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Abstract Natural ingredients are currently attracting growing interest for industrial applications such as functional food, nutraceuticals, cosmetics, and pharmaceuticals. A key point is the societal acceptance for the naturally occurring
compounds which are believed to be safer to humans and environment than artificial
compounds. Polyphenols are one of the most interesting plant substances which are
carrying many biological activities. Thousands of phenolic compounds have been
identified, isolated, and selected from the plant kingdom including terrestrial and
marine sources. A challenge concerns the development of efficient and green technologies for the extraction of plant and algal polyphenols. Ionic liquids have been
successfully evaluated, but they are facing strong issues related to their cost, sourcing, and green nature, precluding any industrial development. Being cheaper and
eco-friendly, deep eutectic and natural deep eutectic solvents have a great potential
as solvents for the extraction of polyphenols. The ability of deep eutectics to form
hydrogen bonds is particularly of interest for the selective extraction of polyphenols
since these compounds are generally rich in hydrogen bond donor groups.
Here we propose a comprehensive review of the use of deep eutectic solvent for
polyphenol extraction processes, with more than 100 references published over the
last decade. Despite the large possible combination of components for preparing
deep eutectics with tunable properties, choline chloride-based eutectics are the most
largely used extractant media. Important parameters including sampling, sample
preparation, water content in deep eutectic solvent, extraction duration, and temperature along with methodology to account with all these interacting parameters
are examined. These parameters have been put in perspective with extraction technologies. All are specifically considered in terms of extraction performances when
using deep eutectic solvents. Here again, it turns out that only a few of the available
technologies have been indeed evaluated with deep eutectic solvents, leaving ample
perspectives for improvement in the field of polyphenol extraction in the near future.
Finally, identification and quantification technologies are also discussed since they
are also a key aspect in the process. The possibility of using deep eutectic solvents
for a given application without having to extract the polyphenols also appears to be
a very promising prospect, strengthened by the longer preservation of their antioxidant properties in deep eutectics.
Keywords Polyphenols · Deep eutectic solvents · Natural deep eutectic solvents ·
Hydrogen bond · Extraction · Maceration · Selectivity · Ultrasound · Microwave ·
Antioxidant properties
Abbreviations
ABTS 2,2′-Azino-bis(3-ethyl-benzothiazoline-6-sulfonic) acid
BBD
Box-Behnken design
DES
Deep eutectic solvents
DPPH 2,2-Diphenyl-1-picrylhydrazyl hydrate
FRAP Ferric reducing-antioxidant power
L. Percevault et al.
Abstract Natural ingredients are currently attracting growing interest for industrial applications such as functional food, nutraceuticals, cosmetics, and pharmaceuticals. A key point is the societal acceptance for the naturally occurring
compounds which are believed to be safer to humans and environment than artificial
compounds. Polyphenols are one of the most interesting plant substances which are
carrying many biological activities. Thousands of phenolic compounds have been
identified, isolated, and selected from the plant kingdom including terrestrial and
marine sources. A challenge concerns the development of efficient and green technologies for the extraction of plant and algal polyphenols. Ionic liquids have been
successfully evaluated, but they are facing strong issues related to their cost, sourcing, and green nature, precluding any industrial development. Being cheaper and
eco-friendly, deep eutectic and natural deep eutectic solvents have a great potential
as solvents for the extraction of polyphenols. The ability of deep eutectics to form
hydrogen bonds is particularly of interest for the selective extraction of polyphenols
since these compounds are generally rich in hydrogen bond donor groups.
Here we propose a comprehensive review of the use of deep eutectic solvent for
polyphenol extraction processes, with more than 100 references published over the
last decade. Despite the large possible combination of components for preparing
deep eutectics with tunable properties, choline chloride-based eutectics are the most
largely used extractant media. Important parameters including sampling, sample
preparation, water content in deep eutectic solvent, extraction duration, and temperature along with methodology to account with all these interacting parameters
are examined. These parameters have been put in perspective with extraction technologies. All are specifically considered in terms of extraction performances when
using deep eutectic solvents. Here again, it turns out that only a few of the available
technologies have been indeed evaluated with deep eutectic solvents, leaving ample
perspectives for improvement in the field of polyphenol extraction in the near future.
Finally, identification and quantification technologies are also discussed since they
are also a key aspect in the process. The possibility of using deep eutectic solvents
for a given application without having to extract the polyphenols also appears to be
a very promising prospect, strengthened by the longer preservation of their antioxidant properties in deep eutectics.
Keywords Polyphenols · Deep eutectic solvents · Natural deep eutectic solvents ·
Hydrogen bond · Extraction · Maceration · Selectivity · Ultrasound · Microwave ·
Antioxidant properties
Abbreviations
ABTS 2,2′-Azino-bis(3-ethyl-benzothiazoline-6-sulfonic) acid
BBD
Box-Behnken design
DES
Deep eutectic solvents
DPPH 2,2-Diphenyl-1-picrylhydrazyl hydrate
FRAP Ferric reducing-antioxidant power
L. Percevault et al.