High hydrostatic pressure processing of peach puree with and without antibrowning agents

High hydrostatic pressure (HHP) (103 to 517 MPa) was applied for selected times (5 to 25 min) on peach puree with and without the addition of antibrowning agents (1000ppm ascorbic acid or 300ppm cysteine). Polyphenoloxidase (PPO) activity was assessed before and after HHP processing. Peach purees were stored at 3C for 13 days and then at 22C for 15 additional days. A Z(P) value of 224 MPa, in a range from 207 to 517 MPa of pressure, was obtained for peach puree without the addition of antibrowning agents. PPO activation at 103, 207 and 310 MPa or inhibition at 414 and 517 MPa was observed in peach purees containing added ascorbic acid. More than 50% inactivation of PPO was observed after adding cysteine to the peach puree and 99% inhibition was observed after 517 MPa of pressure at the experimental times. ne higher the pressure treatment and the longer the treatment time for inactivating PPO, the less the discoloration of the peach puree with and without antibrowning agents during storage at low temperatures.