Water resistance and mechanical property improvement of tilapia (Tilapia zillii) scale gelatin films by dehydrated thermal treatment.

The effect of dehydrated thermal treatment on the tilapia scale gelatin films was investigated to improve their water resistance and mechanical properties. The gelatin extracted from tilapia scales was mainly composed of β-chain, α-chain and their degraded products with imino acid content of 21.2 %. When the films prepared from tilapia scale gelatin were heated at 80 °C, no significant changes in the properties of films were observed. As heating temperature was increased to 100 or 120 °C, the tensile strength of films was increased gradually with increasing thermal treatment time, while film solubility and protein solubility were decreased. Based on the SDS-PAGE analysis and the protein solubility of the gelatin films in various protein denaturant solutions, it was found that the cross-linking in the gelatin film network between β-chain and α-chain could be induced by heating at 120 °C. It was revealed that the main interactions involved in the gelatin film formation were changed from ionic bonds and hydrogen bonds to hydrophobic interactions and covalent bonds, leading to improve water resistance properties of films.