There are many different methods used to extract active compounds from plants including maceration extraction, percolation, and Soxhlet. Depending on the needs and the laboratory set-up it is possible to choose the most suitable method.
What is maceration?
The maceration extraction process is a simple one. First, the drug (which is either whole or powdered) gets put into a container with a solvent. It will then be left at room temperature for a minimum of three days. After the proper amount of time, the resulting mixture is separated from the plant matrix through filtration. [1] The left over solid matter can be extracted multiple time to maximize the yield and can be pressed to recover as much extract as possible.
What is percolation?
When it comes to getting ingredients for tinctures, percolation is the most common method used. A funnel-shaped object with openings at both ends called a percolator is used in the process. The whole plant is placed in a sealed container with a solvent and is then left to sit for around four hours. After this, the ingredients are placed into the percolator with more solvent and the top is closed. It’s left to sit for around one day and then the bottom of the percolator is opened, allowing the liquid to drip out the bottom.
What is Soxhlet extraction?
In Soxhlet extraction The drug is finely powdered and placed into a porous bag made of filter paper. It is then placed into the Soxhlet extractor that is an apparatus containing different chambers with a heat source below it. An extractant will drip into the main chamber causing the liquid level of the main chamber to rise. Once the main chamber of the Soxhlet apparatus rises high enough, it will reach a siphon tube that will drip down into a flask at the bottom. [2] This process is repeated continuously for an exhaustive extraction of active compounds from the plant matrix, with high efficiency and employing low amount of solvent.
What makes them different?
Maceration extraction is a simple and quick process that can be repeated fairly easily on a consistent basis. Percolation extraction is also quick, but requires additional equipment and typically more solvent to be used. Soxhlet extraction is by far the most efficient method and it can be done on a large scale operating continuously with high extraction yields and low solvent use.
References:
[1] Handa SS, Singh J. Extraction Technologies for Medicinal and Aromatic Plants. International Centre For Science And High Technology. 2008; pages 22-24, 67-68. [Times cited = 92]
[2] Redfern J, et al. Using soxhlet ethanol extraction to produce and test plant material (essential oils) for their antimicrobial properties. J Microbiol Biol Educ. 2014;15(1):45-46. doi:10.1128/jmbe.v15i1.656 [Journal impact factor = 1.67] [Times cited = 182 ]
