Enzymatic protein cross-linking transglutaminase

The weak physical forces that hold together self-assembled nanoparticles are, of course, susceptible to disruption under the influence of thermodynamic and/or mechanical stresses. Hence some workers have investigated ways to reinforce nanoscale structures via covalent bonding. For instance, improved stability of protein nanoparticles, in particular, casein micelles, can be achieved by enzymatic cross-linking with the enzyme transglutaminase, which forms bonds between protein-bound glutamine and lysine residues. By this means native casein micelles can be converted from semi-reversible association colloids into permanent nanogel particles (Huppertz and de Kruif, 2008). 

Different textures can be obtained through enzymatic cross-linking of meat proteins by means of enzymes such as transglutaminase and thrombin. Details of the action... 

Cho, Y.H., Shim, H.K., and Park, J. (2003). Encapsulation of fish oil by an enzymatic gelation process using transglutaminase cross-linked proteins. J. FoodSci. 68, TlYl-212 i. 

A second possibility to increase the functionality of spray-dried emulsions is to build up a specific structure with desired functionality at the oil-water interface. Enzymatic cross-linking of proteins at the oil-water interface can increase the stability of emulsions. Cross-linking of a-lactalbumin at the interface of an emulsion increased the physical stability [28]. Kellerby et al. [29] investigated the influence of network formation through transglutaminase on the oxidation stability of caseinate-based fish oil emulsions. The authors showed that cross-linking increases the cohesiveness of the proteins at the interface but not lipid oxidation in liquid emulsions. Data from our own research showed that also in spray-dried microcapsules transglutaminase cross-linked proteins do not act as additional barrier (data not published). 

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