Extraction optimization of pepsin-soluble collagen from eggshell membrane by response surface methodology (RSM)

•RSM was used to investigate the effect of extraction process variables on the PSC from egg shell membrane.•Central composite design was used to study the extraction process.•Experimental values are close agreement with predicted values.•The experimental value of PSC yield varied from 14.8% to 30.1%. Response surface methodology (RSM) was used to investigate the effect of extraction-process variables on pepsin-soluble collagen (PSC) from eggshell membrane. A central composite design (CCD) was employed for experimental design and analysis of the results to obtain the best possible combination of NaOH concentration (X1: 0.4–1.2mol/l), alkali treatment time (X2: 6–30h), enzyme concentration (X3: 15–75U/mg) and hydrolysis time (X4: 12–60h) for maximum PSC extraction. The experimental data obtained were fitted to a second-order polynomial equation using multiple regression analysis and analyzed by appropriate statistical methods. According to the results, optimum extraction conditions were as follows: NaOH concentration of 0.76mol/l, alkali treatment time of 18h, enzyme concentration of 50U/mg and hydrolysis time of 43.42h. The experimental extraction yield under optimal conditions was found to be 30.049%, which is in good agreement with the predicted value of 30.054%.