Surface hydrophobicity, reactive and total sulfhydryl groups, circular dichroism, and storage modulus (G') revealed that unfolding of actomyosin began at 35°C, while aggregation took place at 45°C. Optimum temperature of crude transglutaminase (TGase) was found at 37 and 55°C and pH 7-7.5. TGase activity was reduced from 99 unit/g dry weight in mince to 47 unit/g dry weight after screw pressing. Gels incubated at 25°C for 4 h and 40°C for 3 h showed an increased force at failure. Degradation of myosin heavy chain (MHC) was evident when incubation time at 40°C was extended. Iodoacetic acid (IAA) was found to be the most effective TGase inhibitor. Autolytic degradation of threadfin bream was highest at 60°C. Salt had no effect on autolytic activity. Force at failure and deformation of surimi gels decreased as incubation time at 60°C was prolonged, corresponding to a decrease of MHC.
ASJC Scopus subject areas
- Food Science