Phenolic compounds from virgin olive oil obtained by natural deep eutectic solvent (NADES): effect of the extraction and recovery conditions

Abstract

Environmentally friendly natural deep eutectic solvents (NADES) have been shown to efficiently extract a wide range of phenolic compounds from virgin olive oil (VOO). The objective of this work was to optimize the yield of olive oil phenols extracted by NADES based on choline chloride/xylitol (Xyl/ChCl). Different extraction and recovery conditions were investigated, including the effect of different extraction operating parameters (temperature, time, VOO:NADES ratio) and subsequent recovery conditions (XAD resin height, wash-water and eluent volume and pH). The highest concentration of phenols (555.36 mg/kg VOO) was obtained from extraction at 40º C for 1 h, with a 1:1 ratio, using an adsorption resin XAD-16 with bed height of 10 cm, 250 mL acidified wash-water and 300 mL EtOH 100% as eluent. No statistically significant loss of the sum of phenolic compounds was observed when compared with the concentration values obtained by direct analysis in HPLC without the elimination of NADES. Additionally, a sequential desorption with different concentration of ethanol was used to determine the effect of the solvent concentration on polyphenol yield. Polar compounds, such as hydroxytyrosol and tyrosol, were recovered at 81.7 % and 83.6 %, respectively; however, 100% ethanol was required for the complete elution of oleacein (3,4-DHPEA-EDA) and oleocanthal (p-HPEA-EDA). In this paper we present an effective process for the extraction of polyphenols from VOO by NADES for direct analysis in HPLC and for the recovery and concentration of polyphenols by removing the solvent (NADES) with no losses of yield and solvent recycling.

Deep Eutectic Solvents for the Extraction of Bioactive Compounds from Natural Sources and Agricultural By-Products

“…An exhaustive revision of the literature shows that, apart from vegetables, plants, fruits or agricultural by-products, other natural matrices have also served as source of valuable compounds and as occur with previous sources, the use of NADESs as extraction solvents has been also carried out. In this sense, oils obtained from citric, cereals, olives, and palm [40][41][42][43][44][45][46] have been the products most widely evaluated using DESs, although flour [47], eggs [48] and milk [49] as well as nonagricultural by-products [10,50] have been also investigated. As can be seen in Table 3, the studies were focused on the search of different and varied types of molecules including phenolic compounds [40][41][42]46], flavonoids [40,43], terpenoids [10,42,44], proteins [48], lignans [45] or minerals [50].…”

“…[47] In this kind of application, again ChCl was the preferred HBA combined with alcohols, organic acids, sugars or urea [40,41,[43][44][45][46]50] although other quaternary ammonium salts combined with alcohols [42,47,48], lactic acid combined with glucose [49] or terpenes (menthol) together with myristic acid [10] have been also applied. In all cases, natural components were used, thus the application of NADESs has been the choice in the studies developed so far in this area.…”

Latest Insights on Novel Deep Eutectic Solvents (DES) for Sustainable Extraction of Phenolic Compounds from Natural Sources

“…It contains at least 36 structurally different phenolic compounds, and studies have proven that olive oil’s phenolic compounds display positive effects on human health [ 112 ]. Rodríguez-Juan et al [ 79 ] extracted phenolic compounds from virgin olive oil with a ChCl:xylitol aqueous DES through agitation in a water bath, followed by solvent removal using a XAD-16 resin column. The DES was washed with water in the column, and the phenolics were eluted with ethanol, thus recycling the DES.…”

Extraction of Biocompatible Collagen From Blue Shark Skins Through the Conventional Extraction Process Intensification Using Natural Deep Eutectic Solvents

“…Representing all the green chemistry principles, the biocompatibility of NADES is of great interest when it comes to the pharmaceutical, medical, and food industries ( Liu et al, 2018 ). Among the natural molecules, citric acid and xylitol have been widely used in forming NADES and have already been studied to extract phenolic and volatile aromatic compounds, metals, among others ( Bajkacz and Adamek, 2017 ; Cunha and Fernandes, 2018 ; González et al, 2018 ; Aryati et al, 2020 ; Guinet et al, 2020 ; Oomen et al, 2020 ; Santana et al, 2020 ; Silva et al, 2020 ; Fanali et al, 2021 ; Osowska et al, 2021 ; Rodríguez-Juan et al, 2021 ). Although only a few published studies are related to their combined use, NADES composed of citric acid and xylitol, previously and extensively characterised by the works of Grønlien et al and Guinet et al, present a promising potential for extracting biopolymers ( Grønlien et al, 2020 ; Guinet et al, 2020 ).…”