Degradation kinetics of myosin heavy chain of Pacific whiting surimi

Pacific whiting surimi paste was ohmically heated to investigate degradation of myosin heavy chain (MHC) caused by endogenous proteinase over a range of 40-85 degrees C and 0.5-35 min. Degradation was best described with an apparent reaction order of 1.4. Changes of degradation rate increased with temperature and reached a maximum at 57 degrees C. Then, rate of MHC degradation decreased with higher temperature and reached a minimum at 75 degrees C. E-a values of activation and inactivation zone were 142.3 and 83.1 kJ/mol, respectively. Generally, failure shear stress and shear strain increased linearly with MHC content. Proteolytic degradation of actin exhibited the same trend as that of MHC but at a slower rate. The synergistic effect of actin in the gelation of whiting surimi was predominant at greater than or equal to 75 degrees C.