Effect of thermosonication on enzymatic oxidation and physicochemical properties of soursop (Annona muricata) pulp

Abstract

Soursop is an exotic tropical fruit with marked commercial importance. However, its post-harvest presents losses of around 30%. The objective of this research was to study the effect of thermosonication (TS) on physicochemical properties and enzymatic oxidation of soursop pulp. Four treatments were evaluated: control (0 min), ultrasound at 20 °C (US20), 40 °C (US40), and 60 °C (US60) for 25 minutes. Concentration of vitamin C, and peroxidase (POD) and polyphenoloxidase (PPO) inactivation in the soursop pulp, were assessed. The results indicate a loss of vitamin C of 2.63%; 13.16% and 28.95% for temperatures at 20, 40 and 60 °C, respectively. On the other hand, partial inactivation of 48.41%; 69.83% and 74.24% of POD, and 56.38%; 74.47% and 81.91% of PPO enzymes were achieved at temperatures of 20, 40 and 60 °C, respectively. Finally, it was concluded that ultrasound combined with heat (TS) can inactivate POD and PPO enzymes in the soursop pulp, achieving consid-erable retention of vitamin C.