Modeling the impact of extraction conditions on functional properties of gelatin from scale of Blackspotted croacker (Protonibea diacanthus)

Abstract

Utilization of waste from fish processing industry for value added products is gaining considerable attention as it addresses environmental pollution issues and adds economic returns to the industry. Scales of Blackspotted croaker were utilized for the extraction of gelatin and response surface methodology (RSM) with central composite design was employed to determine the optimal conditions of three independent variables namely concentration of sodium hydroxide (X1), extraction temperature (X2) and extraction time (X3) on yield (%), gel strength (g), viscosity (cP) and melting point ( C). The models obtained by RSM produced a satisfactory fit to the data with respect to gelatin yield (R2 = 0.931, p \ 0.01), gel strength (R2 = 0.957, p \ 0.001), viscosity (R2 = 0.847, p \ 0.05) and melting point (R2 = 0.876, p \ 0.05). The maximum values of the responses were obtained at a combined condition of sodium hydroxide concentration, extraction temperature and extraction time of 0.4 %, 80 C and 3 h respectively. The predicted maximum response values obtained from the models (7.82 % yield, 248.4 g gel strength, 10.11cP viscosity and 21.4 C melting point) were experimentally verified. Results from the present study clearly revealed that the mathematical models derived from RSM help in extracting gelatin from fish scales with the desirable functional properties.