What is next? the greener future of solid liquid extraction of biobased compounds: Novel techniques and solvents overpower traditional ones

Traditional extraction of bioactive compounds from biomass requires large amounts of toxic solvents. As the focus on "green" chemistry increases, efforts are being made to replace these solvents with more environmentally benign alternatives as well as improve the efficiency of the extraction techniques involved. More sustainable solvents such as bio-based solvents, supercritical carbon dioxide, ionic liquids and deep eutectic solvents have been introduced and applied in recent extraction processes. This review summarizes the use of such novel solvents in extraction of bioactive compounds and compares novel to traditional solvents, with a focus on extraction techniques, process parameters and positive and negative aspects of novel solvents. Common and more efficient extraction techniques, such as pressurized solvent extraction (PSE), microwave assisted extraction (MAE), ultrasound assisted extraction (UAE) and aqueous two phase extraction (ATPE), are compared in terms of solute compatibility and extraction efficiency. The positive and negative aspects of the novel green solvents used in these processes are evaluated according to ease of synthesis, environmental impact, toxicology, applicability and efficiency in both common and more novel extraction processes.