Effect of Dense Phase Carbon Dioxide on Inactivation of Polyphenol Oxidase and Peroxidase in Hami Melon Juice

Abstract

Inactivation of polyphenol oxidase (PPO) and peroxidase (POD) in hami melon juice by treatment with dense phase carbon dioxide (DPCD) was investigated. DPCD treatment (60min, 35MPa 65°C), caused 79% and 81% loss in PPO and POD activities, respectively. The inactivation dynamics followed the first-order reaction kinetics. Higher pressures or temperatures resulted in higher inactivation constants. The treatment time needed for 90% inactivation and the activation energies for PPO and POD decreased in the presence of DPCD, compared with a 65°C thermal treatment. Pressure sensitivity at 65°C was also investigated. The results proved that DPCD was effective for inducing enzyme inactivation in hami melon juice.