Pressurized liquid extraction for the determination of bioactive compounds in plants with emphasis on phenolics

Pressurized liquid extraction (PLE) is considered an advanced extraction technique because it can save time and reduce solvent consumption compared to traditional extraction methods. It is a solid-liquid extraction performed at high temperatures and high pressure. Considering the importance of enhancing the value of by-products or waste products and the increased use of high-temperature extraction methods for bioactive compounds, this work aims to provide a comprehensive review regarding PLE, focusing on thermolabile plant compounds such as phenolic compounds. Not only traditional PLE approaches are described, but also subcritical water applications that reduce the consumption of organic solvents, as well as online approaches to improve the separation of compounds. Finally, the PLE technique is compared with other conventional and non-conventional methods used in the literature for the same bioactive compounds. PLE can provide significant recovery of bioactive compounds (i.e., phenolic compounds, carotenoids, chlorophylls, and anthraquinones) from various plant extracts, with the possibility of obtaining green extracts for analytical purposes and various industrial applications.