Method of gentle extraction and subsequent concentration at low temperature of natural compounds in the extract from plants

A unit performing a simple and effective way to extract active phytochemicals from the plant specimens has been developed. The unit is mobile enabling operation near the place of collection of plant specimens reducing waste of potential valuable phytochemicals. The design is based on counter current liquid extraction following a pretreatment, where the plant material is harvested and macerated to an extent increasing the extraction of relevant components. The pretreated plant material is fed to an inclined conveyor, counter currently with the extracting solution. The technology, known as solid/liquid extraction is developed on the basis similar to sugar extraction from sugar beets, albeit in a much more compact form. The equipment has been tested on extraction of ethereal oils from dried, stored oregano and extraction of natural compounds from freshly harvested Artemesia with 96% EtOH as the solvent. Preliminary results from a continuous oregano extraction show efficiency between 55% and 85% of a more ideal laboratory batch extraction of a marker compound like carvacrol, which is most abundant in the ethereal oil. The operation can be repeated with another liquid in order to extract compounds not soluble in the previous liquid and thus enabling optimal extractions of all compounds. Practically all known extracting liquids can be used by this equipment. Extracts from the extraction operation can subsequently be concentrated using a membrane distillation unit operating with hydrophobic microporous membranes for polar solvents and pervaporation membranes for unpolar solutes, where solutes with a low vapour pressure are retained, while components with higher vapour pressures permeate the membrane including water and most other solvents. The operation is performed at relatively low temperature enabling concentration of extracted solutes without deterioration due to influence of high temperatures.