Thermosonication: a potential technique that influences the quality of grapefruit juice

Thermosonication (TS) is an emerging nonthermal processing technique used for the liquid food preservation and is employed to improve the quality and acceptability of grapefruit juice. In this study, fresh grapefruit juice samples were subjected to TS treatment in an ultrasonic cleaner with different processing variables, including temperature (20, 30, 40, 50 and 60 degrees C), frequency (28kHz), power (70%, 420W) and processing time (30 and 60min) for bioactive compounds, inactivation of enzymes pectin methylesterase (PME), peroxidase (POD) and polyphenolase (PPO) and micro-organisms (total plate count, yeasts and moulds). The micro-organism activity was completely inactivated in the treatment (60 degrees C for 60min). The TS treatment at 60 degrees C for 60min exposure reduced PME, PPO and POD activity by 91%, 90% and 89%, respectively. Results indicate that the advantages of TS for grapefruit juice processing at low temperature could enhance the inactivation of enzymes and micro-organisms and it can be used as a potential technique to obtain better results as compared to alone.