| Polyphenoloxidase (PPO) plays a role in enzymatic browning in fruits and vegetables and, in many products, must be inactivated in order to produce a high quality product. High pressure processing (HPP) is a promising approach for producing more “fresh-like” products than conventional thermal process. PPO is pressure resistant and may be the cause of unacceptable color in some products produced by HPP. The goal of this study is to better understanding the inactivation of PPO and to develop a means of inactivating PPO during HPP.; Results for chemically treated potatoes showed sulfite caused the greatest inactivation of PPO compared to EDTA and protease inhibitors. The inactivation of PPO is pH dependent. Some PPO survived applications of pressure alone. The activation or inactivation of PPO that occurred was dependent on PPO sample preparations, PPO environment (i.e., inhibitor, pH, phosphate buffer) and multiple cycles of pressure. Complete inactivation of PPO occurred in samples immersed in pH 4 at very high pressure (700 MPa) with or without inhibitor. No retention of PPO activity was seen in the application of pressure cycle at 1.5 min for 10th cycle at 700 MPa, but the resulting product still had an unacceptable color. Activation of PPO during HPP caused unacceptable amounts of browning to occur before PPO was inactivated by the multiple pressure cycles. Treatments to potatoes in addition to HPP are required in order to produce an acceptable product. |
