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Hydrothermal deglycosylation and deconstruction effect of steam explosion: application to high-valued glycyrrhizic acid derivatives from liquorice

Sui, Wenjie, Zhou, Mengjia, Xu, Yi, Wang, Guanhua, Zhao, Huan, Lv, Xiaoling
Food chemistry 2019
autohydrolysis, bioactive compounds, diffusivity, endothermy, glucuronic acid, glycosidic linkages, glycyrrhetinic acid, glycyrrhizin, licorice, reaction kinetics, thermodynamics
In this work, steam explosion (SE) was exploited as a green and facile process to deconstruct liquorice’s structure and deglycosylate glycyrrhizic acid (GL) to improve conversion and diffusion efficacy of GL and its hydrolyzed products. Results showed SE induced auto-hydrolysis of GL into glycyrrhetic acid 3-O-mono-β-D-glucuronide (GAMG) and glycyrrhetinic acid (GA), by which 30.71% of GL conversion, 5.24% and 21.47% of GAMG and GA formation were obtained. GL hydrolytic pathways were revealed by reaction kinetics and thermodynamics, which possessed complex consecutive and parallel reactions with endothermic, non-spontaneous and entropy-decreasing features. SE referred to cause cleavage of the β-1,3 glycosidic bond in GL which was hydrolyzed to GA as a main product and GAMG and glucuronic acids as minor products. Diffusion of hydrolyzed products was accelerated by raising the diffusion coefficient and shortening equilibrium time by more than 90%. This work provides a sustainable and efficient route for product conversion and function enhancement of bioactive components.