Effect of Heating Method and Heating Time on Physicochemical Properties of Fish Gelatin

In order to explore the effect of heating method and heating time on physicochemical properties of fish gelatin, the protein composition, viscosity, rheological properties and thermal stability of heated gelatin solutions, and the gel strength, texture profile analysis (TPA) parameters and microstructure of gelatin gels were analyzed and compared. The results showed that the viscosity, rheological properties and thermal stability of fish gelatin solutions decreased significantly with the increase of heating time, while the change extents of these properties in the intermittent heated gelatin were less than those in the continuous heated gelatin. When gelatin was heated for 48 h continuously, the β band disappeared in the electrophoresis pattern, and the α₁ and α₂ subunits degraded obviously after being heated for 96 h. When gelatin was heated for 96 h intermittently, the β band disappeared. The gel strength and TPA parameters of the gel prepared by fish gelatin gradually decreased with the increase of heating time, whereas the gel properties of the intermittent heated gelatin were superior to those of the continuous heated gelatin. Scanning electron microscope results showed that the surfaces of continuous heated gels were smooth and flat, while the structure of gel prepared by intermittent heated gelatin was rougher and more porous. The results suggested that intermittent heating and the heating less than 12 h could reduce the heat degradation of gelatin.