Gelation of mixed myofibrillar/wheat gluten proteins treated with microbial transglutaminase

Gluten (Glu) and an acid-extracted protein fraction (AF) from wheat flour were mixed (1:1 ratio) with myofibrillar protein (MP) and treated with microbial transglutaminase (MTGase) to observe the effect on heat-induced gelation. Dynamic rheological properties and thermal denaturation patterns of treated samples were measured, respectively, with an oscillatory rheometer and a differential scanning calorimeter. The storage modulus (G′) of control MP sample (no MTGase), with a value of 533 Pa at end of heating (77°C), was not affected (P > 0.05) by Glu nor by AF. However, mixed protein samples after the MTGase treatment produced higher gel elasticity values that differed (P < 0.05) between samples (1355, 1700 and 1875 Pa at 77°C for MP, MP/AF, and MP/Glu, respectively). The MP sample underwent three endothermic transitions (peaking at 61.5, 68.0, and 78.5°C) during thermal scan. The treatment with MTGase and/or addition of Glu or AF tended to lower the temperature for the first transition but raised the temperature for the third transition, suggesting possible interactions of the muscle with non-muscle proteins.