Effect of ultrasonic treatment on enzyme activity and bioactives of strawberry puree

The aim of this study was to evaluate the impact ultrasound (US) at different frequencies (20, 370, and 583 kHz) power levels (35 48 W) on residual activity (RA) peroxidase (POD) polyphenol oxidase (PPO) in strawberry puree. Total anthocyanin content (TAC), total phenolic (TPC), ferric ion reducing antioxidant (FRAP) trolox equivalent capacity (TEAC) were also assessed. Results compared with untreated, thermally treated 40 °C (control) pasteurized (90 °C) POD PPO RA significantly (P < 0.05) reduced, whilst there a significant increase TAC (5%–19%) all US-treated samples comparison untreated controls. US 20 kHz increased TPC (9%) FRAP (6%) puree, whereas effect (48 these parameters insignificant > 0.05). Pasteurization inactivated PPO, however, decreased dramatically (14%), (17%) (9.5%) These findings suggest that is promising novel non-thermal food technology can be tailored improve quality puree by inactivating enzymes responsible for deterioration maintaining bioactive compounds.