Sustainable Supramolecular Deep Eutectic Solvents based extraction for bioactive phenolic compounds recovery from olive pomace

Abstract

Olive oil industries produce a large quantity of by-product, such as wastewater and olive pomace, which are characterized by a high concentration of phenolic compounds, which can be recovered and eventually reused in cosmeceutical and nutraceutical fields. The recovery of bioactive molecules from waste is usually carried out by common of organic solvents. To respect the principles of green chemistry, other solvents such as Deep Eutectic Solvents (DESs) have been evaluated. DESs are sustainable solvents involved in sample preparation. Recently, DESs have also been evaluated as extraction solvent with the addition of β-cyclodextrins (β-CDs) which are cyclic oligosaccharide molecules obtained from the enzymatic degradation of starch, and their characteristics allow them to be selective toward certain analytes. These innovative solvents, called Supramolecular Deep Eutectic Solvents (SupraDESs), seem to be excellent green solvents for the extraction of phenolic compounds and are a sustainable alternative to conventional solvents. The aim of this work was to develop and optimize an analytical procedure for the extraction of phenolic compounds from olive pomace, using a SupraDES composed by ammonium acetate - lactic acid (in a molar ratio of 1:7) with the addition of a certain amount of β-cyclodextrins as extraction solvent. The optimized extraction procedure, defined through Box-Behnken Design, is based on the best extraction time of 22 min, temperature of 43°C, solid-to-liquid ratio of 1:48 (g:mL) and β-CDs concentration of 1.8 % (w/w). The qualitative profile of the extracted phenolic compounds was determined through high performance liquid chromatography coupled with mass spectrometry.