Transglutaminase Shows Better Functionality on High Digestible, High Lysine Sorghum-Wheat Composite Dough and Bread, Compared to Normal Sorghum-Wheat Composites

Abstract

Highly digestible high-lysine (HDHL) sorghum-wheat composites have previously been shown to produce better composite dough and bread compared to normal sorghum-wheat composites. This study aimed to test whether improved HDHL lines can provide further enhanced functionality through the effects of transglutaminase (TG) enzyme to improve dough rheological properties. Sorghum-wheat composite doughs were made using HDHL and normal sorghum flours at substitution levels of 10, 20, and 30%, with and without 0.15% TG. Rheological properties of dough were tested using a mechanical spectrometer at 0.05% strain amplitude (within the linear viscoelastic region) over a 0.01- 50 rad/sec frequency range. A more elastic system was observed in HDHL sorghum-wheat composites above 10% substitution levels compared to normal sorghum-wheat composite dough. Addition of TG to HDHL sorghum-wheat composites resulted in a decrease in phase angle values at all substitution level, indicating that TG increased the dough elasticity. However, TG did not change viscoelastic properties of normal sorghum-wheat composites. Bread from HDHL sorghum-wheat composites had significantly higher (P

Methods for the Modification and Evaluation of Cereal Proteins for the Substitution of Wheat Gluten in Dough Systems

“…These parameters complement critical information related to the capacity of doughs to retain gas. Tunçil et al obtained both G values to calculate the complex modulus (G*), where lower values indicate weaker doughs [ 70 ]. Another studied parameter is the loss tangent (tan δ), obtained from dividing G” by G’.…”

“…Another enzyme studied in gluten-free cereals is transglutaminase, a transferase that catalyzes the formation of iso-peptide bonds including ε-(γ-glutamyl) lysine, a bond formed between the γ-carboxamide group in glutamine and the ε-amine of lysine (acyl acceptor), as shown in Figure 5 [ 83 , 84 ]. Although it is not a study of a gluten-free system, Tunçil et al used TG in a wheat formulation containing highly digestible high lysine (HDHL) sorghum, a genotype with an altered folded protein body that makes kafirin more accessible to digestible enzymes [ 70 ]. TG addition increased the bread firmness up to 50% in doughs containing 20 and 30% sorghum substitution; however, the specific volume was not affected by the treatment.…”