Properties of protein based film from gelatin of skin and bone of red tilapia (Oreochromis niloticus) as influenced by fish freshness

Abstract

The effect of storage time on the properties of gelatin film from skin and bone of red tilapia was investigated in this study. Fish were stored for 0, 7 and 14 days in iced storage. After storage, the skin and bone were obtained for extraction of gelatin. The gelatin yield of skin was increase as day storage increase (day O; 7.3%, day 7; 7.96% and day 14; 15.42%) while for gelatin yield of bone decreased as day storage increased (day O; 2.2%, day 7; 2.8%, day 14; 2.34%). Generally, films prepared from fish stored in ice for a longer time became less transparent, darker and more yellowish. Incorporating day storage decreased tensile strength (2.73 ± 1.34 MPa) and elongation at break percentage for skin gelatin film meanwhile tensile strength for bone gelatin film (5.41 ± 1.33 MPa) higher than skin gelatin film but inversely for elongation at break. Increasing day storage will increased UV and visible light barrier properties and film solubility but decreased water vapor permeability of the skin gelatin film. Compare to bone gelatin film, skin gelatin film have better physical attribute in term of tensile strength and water vapour permeability.