Hydrolysis kinetics and electrophoresis pattern of the impact of the kiwi fruit actinidine on different proteins of Rainbow Trout meat

Different methods are used to improve the quality of meat, one of which is to add proteolytic enzymes to the meat and tenderize it, thereby increasing the solubility of its proteins. Physical and chemical methods tenderize the meat by reducing or degrading myofibrillar proteins and connective tissues. In this study, the impact of kiwi protein on the physicochemical properties of Rainbow Trout meat was investigated. 2 cm cube pieces of fish meat were marinated in 20 ml of kiwi protein with the activity of 0.9 u/ml for a duration of 2, 4, 6, 8, 24, 48, 72, and 96 hours and then kept at 4 ± 1˚C. Afterwards, the actinidine enzyme was inactivated at 60°C for 10 minutes and the specimens were evaluated. The results showed that the hydrolysis of the muscle and the released amino acids significantly reduced the treatments pH in comparison to the control sample. The duration of enzyme activity significantly influenced the decomposition of fish meat proteins, increased the solubility and degree of hydrolysis, and reduced the peptide chain average length. The protein enzyme kinetic equation was suitable for modeling the enzymatic reaction of fish meat; the influence of kinetic parameters on enzyme and substrate variables was further investigated. Changing the concentration of the enzyme and substrate did not affect the parameter b but it positively influenced the parameter a. The results of SDS-PAGE electrophoresis showed that the kiwi enzyme enhanced the fish meat tenderness by affecting the sarcoplasmic and myofibrillar proteins.