Transglutaminase effects on low temperature gelation of fish protein sols

Myosin polymerization and formation of epsilon-(gamma-glutamyl)lysine linkages were quantified in Alaska pollock surimi gels which contained no additive (control), or a commercial microbial transglutaminase (MTGase). As preincubation (''setting'') time at 25 degrees C was increased, the gel strength of control and 0.2% MTGase-added samples increased, with greater increases at higher MTGase levels. SDS-PAGE and HPLC analyses showed increasing nondisulfide polymerization and epsilon-(gamma-glutamyl)lysine dipeptide content, with increasing setting time and/or added MTGase. Content of epsilon-(gamma-glutamyl)lysine dipeptide correlated with gel strength (shear stress) and shear modulus at failure (G(f)) for these gels. Higher stresses were measured in samples containing 0.2% MTGase than in controls at corresponding levels of epsilon-(gamma-glutamyl)lysine dipeptide, indicating that rate of myosin polymerization may affect ultimate gel strength.