Conventional Methods for Plant Extraction
Conventional Methods for Plant Extraction:
Soxhlet extraction
Soxhlet extraction was first used for lipids, however, it not limited any longer . A dry sample is placed during a thimble, which is further placed during a distillation flask containing the solvent of interest. Siphon unloads the answer back within the distillation flask. the method is repeated until the ultimate compound of interest is extracted
Maceration
Maceration is usually utilized in homemade tonics. it's popular and wont to obtain volatile oil and bioactive compounds. The material is ground into smaller particles and mixed with a solvent. Then the menstruum (solvent) is added to a closed vessel and therefore the liquid is strained to recover the solid residues. The strained liquid is separated from impurities by filtration.
Maceration is an extractive technique that's conducted at temperature . It consists of immersing a plant during a liquid (water, oil, alcohol, etc.) inside an airtight container, for a variable time supported the material and liquid used
Hydro Distillation
Hydro distillation is usually used for essential oils from plants, which may be done via water, steam or direct steam distillation. during this method, the material is boiled in water and direct steam is injected. Indirect cooling condenses the vapour and therefore the separator separates the oil and bioactive compounds from the water. This method isn't used for thermolabile compounds
Non-Conventional Methods for Plant Extraction
There are quite few modern nonconventional methods which are preferred compared to the traditional methods. a number of the key modern methods are supercritical fluid extraction (SFE), pressurized liquid extraction (PLE), Microwave assisted extraction (MAE), Enzyme assisted extraction (EAE), pulsed field extraction (PEF) and Ultra sound assisted extraction (UAE).
Ultra sound assisted extraction (UAE)
Ultrasound passes through a medium by creating cavitation, i.e. compression and expansion. Liquid materials are often exploited using this cavitation effect. UAE facilitates the leaching of organic and inorganic compounds from the plant matrix, by intensifying the mass transfer . Ultrasound extraction is found to be suitable for bioactive compounds from herbal plants. it's effective for achieving efficient mixing, faster energy transfer, reduced thermal gradients and selective extraction.
Pulsed-electric field extraction (PEF)
PEF treatment is reported to be useful for improving the pressing, extraction and diffusion process . PEF mechanism works on the principle of the destruction of cell wall structure for enhanced extraction and decreased extraction time. PEF treatment is applied to enhance the discharge of intracellular compounds by increasing the cell wall permeability . supported the planning of the treatment chamber, PEF process could either be operated in batch or continuous process. PEF treatment parameters like field intensity , specific energy, treatment time, temperature and property of the plant matrix are liable for the effectiveness of the treatment.
PEF treatments at 1kV/cm and 7kJ/kg are wont to extract betanin from beetroots. Moreover, recovery of phytosterols from maize was increased by 33% and isoflavonoids from soybeans were increased by 20% . Application of PEF on grape skins before maceration has been reported to scale back the general time required with improved stability.
Enzyme assisted extraction (EAE)
This method is widely accepted and used because it is novel, non-toxic and non-inflammable. In some plant matrices, phytochemicals are present within the cell cytoplasm and retained by hydrogen or hydrophobic bonding, which aren't accessible by solvent extraction. The addition of specific enzymes like cellulose, amylase, pectinase as a pretreatment enhances the recovery by breaking the cell membrane and hydrolyzing the structural polysaccharides and lipids. Extraction of oils from various seeds are often achieved using enzyme assisted aqueous extraction. The extracted oils were found to contain a better amount of free fatty acids and phosphorus content compared to the traditional methods. Enzyme composition, concentration, particle size and hydrolysis time are considered as key factors of EAE.
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