Effect of sonication on soursop juice quality

Soursop juice was submitted to sonication at amplitude levels ranging from 20 to 100 % of the total input power (500 W) at constant frequency of 19 kHz for different times (2–10 min). Response surface methodology based on a central composite design was applied to investigate the effect of ultrasound on polyphenol oxidase (PPO) residual activity, temperature increase, color, ascorbic acid and phenolic compounds. After processing, the PPO activity in the juice was reduced and color changes were subtle. A good retention of phenolic compounds was obtained at higher intensity. Ascorbic acid content was found to be higher in most of the samples treated. The higher the ultrasound intensity and the juice exposure time, the higher its final temperature. An optimum set was chosen and the final product was submitted to a sensorial test. The sonicated sample had a good acceptance. The technology could be suitable as an alternative to thermal and other treatments that results in quality loss.