High pressure thermal processing of pears: Effect on endogenous enzyme activity and related quality attributes

摘要

The effect of high pressure-thermal (HPT) processing (600 MPa, 20-100 degrees C) on the activity of pear enzymes and related quality attributes was investigated. HPT processing at 20 degrees C for 5 min resulted in 32%, 74% and 51% residual activities of polyphenol oxidase (PPO), peroxidase (POD) and pectin methylesterase (PME), respectively. Increasing processing temperature to 40 and 60 degrees C reduced the level of PPO and POD inactivation, with the maximum residual activities of 64% and 123%, respectively observed after 3-min treatments at 40 and 60 degrees C. Overall, HPT at 20 to 60 degrees C had minimal effect on quality, although enzymatic browning was observed upon air exposure. HPT at 80 to 100 degrees C caused almost complete inactivation of PPO and POD with 90% and 92% inactivation respectively after 3-min processing at 100 degrees C, which reduced browning upon air exposure. Nevertheless, the lowest texture retention of 22% was observed under this condition.