Optimizing processing conditions for milk coagulation using the hot wire method and response surface methodology

Abstract

To evaluate the relationship between the factors affecting coagulation, the hot wire method was used for direct measurements of the renneting milk process as well as a central composite design with 3 factors: Rennet concentration (x1), renneting pH (x2), and temperature (x3). Second-order models for maximum voltage (Y1), time at maximum voltage (Y2), and coagulation time (Y3) were employed to generate response surface contours. Optimum conditions for cutting time were found with x1 = 0.0278 R.U./mL milk, x2 = 6.60, and x3 = 35°C, for which the responses were Y1 = 2854 ± 171 μV, Y2 = 14.08 ± 3.04 min, and Y3 = 7.16 ± 1.12 min. No significant differences (p > 0.01) were found between the 3 responses obtained in the experiment and the ones predicted by the models. The use of the objective and non-destructive monitoring of curd formation and the response surface methodology can be recommended to optimize milk coagulation.