Monogioudi et al. investigated the enzymatic crosslinking of β-casein isolated from milk. In the study both a novel tyrosinase as well as well-known transglutaminase were used. Transglutaminase is an enzyme capable of crosslinking proteins via lysine and glutamine residues. This enzyme has been extensively studied on different food matrices including milk products. Tyrosinase is an oxidative enzyme, known to catalyze the oxidation of the phenolic ring of tyrosine residues to the corresponding quinones which then in turn can create crosslinks between proteins. About 25 % of the milk proteins are β-casein. β-casein contains lysine, glutamic acid and tyrosine amino acids and is thus a potential substrate for these two different types of enzymes.