Background and Objectives: the healthier effects of protein sources, especially plant sources instead of red meat for the production of protein-based products such as burgers have been proven. However, the lack of proper interaction between proteins of plant source causes poor physical properties of product. Microbial transglutaminase enzyme, results in improvement of  the textural properties of protein products by formation of covalent bonds and casein is one of the best substrates for this enzyme. The aim of this study is to evaluate the effect of different concentrations of enzyme and sodium-caseinate on the physicochemical characteristics of veggie burger.

Materials and Methods: Microbial transglutaminase (MTGase, 0-0.75%) and sodium-caseinate (SC, 0-2%) were added to veggie burger formulation. The solubility of proteins and water-holding capacity were measured and in order to investigate the protein-protein interaction, the SDS-PAGE electrophoresis was applied.

Results: Addition of SC and MTGase significantly increased the water holding capacity and decreased solubility of the protein (P<0.05). Sodium-caseinate in both levels and the enzyme at less than 0.75% alone had no significant effect on the water holding capacity (P>0.05). The addition of MTGase alone or in combination with SC significantly decreased the solubility of the protein. SDS–PAGE analysis showed that burger dough did not form specific bands on SDS-PAGE. Therefore, in order to investigate the precise effect of enzyme, mixture of soy and enzyme was added to electrophoresis gel. Results revealed significant reduction in density of soy bands after adding MTGase and elimination of basic protein subunit B3.

Conclusions: MTGase combined with sodium-caseinate resulted in improvement of the water holding capacity, interaction of proteins and the solubility reduction of protein and thus enhanced the physical properties of veggie burgers.