244
Herein, the recent literature data about the extraction of polyphenols in deep
eutectic solvent and natural deep eutectic solvent is thoroughly reviewed. First, a
section describes the structures and properties of plant and algal polyphenols. Then
definition, structure, and main physicochemical properties of deep eutectic solvent
are discussed, highlighting their expected potential as extractant media toward
polyphenols.
The extraction processes are implemented according to general steps which are
illustrated in Fig. 7.2. For each of these steps, the nature and impact of deep eutectics is considered, ranging from the selection of plant matrix, mixing with deep
eutectic solvent, extraction methodology to identification and purification of targeted bioactive compounds. All the deep eutectic solvents commonly used for polyphenol extraction are reported, showing that they are mainly based on choline
chloride. Key parameters involved in the extraction processes are reviewed, namely,
sampling, sample preparation, temperature, water content, duration, etc. A focus is
made on the extraction technologies, demonstrating that only few of the available
technologies are indeed employed. Finally, a section is dedicated to the polyphenol
recovery in the deep eutectic solvent extracts, showing a promising prospect of
keeping deep eutectic solvent as a part of polyphenol formulation. A last point of
importance regarding the quantification and the identification of polyphenols is
examined. We will then end the review with a critical conclusion with
perspectives.
0
5
10
15
20
25
30
35
Flavonols
Flavones
Isoflavones
Flavanones
Flavanols
Anthocyanidins
Stilbenes
Hydroxycinnamic
acids
Hydroxybenzoic
acids
Total polyphenols
Total flavonoids
"True"
polyphenols
Fig. 7.1 Number of articles as a function of types of polyphenols targeted in extraction studies
using deep eutectic solvents and natural deep eutectic solvents. “True” polyphenols denominate a
category of polyphenol polymers like condensed or hydrolyzable tannins. Note that flavones and
flavonols are the most investigated polyphenol families
L. Percevault et al.
Herein, the recent literature data about the extraction of polyphenols in deep
eutectic solvent and natural deep eutectic solvent is thoroughly reviewed. First, a
section describes the structures and properties of plant and algal polyphenols. Then
definition, structure, and main physicochemical properties of deep eutectic solvent
are discussed, highlighting their expected potential as extractant media toward
polyphenols.
The extraction processes are implemented according to general steps which are
illustrated in Fig. 7.2. For each of these steps, the nature and impact of deep eutectics is considered, ranging from the selection of plant matrix, mixing with deep
eutectic solvent, extraction methodology to identification and purification of targeted bioactive compounds. All the deep eutectic solvents commonly used for polyphenol extraction are reported, showing that they are mainly based on choline
chloride. Key parameters involved in the extraction processes are reviewed, namely,
sampling, sample preparation, temperature, water content, duration, etc. A focus is
made on the extraction technologies, demonstrating that only few of the available
technologies are indeed employed. Finally, a section is dedicated to the polyphenol
recovery in the deep eutectic solvent extracts, showing a promising prospect of
keeping deep eutectic solvent as a part of polyphenol formulation. A last point of
importance regarding the quantification and the identification of polyphenols is
examined. We will then end the review with a critical conclusion with
perspectives.
0
5
10
15
20
25
30
35
Flavonols
Flavones
Isoflavones
Flavanones
Flavanols
Anthocyanidins
Stilbenes
Hydroxycinnamic
acids
Hydroxybenzoic
acids
Total polyphenols
Total flavonoids
"True"
polyphenols
Fig. 7.1 Number of articles as a function of types of polyphenols targeted in extraction studies
using deep eutectic solvents and natural deep eutectic solvents. “True” polyphenols denominate a
category of polyphenol polymers like condensed or hydrolyzable tannins. Note that flavones and
flavonols are the most investigated polyphenol families
L. Percevault et al.