OPTICAL PROPERTIES OF OIL EXTRACTS AND RESIDUES OF MEDICINAL AND AROMATIC HERBS

Abstract

The purpose of this work is to conduct a comparative study of attenuated total reflection infrared spectroscopy, diffuse-reflection electron spectroscopy and refractometry of the optical characteristics of a series of oil extracts, residues and dry-milled (<0,5 mm) aromatic and medicinal plant materials of different origin and anatomical localisation (roots, grass, flowers). Sunflower oil infusion was carried out in a water bath (90 °C) for one hour, followed by storage at room temperature for six months. For the studied series of extracts, the refractometry method allowed the linear dependency of the refractive index and iodine value to be obtained. This indicates that the extraction ability of the oil is determined not only by the fatty acid composition of the triglycerides of the samples, but also by the selectivity of the lipophilic components present in the extractant itself. The obtained data are consistent with the change in the intensity of the characteristic bands (320 nm) in the electronic spectra of extracts, residues and dry raw materials. The individual lipophilicity of oil extracts is confirmed by their IR spectra in the absorption region of C = C-bonds (1653 cm^-1), valency (3008 cm^-1) and deformation (722 cm^-1) vibrations of the CH-groups with a double bond (CH = CH) when compared with the spectra of residues and dry raw materials.