Transglutaminase and tyrosinase as potential cross-linking tools for the improvement of rheological properties of gluten-free amadumbe dough

Gluten-free bread remains of poor quality despite efforts to amend gluten-free flours with ingredients such as hydrocolloids and proteins. Enzymatic modification of the proteins in dough may result in polymers that mimic gluten. This research investigated the effects of transglutaminase and tyrosinase on the rheological properties of amadumbe dough. Tyrosinase oxidation resulted in a 7.7-39.4% decrease in dough-free amine, and a 16.8-46.3% decrease in the dough thiol content as activity was increased from 0 to 80 U g(-1) flour. Transglutaminase treatment decreased the dough-free amino groups by 10-38.1% as activity was increased from 0 to 2 U g(-1) flour. Evidence of tyrosinase and transglutaminase-mediated cross-linking was provided by relevant model reactions monitored by mass spectrometry. An increase in dough G ' and G '' showed that both transglutaminase and tyrosinase improved dough viscoelasticity. The increase in the viscoelasticity of the dough potentially improves carbon dioxide retention during proofing.