Effect of thermosonication on polyphenol oxidase inactivation and quality parameters of soursop nectar

In the present study, the effect of thermosonication on polyphenol oxidase (PPO) inactivation and quality parameters of soursop nectar was evaluated [at 24 kHz, average temperature of 34, 44 and 54 °C, acoustic energy density (AED) (1.1, 1.2 and 1.4 W/mL) and processing time (2, 6 and 10 min)]. Classical thermal pasteurization (65 °C, 30 min) reduced 81% PPO activity and ascorbic acid content by 36% in comparison to fresh nectar. All treatments with thermosonication at 34 or 44 °C decreased the initial PPO activity between 34 and 67%; while treatments at 54 °C decrease PPO activity among 91 and 99%. Also these last treatments had 90% retention of ascorbic acid, without significant changes in quality parameters. In conclusion, thermosonication can be an excellent alternative to total PPO inactivation, without changes in the quality of soursop nectar.