Cyclodextrin-assisted extraction of phenolic compounds: Current research and future prospects

Background: Phenolic compounds (PC) have received much attention due to their potential bioactive and functional properties. The common solvents used to extract PC from natural sources are organic solvents, which may contribute to environmental pollution and cause health problems in persons. The advent of green chemistry is forcing scientists to explore greener solvents. Recently, cyclodextrins (CDs) in aqueous solution have been applied as extraction solvents for PC. Scope and approach: The extraction role of CDs is mainly attributed to their capacity to form inclusion complexes with PC. This review provides an overview of the key factors involved in the extraction process: type of CD, CD concentration, extraction temperature and time, and extraction technique. Advantages of the CD-assisted extraction of PC are summarized and future research needs are also proposed. Key findings and conclusions: The addition of CD to the water improves the extraction efficiency for PC and shortens the extraction time, and the obtained PC extract present better antioxidant activity. Not only is the removal of CD unnecessary, but also the presence of CD favors the preparation of the PC extract in a solid state, which are very beneficial since they will be expected to be used either to fortify foods or as a food supplement on an industrial scale. However, further studies are required to evaluate the possibility of combining CDs with other extraction methods, such as high hydrostatic pressure, pulsed electric fields, negative pressure cavitation and pressurized liquid extraction, to extract PC from natural materials.