Inactivation of peroxidase and polyphenoloxidase in coconut water using pressure-assisted thermal processing

The effect of pressure assisted thermal processing (PATP) was evaluated on the inactivation kinetics of polyphenol oxidase (PPO) and peroxidase (POD) and selected quality attributes of coconut water. Coconut water from green young coconuts was treated at 200, 400 and 600 MPa, 40–90 °C, and 60–1800 s of holding time. The activities of PPO and POD were determined using spectrophotometric methods. No enzymatic activity was detected for both enzymes within 300 s at 90 °C/400–600 MPa. The combination of 400 MPa/90 °C/300 s yielded POD and PPO inactivation, and could be used in the industrial development of PATP treated-coconut water. The POD showed to be more pressure-temperature resistant than the PPO in coconut water. The pressure-temperature inactivation kinetics of PPO and POD in coconut water were well described by the Weibull model. The activation energy for the inactivation of POD and PPO were 107–192 and 41–191 kJ mol−1, respectively, while the activation volume varied from −13.2 to 10.2 and −37 to 9.2 cm3 mol−1, respectively. Total phenolic content extractability significantly increased after PATP treatments at all conditions evaluated compared to the control. Low ∆E values of PATP treated coconut water were obtained, indicating imperceptible change of color.