Reaction kinetics of hydrothermal hydrolysis of hesperidin into more valuable compounds under supercritical carbon dioxide conditions

A kinetic model and reaction mechanism of hydrothermal hydrolysis of hesperidin aided with supercritical carbon dioxide were elucidated. Experiments were carried out at 25 MPa, reaction temperatures of 110-140 degrees C and reaction time of 1-4 h. Results were presented in terms of the concentration change (with time) of the major components namely hesperidin, hesperetin-beta-glucoside and hesperetin. Experimental results showed that pressurized carbon dioxide could serve as a catalyst for the hydrothermal degradation of hesperidin that follows first-order rate kinetics. The pathways for the degradation reaction compose of complex reactions. The one involves consecutive reactions that take hesperetin-beta-glucoside as an intermediate product followed by its degradation to hesperetin. Parallel to that is a reaction that directly cleaves the glycosidic bond of hesperidin to form hesperetin. The kinetic parameters of the hydrolysis reaction were estimated by least squares approximation methods, and the proposed model fitted well with the experimental data. The values of activation energies calculated based on Arrhenius equation may suggest that the cleavage of rhamnosidic bond takes lesser energy than the cleavage of glycosidic bond of hesperidin. (c) 2011 Elsevier B.V. All rights reserved.