High-intensity ultrasound-assisted recovery of cinnamyl alcohol glycosides from Rhodiola rosea roots: Effect of probe diameter on the ultrasound energy performance for the extraction of bioactive compounds

High-intensity ultrasound (HIUS) energy performance was evaluated using different probe diameters (10 and 20 mm) and specific energies (0.5, 1.0, 3.0, and 5.0 kJ/g) to recover rosavin and rosin from Rhodiola rosea roots. Also, intensified HIUS process conditions (5, 10, 15, and 20 kJ/g) assisted by a cold bath were studied. HIUS energy performance depended on probe diameter at the same nominal power. The larger diameter probe was more energy-efficient, however, the smaller diameter had more ultrasonic intensity (W/cm(2)). The diameters evaluated did not influence the extraction yields, however, the increase of the HIUS specific energy from 0.5 to 5.0 kJ/g increased phenolic compounds content, antioxidant activities, and rosavin and rosin yields. The HIUS process intensification confirmed that the main extraction mechanism was diffusion and the role of the ultrasound was to increase the diffusion coefficients by increasing the turbulence in the liquid medium due to acoustic cavitation. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.