Non-thermal combined treatments in the processing of açai (Euterpe oleracea) juice

Abstract

Quality parameters of açai juice processed with ultrasound-assisted, ozone and the combined methods were analyzed in this work. Two ultrasound energy densities (350 and 700 J·mL^-1) and two ozonization times (5 and 10 min with 1.5 ppm) were analyzed for pure açai juice and 8 different treatments (2² complete factorial). To evaluate the quality parameters of the juice, physical-chemical analyzes such as pH, titratable acidity, cloud value, non-enzymatic browning, rheology, antioxidant activity (DPPH and ABTS), phenolic compounds, anthocyanins, enzymatic activity (peroxidase and polyphenol oxidase) and microbial counts (mesophilic bacteria, molds and yeasts) were conducted. The treatments with ozone were better for microbial inactivation and the ultrasound for enzymatic inactivation. In general, the use of non-thermal methods can be a good alternative for the processing of açai juice.

Keywords: Antioxidant activity; Enzymatic activity; Fruit juice processing; Ozonization; Ultrasound-assisted.