Hydrophobic deep eutectic solvents in the food sector: Focus on their use for the extraction of bioactive compounds

Hydrophobic Deep Eutectic Solvents (HDESs) represent a novel kind of solvent. While several studies investigated their properties, just a few dealt with their use for extracting and recovering bioactive compounds from raw materials, wastes and by-products, even if HDESs might represent an interesting alternative when producing pharmaceuticals, foodstuffs and cosmetics. Furthermore, their use may contribute to realizing more sustainable green processes. This review focuses on HDESs, with particular emphasis on Natural HDESs, discussing their properties and uses, highlighting their role as extractants in food applications, both from an analytical and processing point of view, and underlining the positive and negative aspects. While of prospective interest, currently the use of HDESs at industrial level remains a challenge, with several aspects needing further investigation. In order to scale-up the process, more research should focus on key issues, such as solute recovery, solvent recycling and extraction yields, as well as potential health hazards.