Preparation and characterization of edible gelatin films from tilapia (Tilapia zillii) scales

Edible films based on the gelatin from tilapia scales were prepared. The effects of temperature and time of gelatin extraction, along with glycerol concentration on the film properties such as tensile strength (TS) and elongation at break (EAB) were also investigated. The extraction yield of scale gelatin was increased with increasing extraction temperature and time. TS of films prepared from the scale gelatin which was hardly degraded when extracting at 80℃ for 0. 5h or 1h, could reach a higher value at around 44MPa. When glycerol concentration in gelatin films was increased from 20% to 50%, TS of films was decreased from 44. 09MPa to 16. 45MPa, while EAB, water vapor permeability and transparency value was increased. However, the color of gelatin films was not markedly influenced by glycerol. SDS-PAGE patterns of gelatin films containing glycerol of different concentration showed no differences in the protein bands. Based on the DSC analysis, the glass transition temperature (Tg) of scale gelatin films with glycerol concentration of 20% could reach to 113. 97℃, but decreased significantly with the glycerol concentration increasing.