A recent patent gives an account of a new method for extracting natural products by using a microwave source of radiation. Based on a relatively simple principle, this method involves immersing vegetable material in a transparent solvent with microwave radiation. The internal heating of water within the vegetable material distends it and makes the glands and oleiferous receptacles burst. This process thus frees organic liquids which disperse and dissolve in the solvent used.
It is certainly most propitious to investigate the potential of such a technique and to compare it with more classic methods, such as hydrodiffusion, due to the present technical and commercial situation, which calls for research into new extracts and new extraction techniques.
We have used these two methods to treat different cultivated plants: five Umbelliferae, one Compositae and seven Labiatae. There is a double purpose for this approach. First, we want to determine the advantages and disadvantages of this technique in terms of research. Secondly, we intend to make appropriate comparisons between microwave extracts and essential oils coming from the aerial part of these plants.