A review of ultrasound-assisted extraction for plant bioactive compounds: Phenolics, flavonoids, thymols, saponins and proteins.

Plant bioactive compounds are important sources for the development of food, nutraceutical, cosmetic, and pharmaceutical products. Ultrasound-assisted extraction is one of the promising methods in the extraction of plant bioactive compounds. The ultrasonic-assisted extraction is accepted as a green extraction technique due to its high performance with less solvent and time consumption, as well as suitable for thermo-sensitive compounds. The objective of this paper is to review the recent advancement of ultrasound-assisted extraction for bioactive compounds from plant material. The mechanism and advantages of ultrasound-assisted extraction are discussed, particularly focusing on the extraction of bioactive compounds such as phenolics, flavonoids, thymols, saponins and proteins. Previous studies on the optimization of extraction variables are systematically reviewed to reveal their significant contribution to the yield and quality change of bioactive compounds. Ultrasonic technology has also been combined with other processing technologies to improve food quality, stability, safety and security. Therefore, ultrasound-assisted extraction is effective to recover bioactive compounds from plant materials and enhance the processing of food industries.