Comparison of Skin Gelatins from Fishes Cultured at Different Aquaculture Water Temperatures

The preparation and characterization of fish gelatins are important for the high-value-added utilization of fish skins in the field of food industry. The purpose of this work was to study the effects of fish culture temperatures on the preparation and properties of fish gelatins. Three types of skin gelatins (TSkG: tropical tilapia skin gelatin; GSkG: warm-water grass carp skin gelatin; RSkG: cold-water rainbow trout skin gelatin) were extracted and studied. The fat-binding ability slightly decreased with decreasing water temperature: TSkG (16.8 g/g) > GSkG (16.4 g/g) > RSkG (16.2 g/g). For the fish oil-loaded emulsion at 10 g/L gelatin concentrations after 28 days of storage at room temperatures, the creaming indexes were 17.5% (GSkG) < 31.7% (TSkG) < 44.7% (RSkG). The emulsion stability order (GSkG > TSkG > RSkG) was consistent with the orders of the turbidity of the gelatin solution and the emulsifying activity index and reversely consistent with the orders of the relative amounts of 120–300 kDa bands (mainly β, α1, and α2 chains) of all the bands and relative amounts of α1 chains to the three chains. This work provides useful knowledge to understand the effects of fish culture water temperature on the molecular composition of collagens in fish skins and the properties of the obtained fish skin gelatins.