Temperature and pH Affect Transglutaminase-Catalyzed "Setting" of Crude Fish Actomyosin

Dynamic rheological properties of actomyosin from two species (Alaska pollock, Atlantic croaker) were monitored during preincubation (setting) at 25°C and 37°C. followed bv nronrammed (l°C/min) cookinn to 77°C. Added guinea pig liver transgluianase enhanced gelation, as indicated by increases in both storage modulus (G′) and percentage of polymerized myosin heavy chain (MHC). In the presence of added transglutaminase maximum G′ and MHC polymerization occurred at the same conditions of pH and temperature which were optimum for setting of surimi pastes. This suggested that the transglutaminase-mediated setting reaction in surimi was constrained more by the conformation of the substrate (i.e., myosin) than by that of the enzyme.