Mild‐thermal and high pressure processing inactivation kinetics of polyphenol oxidase from peach puree

AbstractThis study has investigated the inactivation of polyphenoloxidase (PPO) in peach puree during thermal (50–60 °C, 2–30 min) and combined high pressure‐mild thermal treatment (HPMT) (200–600 MPa, 25–45 °C, and 2–23 min). HPMT resulted immediately after treatment in an increase in PPO activity up to 66.50% at 200 MPa and 45 °C compared with the untreated samples. The reaction order (nth) of PPO thermal inactivation was 1.951 (0.1 MPa, 50–60 °C) and 0.953 for the HPMT treatment (200–600 MPa, 25–45 °C). Fractional kinetic models were applied in PPO thermal (~89% labile fraction, 11% stabile fraction) and HPMT inactivation (up to ~67% stabile fraction at 200 MPa, 25 °C). The activation energy estimated for the thermal inactivation in 50–60 °C range at 0.1 MPa was 148.26 kJ/mol, while for the HPMT inactivation varied from 82.31 kJ/mol at 300 MPa to 226.16 kJ/mol at 500 MPa. A third order polynomial model described the PPO inactivation by HPMT.Practical applicationInactivation of polyphenoloxidase (PPO), enzyme responsible for browning is a mandatory condition for maintaining quality of the processed fruits. As this enzyme is generally known to display variable thermal and/or barostability, depending on the type of food matrix, kinetic data are required to optimize the processing parameters. The data on peach puree PPO and the models provided in the current study could help producers to identify the optimum peach processing condition necessary for the inactivation of PPO by high pressure‐mild thermal treatment, leading to the extension of puree shelf life. However, methods for limitation of the oxygen presence in the peach puree mixtures should also be employed during processing and storage.