Maceration is an extractive technique that is conducted at room temperature. It consists of immersing a plant in a liquid (water, oil, alcohol, etc.) inside an airtight container, for a variable time based on the plant material and liquid used.
Before being processed, the plant must be properly washed and separated from foreign material such as topsoil, pebbles or rocks, weeds, and materials non-suitable for extraction. The plant material can be used fresh or dry based on the desired product.
In order to increase contact between the plant material being extracted and the liquid (solvent), the plant needs to be cut into small pieces.
The pieces should not be too big, otherwise the solvent will not be able to penetrate the innermost cells. They also should not be reduced to powder; that would result in losing the volatile active ingredients (essential oils) contained inside the plant, and also losing the difficult separation by filtration of the plant material from the liquid used once maceration is completed.
The solvent must be chosen based upon the chemical nature of the compounds contained within the plant. Solubility and the desired use of the extraction should be considered when choosing the solvent. That is, recognizing their solubility and the desired use of the extraction. Generally, alcohol is the most used substance because it is able to extract a greater part of the molecules (active ingredients) contained within the plant, including molecules which are hydrophilic, soluble in water, or lipophilic and therefore, soluble in oil or other organic solvents.
One uses a vegetable oil when one wants to isolate only the lipophilic components (fats), while water is used to extract only hydrophilic ingredients.
Plant extracts that can be obtained through maceration:
INFUSION in which the plant, fresh or dried, is left to macerate in a vegetable oil (olive oil, better if extra-virgin, or seed oil). A fresh or dried plant is left to macerate in a vegetable oil.
TINCTURES and MOTHER TINCTURES are obtained by maceration of a plant in a mixture of water and alcohol.
GLYCERIC MACERATES: The liquid is constituted from a mixture of equal quantities of ethyl alcohol, water, and glycerin. The parts of the plant that are processed through maceration in this mixture are, in general, embryonic tissues such as buds and young sprouts.
GLYCOLIC EXTRACTS are obtained after maceration of the plant in propylene glycol. This solvent is for external use only.
The infusion and the glycolic extracts are for external use. Tinctures, mother tinctures, and macerated glycerides, rather, are for both external and internal uses.
It is recommended to mix the plant inside the container at least once a day for the entire time of maceration to make sure that the solvent penetrates all of the plant material.
At the end of the time, one proceeds with the filtration of the macerated mixture to separate the plant material from the liquid.
The residue of the plant, being still saturated with solvent, needs a final press at the end in order to recover all of the product.