Ultrasound-assisted intensified removal of dextran from sugarcane juice using dextranase

Abstract

The present work demonstrates the effectiveness of dextranase-based ultrasound-assisted enzymatic treatment in reducing dextran content in sugarcane juice. Effect of various parameters such as enzyme loading (0.01 U – 0.07 U) treatment duration (5–20 min), temperature (40–70°C), pH (4−7), ultrasonic power (20–80 W), and duty cycle (20–50 %) on the dextran removal was studied. The scalability and efficiency of several ultrasonic reactors (US bath, hexagonal, and horn reactors) including the variation of frequencies (22, 33, and 48 kHz) using hexagonal reactor were also examined. Ultrasound-assisted treatment at 50°C, pH 5, a 10-min time, 30 % duty cycle, and 40 W power produced the best results for the highest dextran elimination (93 %). By contrast, only 63 % of the dextran was removed using the traditional method. Ultrasonic horn demonstrated the highest efficiency (93 %) attributed to higher power density followed by hexagonal reactor and ultrasonic baths (81 % and 72 %, respectively). Furthermore, the best results for dextran removal were obtained with single-frequency ultrasound at 22 kHz; whereas higher and combination frequencies resulted in decreased effectiveness because of wave interference and denaturation of the enzyme. The work has clearly demonstrated the effectiveness of ultrasound also elucidating the effect of reactor type and frequency for the first time.