Effect of extraction variables on the physical and functional properties of tilapia gelatin

In this study, the effects of different extraction temperatures (45, 60 and 75 °C) and pH (3 and 5) on the physical and functional properties of tilapia skin gelatin (TSG) were investigated. The extraction yield of TSG is from 11.67 to 41.91% (based on dry weight), and the highest was obtained at 75 °C/pH 3. The TSG extracted at 45 °C showed strong band intensity of α-chains and cross-linked components with higher molecular weight (MW) > 120 kDa, while other TSG samples resulted in faded bands with the presence of fragments (<85 kDa). Higher contents of imino were detected in TSG with higher MW. Gel strength, apparent viscosity, and gelling temperature varied with different extraction temperatures and pHs, where higher values were observed in TSG with higher MW. These results are supported by circular dichroism analysis, in which more triple helix structures were found in TSG with higher MW. All TSG solutions can form gels at 4 °C, while at room temperature, only TSG obtained at 45 °C can set. These results highlight the significance of extraction conditions which may be used to tailor the physical and functional properties of TSG.