melting point and thermal stabilities of gelatins modified by all above methods were improved significantly.