Recent extraction techniques for natural products: microwave‐assisted extraction and pressurised solvent extraction

Abstract

In the last 10 years there has been an increased interest in using techniques involving microwave-assisted extraction and pressurised solvent extraction in analytical laboratories. This review gives a brief overview of both methods, and reports on their application to the extraction of natural products. The influence of parameters such as the nature of the solvent and volume, temperature, time and particle size of the matrix is discussed. Through numerous examples, it is demonstrated that both techniques allow reduced solvent consumption and shorter extraction times, while the extraction yields of the analytes are equivalent to or even higher than those obtained with conventional methods.

Feasibility Study and Structural Analysis of Cellulose Isolated from Rice Husk: Microwave Irradiation, Optimization, and Treatment Process Scheme

“…As the solvent ratio increased, the pretreatment efficiency also increased. This result reflects that the chosen solvent has a high dielectric constant and strongly absorbs microwave irradiation, though the selectivity of the isolation and the medium interaction with microwave irradiation could be adjusted by manipulating the solvent mixture (Kaufmann and Christen 2002).…”

“…Unlike conventional techniques, microwaves heat the sample simultaneously and uniformly. In cellulose isolation processes, the advantage of the microwave method is the disruption of weak hydrogen bonds, which is promoted by dipole rotation (Kaufmann and Christen 2002).…”

Techniques for extraction of bioactive compounds from plant materials: A review

“…PLE has also been used for the extraction of bioactive compounds from marine sponges (Ibañez et al, 2012). Applications of PLE technique for obtaining natural products are frequently available in literature (Kaufmann and Christen, 2002). Additionally, due to small amount organic solvent use PLE gets broad reorganization as a green extraction technique (Ibañez et al, 2012).…”

“…Now a days, for extraction of polar compounds, PLE is also considered as a potential alternative technique to supercritical fluid extraction (Kaufmann and Christen, 2002). PLE is also useful for the extraction of organic pollutants from environmental matrices those are stable at high temperatures (Wang and Weller, 2006).…”

“…Non-conventional methods, which are more environmental friendly due to decreased use of synthetic and organic chemicals, reduced operational time, and better yield and quality of extract, have been developed during the last 50 years. To enhance overall yield and selectivity of bioactive components from plant materials, ultrasound (Vinatoru et al, 1997;Ghafoor et al, 2011), pulsed electric field (Toepfl et al, 2006), enzyme digestion (Gaur et al, 2007), extrusion (Lusas and Watkins, 1988), microwave heating (Kaufmann and Christen, 2002), ohmic heating (Lakkakula et al, 2004), supercritical fluids (Marr and Gamse, 2000;Lang and Wai, 2001;Meireles and Angela, 2003;Wang et al, 2008;Ghafoor et al, 2010Ghafoor et al, , 2012, and accelerated solvents (Kaufmann and Christen, 2002;Smith, 2002) have been studied as non-conventional methods. At the same time conventional extraction methods, such as Soxhlet is still considered as one of the reference method to compare success of newly developed methodology.…”