Thermal properties of crude papain and crude peroxidase from domestic papaya were investigated. The crude extract of papaya was inactivated at the temperature range of 60°∼90℃ at pH 7.0 and the rest of the activities of papain and peroxidase were determined, respectively. The heat inactivation of papain and papaya peroxidase was biphasic at low temperature.
For the thermal inactivation of papain extract, the enthalpy of activation was 91.4 kJ/㏖, the entropy of activation, -49.6 J/㏖·K, and the free energy of activation, 108.5 kJ/㏖. The activation energy for the inactivation of papaya peroxidase was 168.5 kJ/㏖, the entropy of activation, 200.4 J/㏖·K and the free energy of activation, 99.7 kJ/㏖.
The thermal stability of papain showed that it has a possibility for use as a meat tenderizer. It was also discussed that papaya peroxidase could be more suitable as a biochemical criteria for heat treatment than papaya catalase.
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