Optimization of foaming properties of sludge protein solution by 60Co γ-ray/H2O2 using response surface methodology

• Effects of 60Co γ-ray/H2O2 on foaming properties of sludge protein were studied.
• Response surface methodology and Box-Behnken experimental design were applied.
• 60Co γ-ray/H2O2 method can improve foaming properties of protein solution.

Response surface methodology and Box-Behnken experimental design were used to model and optimize the operational parameters of foaming properties of the sludge protein solution by 60Co γ-ray/H2O2 treatment. The four variables involved in this research were the protein solution concentration, H2O2, pH and dose. In the range studied, statistical analysis of the results showed that selected variables had a significant effect on protein foaming properties. The optimized conditions contained: protein solution concentration 26.50% (v/v), H2O2 concentration 0.30% (v/v), pH value 9.0, and dose 4.81 kGy. Under optimal conditions, the foamability and foam stability approached 23.3 cm and 21.3 cm, respectively. Regression analysis with R2 value of 0.9923 (foamability) and 0.9922 (foam stability) indicated a satisfactory correlation between the experimental data and predicted values (response). In addition, based on a feasibility analysis, the 60Co γ-ray/H2O2 method can improve odor and color of the protein foaming solution.