Continuous-flow manothermosonication treatment of apple-carrot juice blend: Effects on juice quality during storage

Abstract

The effect of manothermosonication (MTS) treatment on quality of apple-carrot juice blends during storage was examined in comparison with a high temperature-short time (HTST) treatment. The juice blend (90% apple, 10% carrot) with a pH of 4–4.5 was treated by MTS in a custom-designed sonoreactor (20 kHz and 100% amplitude) at 50 and 60 οC and 200 kPa for 30s or 60s. The quality attributes of the control and the treated juices were compared on days 0, 7, 14, and 21, including brix, turbidity, color, viscosity, pH, titratable acidity (TA), total phenolic content (TPC), and antioxidant capacity. Changes in trace elements of the juice samples were monitored using X-ray fluorescence (XRF) spectrometry. The antioxidant activity of the MTS samples right after treatment and during storage was significantly higher than that of the HTST-treated. No significant differences on TPC and antioxidant capacity were found between the MTS-treated and the control during storage. The TA, Brix, and turbidity of the MTS samples decreased after treatment and during storage whereas a gradual increase in pH was observed in stored juice samples. A better retention of trace elements was observed in the MTS-treated samples than in the HTST ones.