CHARACTERISATION OF STEAM-EXTRACTION PROGRESS OF SOME MEDICINAL PLANTS BASED ON THE EVOLUTION OF PHYSICAL-CHEMICAL PARAMETERS OF THEIR HYDROLATES

Seven medicinal plants of the Albanian flora (Juniperus communis L., Juniperus oxicedrus L., Laurus nobilis L., Rosmarinus officinalis L., Salvia officinalis L., Satureja montana L., Thymus vulgaris L.) were steam-extracted by a self-made laboratory-scale apparatus for 140 min, and monitored each 10 min. The extraction progress was characterized by systematic density, surface tension, refraction index, and dry residue measurements. A continuous decrease of densities and refraction index were observed for the hydrolates of Juniperus communis L., Satureja montana L., and Juniperus oxycedrus L. Significant relative density changes of 89.8, 81.0 and 86.8%, respectively, were observed for them within the 1st hour of extraction. The refraction indices found for all the hydrolates ranged from 1.341-1.361. Linear relations between the hydrolate densities and their refractive indices were found for Juniperus communis L., Juniperus oxycedrus L., Satureja montana L. and Thymus vulgaris L. Both juniper species showed high initial surface tension values of 61.4 and 60.7 mN m(-1), respectively. Meanwhile at the first stages of extraction, the hydrolates of Satureja montana L. and Salvia officinalis L. revealed an abrupt increase of the surface tension, followed by a steady increase. The highest dry residues were obtained from the hydrolates of both juniper species and Satureja montana L. After 1-h extraction, these plants revealed considerable decreases in the dry residues of their hydrolates: 93.5, 89.2 and 93.3%, respectively. The lowest change in dry residue was recorded for the hydrolate of Rosmarinus officinalis L.