The activity of polyphenoloxidase (PPO) treated by acidic pH and mild thermal processing was found to be closely related to the conformational changes. Weakly acidic environment (pH 4.0–6.0) resulted in reversible inhibition of activity and slight changes in the conformation, and refolding of PPO was observed after readjusting pH to 6.8. At pH lower than 4.0, PPO activity was strongly inhibited with great unfolding in conformation and all changes were irreversible. Acidic environment increased the susceptibility of PPO to thermal treatment, and greater changes in activity and conformation of PPO were observed under the combined treatment of acidic pH and mild thermal treatment. Besides, the inactivation of PPO induced by thermal treatment followed a biphasic kinetic model, and acidic pH increased the inactivation rate of labile and stable PPO. The combination of acidic pH and mild thermal processing expected to avoid the nutritional loss and sensory damage in fruits and vegetables caused by severe acid or temperature.

发现通过酸性pH和温和的热处理处理的多酚氧化酶（PPO）的活性与构象变化密切相关。弱酸性环境（pH 4.0-6.0）导致活性的可逆抑制和构象的细微变化，将pH值重新调节至6.8后，PPO会重新折叠。在低于4.0的pH值下，PPO活性被强烈抑制，构象极大地展开，并且所有变化都是不可逆的。酸性环境增加了PPO对热处理的敏感性，在酸性pH和温和热处理的联合处理下，PPO的活性和构象发生了更大的变化。此外，热处理引起的PPO失活遵循双相动力学模型，酸性pH增加了不稳定而稳定的PPO的失活率。