Effect of preheat treatment on the transglutaminase-catalyzed cross-linking of goat milk proteins

The susceptibility of the individual goat's milk proteins to cross-linking with transglutaminase was investigated. Results from capillary gel electrophoresis showed that a heat treatment of milk before reaction with transglutaminase enhanced the reactivity of milk proteins towards protein cross-linking. The results of this paper suggest that the specificity of transglutaminase varied with the type of milk proteins. κ-casein was more susceptible to cross-linking than α- and β-casein. However, no significant differences between both caseins were observed. Furthermore, only in heated milk, β-lactoglobulin was significant cross-linked by transglutaminase, while preheated and unheated α-lactalbumin was susceptible to enzymatic cross-linking. Finally, an optimization strategy based on desirability functions together with experimental design was used to optimize the preheating conditions (temperature and time) of goat's milk that maximized the cross-linking reactions catalyzed by transglutaminase.