Extracting the essence of natural materials without a change!
Extraction is an ancient technique of removing certain compounds from a raw material, usually of natural origin. Most commonly extraction is performed with a solvent which later has to be removed again in order to get a pure extract. Additionally, due to the temperature this process is performed at it runs the risk of kickstarting unwanted microbiological processes, such as bacterial activity. An alternative to this, which we perform at FeyeCon, is the extraction with CO2. Extraction is the most common application of supercritical fluid technology.
CO2 extraction is similar to making filter coffee, in fact the first use of this process was by K. Zosel for the decaffeination of coffee. The supercritical fluid is guided over a packed bed and will carry the soluble fraction of the material we want to extract. Afterwards the carbon dioxide is simply removed trough depressurization. It leaves no traces in residue or extract and is regarded as a food safe solvent. The extraction can also be performed at mild temperatures preserving the products natural consistency. It is non-toxic and non-flammable which reduces safety costs.
The thermodynamic parameters are the solubility of the extracted compounds in combination with solvent density and temperature. When the solubility is plotted against density at given temperature, the solubility curves will have an exponential shape. The thermodynamics of the combined compounds in the raw material will be responsible for the purity of the extract.
The solubility is not only affected by the concentration of compounds in the raw material but also the manner in which it is attached to this raw material. This will influence the extraction time. As an example: The algae nannochloropsis are difficult to extract, not because of the solubility of the oils, but because of the impermeable membrane of the algae.
The engineering will try to minimize pressure, process volume, flow and time in order to reduce the OPEX and the CAPEX. At the same time, it is essential to offset these parameters against the yield and quality of the product. The combination of the product quality, yield and costs will establish if we have an economically viable process.
Supercritical CO2 extraction can be used for a number of different materials and purposes, for example the extraction of fragrances, herbs, active compounds, flavours, essential oils or edible oils.