APPLICATION OF BOX-WILSON CENTRAL COMPOSITE EXPERIMENTAL DESIGN TO OPTIMIZE THE PROTEOLYTIC ACTIVITY IN MILK BY LACTOCOCCUS LACTIS LCL STRAIN

Abstract

In this work, the individual and interactive effects of temperature and pH on the proteolytic activity of Lactococcus lactis LCL strain in milk were studied by quadratic Response Surface Methodology. The effects of the selected variables have been analysed using a Central Composite Design and the maximum response (proteolysis rate) under the optimum values of variables and of a satisfactory fit model was realized. The mathematical relationship of the proteolytic activity on the two significant independent variables can be approximated by a nonlinear polynomial model. Predicted values were found to be in a good agreement with experimental values (R² = 0.937) demonstrating the good significance of the model. The result of optimization predicted by the model has shown that the maximal result for the proteolysis rate revolved around of 43.7 ± 1.4 % at the optimal condition (30°C and pH 7).