Physicochemical properties of gelatins extracted from skins of different freshwater fish species

The aims of this study were to determine the physicochemical properties of extracted gelatins from four freshwater fish skins: snakehead (Channa striatus), catfish (Clarias batrachus), pangasius catfish (Pangasius sutchi) and red tilapia (Oreochromis niloticus) and compare with those of commercial gelatins from cold water fish skin and bovine skin. The extraction yields for four types of extracted gelatins were high, ranging from 10.78% (w/w) (pangasius catfish gelatin) to 27.79% (w/w) (catfish gelatin). Four extracted gelatins showed lower protein content and higher lipid, moisture and ash content compared to both commercial gelatins. Red tilapia gelatin presented the highest gel strength (487.61 g). At 60°C, the shear viscosity of catfish gelatin (5.24mPa.s) was the highest. Four extracted gelatins had higher pH, isoionic point and turbidity compared to the commercial gelatins. These extracted gelatins were white in appearance and had higher L* value and lower a* value than both commercial gelatins.