Kinetics of ultrasound-assisted flavonoid extraction from agri-food solid wastes using water/glycerol mixtures

Abstract

Red grape pomace (RGP) and onion solid wastes (OSW) were used as raw material to produce flavonoid-enriched extracts, using ultrasound-assisted solid-liquid extraction. The extraction medium used was composed of water and glycerol and under the conditions used the extraction of flavonoids from both materials was shown to obey first-order kinetics. Maximum diffusivities (De) values were 4.01 ×10-11 and 2.35 ×10-11 m2 · s-1, for RGP and OSW extraction, respectively, while the corresponding activation energies (Ea) were 14.00 and 15.23 kJ. mol-1.