The inactivation of peroxidase (POD) and polyphenol oxidase (PPO) in red beet extract with high pressure carbon dioxide (HPCD) was investigated. HPCD treatment at 37.5 MPa for POD and 22.5 MPa for PPO (55 °C, 60 min) resulted in a reduction of their activities by approximately 86% and 95%, respectively. Compared with thermal treatment (55 °C), the decimal reduction time (D) of POD and PPO was reduced from 555.56 min to 74.63 min and 161.29 min to 38.31 min, respectively, by the HPCD treatment. The inactivation process followed first-order kinetics (R2 > 0.84, p < 0.05) with D values declining with the rise of pressure and temperature. The activation energy of the inactivation was reduced by the HPCD treatment from 92.54 kJ/mol to 68.63 kJ/mol and 57.06 kJ/mol to 53.58 kJ/mol for POD and PPO, respectively. Analysis of the kinetic parameters of the inactivation showed that both POD and PPO were less sensitive to pressure changes under supercritical than subcritical conditions.
Liu, X., Gao, Y., Peng, X., Yang, B., Xu, H., & Zhao, J. (2008). Inactivation of peroxidase and polyphenol oxidase in red beet (Beta vulgaris L.) extract with high pressure carbon dioxide. Innovative Food Science and Emerging Technologies, 9(1), 24-31. https://doi.org/10.1016/j.ifset.2007.04.010