The effect of processing conditions on physico-chemical properties of whitecheek shark (Carcharhinus dussumieri) skin gelatin

The optimum conditions for gelatin extraction from whitecheek shark Carcharhinus dussumieri skin have been determined by response surface methodology (RSM). The experiment optimization has been conducted by central composite design (CCD), using NaOH concentration (0.01-1 N), HCl concentration (0.01-1 N), and extraction time (3-8 h) as independent variables, and gelatin protein content (%) and viscosity (mPa.s) as dependent variables. The results showed that the NaOH and HCl concentrations had significant effect on crude protein content and viscosity of whitecheek shark skin gelatin (P < 0.05). Whereas, extraction time up to 8 h had no significant effect on these two properties (P > 0.05). Optimum extraction conditions have been found at 0.92 N NaOH concentration, 0.01 N HCl concentration, and 5.45 h extraction time with 93.1 (%) protein content, and 10.21 (mPa.s) viscosity of the extracted gelatin. The P-value of lack of fit for viscosity was 0.9356 and total regressions P-value was 0.0028 and for protein content were 0.0501 and 0.0346, respectively.