Extraction techniques for plant-based bio-active compounds

Abstract

Bio-active compounds include terpenoids, alkaloids, nitrogen-containing compounds, organosulfur compounds, and phenolics. Plant-based bio-active compounds show antimicrobial activity, anti-inflammatory activity, immunostimulatory activity, anticancer activity, antioxidant activity, etc. Due to higher benefits of bio-active compounds, they have been used for the manufacturing of food supplements and food additives and as an alternative to drugs and an ingredient for foods to increase their functionality. The extraction is the main step to obtain a desired bio-active compound from the plant materials. Since bio-active compounds are synthesized in small quantities in plants and embedded within the plant matrix, sometimes complexed with other compounds in the plant, their proper extraction method is very crucial. There are two main extraction methods used for bio-active compounds: classical or conventional methods and nonconventional methods. The classical methods include soxhlet extraction, maceration, infusion, percolation, digestion, decoction, steam, and hydrodistillation. The disadvantages of conventional methods include higher consumption of organic solvents with higher purity, higher cost, lower extraction efficiency, long processing time, and higher temperature. Therefore, as an alternative to classical extraction methods, nonconventional methods have been applied extensively so far. Nonconventional methods were referred to as green technologies. Since energy and organic solvent consumption are reduced, those methods can be regarded as beneficial to the environment. The most important methods are ultrasound-, enzyme-, microwave-, and pulsed electric field-assisted extraction, pressurized liquid extraction, and supercritical fluid extraction. The extraction yields of bio-active compounds are strongly bound on the extraction method, physicochemical properties of the plant material, extraction solvent, temperature, pressure, and time. The present chapter focuses on the technologies used for the extraction of plant-based bio-active compounds and comparison of advantages and disadvantages of the methods and summarizes the recent advances in this field.