Extraction and characterizations of halal gelatin biopolymer from black tilapia bones and scales

Gelatin is a natural polymer with extensive range of applications in food and non­food industries derived from mammalian animals. In recent times, the growing Halal issues related to porcine gelatins have led to the increase in emphasising research on marine-life based gelatins. However, fish gelatins possess high ash content which deteriorates its quality. Besides, the inferior properties of fish gelatins such as low gel strength, viscosity and melting temperature, make them less competitive compared to mammalian gelatins. Hence, this study is aimed to extract gelatin from Black Tilapia (Oreochromis niloticus) bones and scales with more emphasis on the extraction methods to produce a high quality gelatin. Gelatins were extracted via hydrochloric (HCI) acid pre-treatment and thermal hydrolysis method by manipulating acid concentrations (0.2 to 1.4 M), pre-treatment time (4 to 32 h), extraction temperature ( 45 to 85 °C), and extraction time ( 4 to 12 h). The yield, colour and turbidity, gel strength, viscosity, melting temperature,. amino acid and proximate compositions of the gelatins had been determined. Results obtained indicate, treatment with 1.0 M HCl for 24 h and 0.6 M HCl for 8 h as the most suitable pre-treatment conditions for bones and scales, respectively. The yield, gel strength, viscosity and melting temperature for gelatins extracted at 65 °C for 4 h were found to be 7.29 ± 0.16 %, 1.28 ± 0.03 N, 6.99 ± 0.17 cP, 20.9 ± 0.7 °C for bone gelatin and 12.04 ± 0.52 %, 3.13 ± 0.05 N, I 0.80 ± 0.42 cP, 26.0 ± 0.5 °C for scale gelatin, respectively. Subsequently, the effects of ultraviolet (UV) light on properties of bone and scale gelatins had been investigated. Gelatins were exposed to UVA and UVC irradiation for 0.5 to 2.5 h. Treatment with UVA and UYC improved the gel strength and viscosity of scale gelatins, but contrarily decreases the properties of bone gelatins. In general, scale gelatin showed excellent properties compared to the bone and commercial b