Effect of skin concentration on properties and film-forming ability of gelatin from tilapia skin by hot-water extraction

The effect of skin concentration on properties and film-forming ability of gelatin from tilapia skin by hot-water extraction was investigated. As a result, both the viscosity and gel strength of gelatin were increased with increasing the skin concentration in the hot water from 7.5% to 10.0%, while decreased when the skin concentration was further increased. Similar trend was also observed in the mechanical properties of films prepared from gelatin. When skin concentration in the hot-water was 10.0%, the gel strength of extracted gelatin was 281 g and tensile strength of prepared films was 60 MPa. However, no significant differences in the amino acid composition and protein fractions were found irrespective of skin concentration in the extraction water. Based on the results of differential scanning calorimeter and circular dichroism, it was concluded that when gelatin was extracted from tilapia skin with hot-water at skin concentration of 10.0%, the degree of random coil in the gelatin was relatively low, while the thermal stability of gelatin films was the highest.