Ionic Liquid-Assisted Extraction in Food Valorization

Ionic liquid-assisted extraction has emerged as a transformative approach in the recovery and upcycling of valuable compounds from food and agro-industrial residues. Unlike conventional organic solvents, ionic liquids (ILs) offer negligible vapour pressure, high thermal stability and tunable polarity, enabling selective dissolution of target antioxidants, pigments, lipids and bioactive peptides. By tailoring the cation–anion pairing, researchers have engineered task-specific ILs that enhance extraction yields while minimising energy input and environmental impact. Integration of ILs into biorefinery schemes facilitates cascade fractionation, in which sequential use of IL-rich and hydrophobic phases enables recovery of multiple product streams—such as pigments and proteins—in a single unit operation. This versatility underpins emerging circular-economy models, where food waste is repurposed into functional ingredients for nutraceutical, cosmeceutical and food-packaging applications. Process intensification strategies, including pressurised-liquid extraction and in-line solid-phase purification, further improve throughput and product purity, paving the way for industrial-scale adoption of greener extraction technologies.

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Innovative platforms combining ionic liquids with auxiliary solvents have delivered significant gains in pigment recovery from marine biomass. One study developed an integrated extraction and fractionation system for brown macroalgae that uses a phosphonium-based IL blended with sunflower oil and water. Operating under mild conditions, this approach achieved extraction yields of nearly 5 mg chlorophyll g⁻¹ and 1.9 mg fucoxanthin g⁻¹ of dry biomass. Subsequent phase separation yielded an oil-free IL-rich aqueous phase, from which over 80 % of the IL was recovered by back-extraction, demonstrating economic and environmental viability through solvent recycling. In another example, pressurised-liquid extraction coupled in-line with solid-phase extraction employed deep eutectic solvents to recover anthocyanins from fruit residues. This platform achieved high extraction efficiency and pigment purity, while the eutectic medium acted as both solvent and stabiliser, enhancing thermal stability and prolonging shelf life of the colourants. Collectively, these advances illustrate how IL-based and IL-inspired solvents can be engineered into continuous, multi-product processes that valorise diverse food by-products with minimal waste generation.

Ionic Liquid-Assisted Extraction in Food Valorization publication trend

The graph below shows the total number of articles in ionic liquid-assisted extraction in food valorization across all publications each year (not limited to Nature Index journals).

Technical terms

Ionic liquid: A molten salt at ambient temperature comprising organic cations and inorganic or organic anions, notable for low volatility and adjustable solvation properties.

Deep eutectic solvent: A mixture of two or more components that forms a eutectic with a melting point lower than that of its individual constituents, often biodegradable and low-cost.

Task-specific solvent: A customised solvent system, typically an ionic liquid or eutectic mixture, designed to interact selectively with particular target molecules.

Pressurised-liquid extraction: A technique using elevated temperature and pressure to enhance solvent penetration and solute solubility in solid matrices.

Solid-phase extraction: A separation method in which solutes are adsorbed onto a solid sorbent and subsequently eluted with a small volume of solvent for purification.

Three-phase partition: A process in which addition of water induces separation into a protein-rich interface between an IL-rich aqueous phase and an immiscible organic phase, enabling simultaneous recovery of proteins and other compounds.

References

1. Extraction and Fractionation of Pigments from Saccharina latissima (Linnaeus, 2006) Using an Ionic Liquid + Oil + Water System. ACS Sustainable Chemistry & Engineering (2021).
2. Combining eutectic solvents and pressurized liquid extraction coupled in-line with solid-phase extraction to recover, purify and stabilize anthocyanins from Brazilian berry waste. Green Chemistry (2023).