Rheological properties of gelatin prepared from the swim bladders of freshwater fish Catla catla

The swim bladders of fresh water carps are small in size and normally discarded. The utilization of swim bladders for the preparation of gelatin will open up a new avenue for a better disposal of carps processing waste and good returns for aquaculturist. In the present study, gelatin was prepared from the swim bladders of Catla catla (Catla) and its physicochemical and rheological properties have been assessed. The yield of gelatin from the swim bladders was 13.5% (w/w). The amino acid profile of the gelatin revealed a high proportion of glycine and imino acid residues. SDS-PAGE pattern of the gelatin revealed two major bands corresponding to a α-chain and cross-linked component (β-chain). The Bloom strength of solidified gelatin was 264.6 g. The gelling and the melting temperature of gelatin were 13.7 °C and 23.3 °C respectively as determined by Controlled Stress Rheometer. The flow properties of gelatin solution revealed non-Newtonian behaviour with shear thinning phenomenon. The thixotropic area of flow curves increased with the temperature at any given concentration studied. The Casson and Herschel-Bulkley models were suitable to study the flow behaviour of gelatin solutions. The Arrhenius model was used to describe the temperature dependency of viscosity. The activation energy (Ea) of the gelatin was proportional to the concentration.