Gelation properties of chicken myofibrillar protein isolate (MPI) and the effect of microbial transglutaminase (MTG) were studied using a dynamic oscillatory rheometer and a texture analyzer. Final heating temperature had a great impact on gel stiffness and the maximum gel stiffness was obtained at 95 degrees C. pH and ionic strength also influenced gel stiffness and the maximum gel stiffness was achieved at pH 6, 0.9 M NaCl: however, less stiff gels were formed in 0.6 and 1.2 M NaCl. In the MPI concentration range of similar to 0.5-5%, a positive correlation was observed between gel stiffness or gel peak force and MPI concentration. When MTG was included at levels of similar to 0 to 12-15 U. positive linear relations were found between gel stiffness or peak force and MTG levels. However, negative correlations for these parameters were observed at higher MTG concentrations. When MTG level was greater than 15 U. gel stiffness or peak force tended to decrease. The improvement in gel strength or gel peak force for the MPI with inclusion of MTG suggested that some epsilon (gamma-glutamyl) lysine (G-L) crosslinking occurred among myofibrillar molecules. Thus, MTG is useful in improving gelation properties of heat-induced MPI gel and provides new opportunities to expand the utilization of low value meat in muscle foods. (C) 2011 Elsevier Ltd. All rights reserved.