One of our company’s main areas of research and development is the extraction of plant compounds, such as active ingredients, terpenoids and fatty acids, that have a potential application in the pharmaceutical, nutraceutical and dermocosmetic sectors.
In particular we are investigating the applicability of supercritical fluid extraction, by using, for example, CO2, in conjunction with the Italian company Separeco Srl. A supercritical fluid is any substance in conditions of temperature and pressure above its critical point. A supercritical fluid has typical properties which give it the generic definition of “a hybrid between a liquid and a gas”, as it can spread like a gas and dissolve materials like a liquid. Supercritical fluids have various advantages in the extraction processes; an example being that, as they act as a liquid, theyfacilitate the dissolution of the solutes while their behavior as a gas allows good penetration and easy separation of the matrix; this involves a faster extraction process, more efficient and selective than in the case of liquid extraction with organic solvents. In supercritical fluids extraction “green solvents”, such as CO2, can be used and so the use of chlorinated solvents usually used in liquid extraction is avoided. In fact, CO2 is recognized by the Codex Alimentarius standards as suitable for use in organic foods. Supercritical fluid extraction enables us to obtain a completely natural extract containing the active ingredients, terpenoids and fatty acids while keeping all their medical activities and without containing residues of the extract.
Another widely employed method and useful in the production of plant extracts is that of extraction using organic solvents. With this method we can extract various plant substances, such as active ingredients, terpenoids and fatty acids, and also separate certain compounds depending on their solubility in different solvents. Currently the Spanish legislation on extraction solvents used in the food sector authorizes the use of butane, propane, ethanol, acetone, ethyl acetate, butyl acetate, carbon dioxide and nitrous oxide as solvents that can be used both in the extraction and in extractredissolution (RD. 2667/1998). Extraction with organic solvents allows whole plant extracts to be obtained, or desired fractions of food and phyto-pharmaceutical quality without excessive production costs.
The basic method to extract terpenoids and obtain essential oils is steam distillation. This special type of distillation is based on the balance of immiscible liquids. The boiling temperature of a mixture of two immiscible components is below the boiling point of either of them separately. When there are mixtures of liquids which are not miscible with each other, there is a kind of distillation that follows the law of Dalton on partial pressures. As a result of this behavior, and when one of the components is water, working at atmospheric pressure, a component can be separated at a higher boiling point than water at a temperature below 100°C. Because of this, with this technique it is possible to separate substances immiscible with water, such as terpenoids, which decompose at its boiling point or near it. It is often used to separate natural essential oils found in leaves, shells or the seeds of various plants. Depending on the technique used for the extraction of the terpenoids,the purity and yield of the essential oils will differ. Terpenoids from plants are widely used for their aromatic qualities and play an important role in traditional medicine, herbal remedies. They are currently the focus of study because of their potential antibacterial effect and other pharmaceutical uses.
Extraction of the fatty acids contained in the seeds can be undertaken by cold pressure, steam or solvent. We arestudying the utility and industrial performance of oils extracted by cold pressure of seeds in particular. A cold pressed oil is one which retains the same biological characteristics as found in the seeds. The temperature generated by the pressure is monitored and must not exceed 45°C in order to ensure the molecular stability of the polyunsaturated fatty acids, and to prevent the dissolution of waxes and other substances. Seed oil is an essential nutrient because it provides nutrients that the body can not synthetize itself, such as Omega 6 fatty acids (linoleic acid and arachidonic acid) and Omega 3 fatty acids (linolenic acid).The oil seeds of some plant species have important applications in the pharmaceutical, nutraceutical and dermocosmetic sectors.
To isolate and purify the different active ingredients contained in plant extracts, essentially we use two techniques: fractional distillation, which allows us to separate substances by their different boiling points, and chromatographic techniques, which enable separation by polarity inter alia.
Fractional distillation is a physical process used to separate mixtures (usually homogeneous) of liquids by heat, and with a large heat and mass exchange between vapors and liquids. It is used when it is necessary to separate compounds with similar boiling points. The use of a fractionating column allows greater contact between the rising vapors with the condensed liquid which goes down, by using different plates; this facilitates the exchange of heat between the vapors and liquids. This exchange causes liquids with a lower boiling point to become steam, and vapors of substances with higher boiling point to condensate, allowing the various compounds to distillate separately and subsequently the purified fractions to be obtained.
Chromatography is a physical method of separation of complex mixtures, which has a wide range of applications. It is a set of techniques based on the principle of selective retention, which aims to separate the different components of a mixture, enabling the amounts of these components to be identified and determined. Chromatographic techniques are very varied, but in all of them there is a mobile phase consisting of a fluid (gas, liquid or supercritical fluid) which drives the sample through a solid or liquid stationary phase fixed in a solid. The components of the mixture interact with a different form and affinity to the stationary phase, and they pass it at different speeds and in this way they can be separated and obtained in a pure form.