Diffusion Behavior of Microbial Transglutaminase to Induce Protein Crosslinking in Oil-in-Water Emulsions

Abstract

Food-grade hydrogel particles composed of sodium alginate were used to investigate the diffusion behavior of microbial transglutaminase (mTG) to induce crosslinking of interfacially adsorbed protein. For this purpose, mTG-loaded hydrogel beads were mixed with caseinate-stabilized oil-in-water emulsions, whereas Bradford assay and ammonia measurements were utilized to monitor the enzyme-induced interfacial protein crosslinking. Different alginate (0.5–1.5%) and gelling concentrations (50–500 mM CaCl2) were used to modulate the hydrogel mesh size and number of junction zones. The results indicated that mTG was able to diffuse out of alginate beads. However, a decrease in NH3 concentration with increasing alginate and CaCl2 levels was observed due to the formation of tight and dense bead structures. These results illustrate that the spatial distribution of molecules in complex matrices plays a key role on the enzyme accessibility