Enhancement of transglutaminase-induced protein cross-linking by preheat treatment of cows’ milk: A statistical approach

Optimization of heat treated milk towards protein cross-linking induced by transglutaminase was carried out. Capillary electrophoresis was employed to study the extent of cross-linking under different preheating temperatures (70–90 °C) and times (15–60 min). The experiments were arranged according to a central composite statistical design (32+centre points). Response surface methodology was used to assess factor interactions and empirical models regarding relative peak area (%) of individual protein (αs2-casein, αs1-casein, αs0-casein, κ-casein, β-casein A1, β-casein A2, α-lactalbumin and β-lactoglobulin) and total αs-caseins, total β-caseins and whey proteins (sum of α-lactalbumin and β-lactoglobulin). Multi-response optimization was also performed on the total αs-caseins, total β-caseins, κ-casein and whey proteins data set of the factorial design. The desirability function was the statistical tool employed in this multi-optimization step. The optimum preheating conditions that maximized the cross-linking reactions catalyzed by transglutaminase were achieved within 60 min at 84.5 °C.