Enzymatic cross-linking of caseins with microbial transglutaminase (mTGase) is a prominent example of protein polymerization and shows high potential for techno-functional applications in dairy processing. In many cases, the beneficial effects of the cross-linking were linked to the size of the large casein polymers generated by mTGase, and therefore high-resolution size separation techniques coupled to appropriate detectors are essential for a detailed molecular characterization.
This application note shows the capabilities of asymmetric flow field flow fractionation (AF4) in combination with differential refractive index measurement plus static and dynamic light scattering (AF4-MALS-DLS) for a gentle separation and investigation of caseins enzymatically cross-linked with mTGase. Using this approach, we have gained essential knowledge regarding the modus operandi of mTGase on size and conformation of caseins.
