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Medicinal plants are a source of molecules with precise pharmacological effects, as an alternative to drugs with great side effects, and to satisfy the growing needs of using natural products. Among the most important aspects in the production of extracts, there are certainly the appropriate choice of plant material, the availability of the raw material, the feasibility of the crops and the precise botanical identification of the plant, in addition to perfect conservation and storage. The conditions of collection and transformation of the raw material influence the quality of the final extract. It is necessary to know the part of the plant at harvest, the time and the shape of the cut. The fresh material must be treated immediately to avoid deterioration, discarding the damaged or damaged parts of the plant and washing with water, if necessary.
After carefully evaluating the quality of the plant and collecting it following precise indications, the raw material is crushed for a long time, kept in contact with an alcoholic or non-alcoholic solvent, to begin the maceration process, which can last up to fifteen days. After this time the mixture is filtered, the insoluble material is washed away with the same solvent and the filtrates are mixed to concentrate the extract. Another process used for the production of extracts is percolation, which differs from maceration due to the type of support used. If in the maceration the herbs sell in a closed container to remain in contact with the solvent, in the percolation, the container is different and allows the dripping. In this case the solvent is renewed continuously, maintaining a constant concentration gradient while the herbs are pressed.
Depending on the degree of extraction concentration, the extracts can be classified into:
It is important to establish the extraction parameters to obtain the standardization of the process that will guarantee the quality, performance, safety and efficacy of the medicinal product. Among these parameters we see the careful chemical nature analysis of the plant material: knowing the characteristics of the metabolite or the compound to be extracted. Solvent selection: define the selectivity of the solvent used, evaluate the solid-liquid ratio. Analyze the shape and size of the solids because the best percolation is obtained with a greater contact surface between the drug and the solvent, therefore the liquid solvent must be able to penetrate well into the fibers to optimize the extraction. Also the temperature is important, because it can increase the percolation of waste materials. The extraction time and the agitation of the extractor determine the optimal values for a greater yield of the product. With a longer extraction time, the solvent will have a greater chance of extracting concentrated material from the plant. Once the extraction process is complete, the vegetable product obtained must be characterized in terms of: active substances, density, residual solvents, total solids, pH, microbiological control and total volume. Solid-liquid separation is performed to remove drug residue after extraction. Today almost all technological processes in the chemical and pharmaceutical sector include solid-liquid separation in the list of fundamental processes for the industry in the sector. The choice of a separator useful for this purpose is a much more complex task than the selection of the equipment used in the extraction process.
Each time the extraction and separation phase have been completed, part of the extraction solvent is removed to increase the solids content in the extract. This process is performed at reduced pressure by decreasing the heating temperature required for solvent output; the rotary evaporator is a good alternative for working in the laboratory and is widely used while similar systems that are used on an industrial scale.
Other methods can also be used, such as the precipitation of the active ingredient combined with filtration phases, liquid-liquid extraction, and others.
To preserve the natural components of the plant extracts drying methods are used for their preparation in the form of powder (dry extract). In these processes it is very important to evaluate the following variables: concentration of solids, drying temperature, humidity, pressure, flow rate and work speed, and the use of inert additives as adjuvants to improve drying performance.
DIY dry extracts
But how can you resist the temptation to experiment with the home extraction procedure?
What seems very complicated at an industrial level, like expensive and complex machinery, can be reproduced, in small, in one's own house, using common objects.
Here is a small recipe for a homemade extract:
add a liter of alcohol to the perfectly clean and finely chopped herbs, in a glass jar or in a bottle. Alcohol can be replaced with vodka or gin. Alcohol is an excellent homemade solvent because it allows a simpler extraction and protects against possible fungal attacks. The container should remain at rest for at least four weeks. After this time the extract is ready to be filtered and stored in dark glass bottles or containers.
Obviously the better the quality of the herbs used, the better the quality of the final extract. Using herbs from your own garden or harvested from organic crops is certainly a recommended choice. During the extraction process, any pesticide and fungicide residues are also extracted which are dispersed together with the solvent and are combined with the final extract, in high concentrations; for this reason we must take into account which herbs to use, in order to prevent a home remedy from ancient tradition from becoming a concentrate of harmful substances. Another consideration to make, in the case of homemade extract, is the dosage to be taken. Since the concentration of homemade extracts is not as precise as those produced in the laboratory, it is always good to underestimate the intake and follow the herbal information available in any herbal medicine.