Kinetic study of polyphenols extraction from olive (Olea europaea L.) leaves using instant controlled pressure drop texturing

The aim of this investigation is to study the impact of the technology of instant controlled pressure drop: "DIC" on the kinetics extraction of olive leaf (Olea europaea L.) polyphenols. The conditions of extraction were: ethanol 95%, temperature: 55 degrees C and ratio r = 40 g g(-1) dry basis for 3 h. The extraction kinetics of total polyphenols content (TPC) of DIC-treated and untreated leaves were performed according to the method of Folin-Ciocalteau. The ultra-performance liquid chromatography (UPLC) was used to study the extraction kinetics of seven phenolic compounds of olive leaves: apigenin-7-glucoside, hydroxytyrosol, luteolin-7-glucoside, oleuropein, tyrosol, vanillic acid, and verbascoside. DIC-assisted solvent extraction allowed reducing the extraction time from 120 to 15 min while increasing the extracted yields. Phenomenological analysis of extraction kinetics was determined through the two-stage Coupled Washing/Diffusion CWD kinetic model. DIC texturing could, in favorable cases, increase the starting accessibility and systematically the internal effective diffusivity for phenolic compounds. (C) 2016 Elsevier B.V. All rights reserved.