Influence of Harvest Time, Method of Preparation and Method of Distillation on the Qualitative Properties of Organically Grown and Wild Helichrysum italicum Immortelle Essential Oil

The most important process in immortelle is the extraction of the essential oil by distillation. The chemical properties of the plant depend largely on the cultivation type, climatic conditions and agrotechnical measures. In this work, studies were carried out on organically grown and wild immortelle harvested during the summer (July) and autumn (October) seasons of 2020. Immortelle samples were prepared by drying naturally in two ways: in direct sunlight and in shade. To extract the essential oil, immortelle was distilled in two ways: on an industrial and a laboratory scale. The essential oil was analyzed by gas chromatography to determine the composition and quality of the essential oil. The results of this work showed that the qualitative properties of the essential oil were influenced by the cultivation type, harvesting time, preparation method and distillation method. A higher yield (0.21% +/- 0.03) of essential oil was obtained from wild immortelle whereas a better utilization rate (0.38% +/- 0.09) of essential oil was obtained from the organically grown immortelle. It was also found that a higher yield of essential oil was obtained from the summer harvest (0.19% +/- 0.01) and a higher utilization rate from the autumn harvest (0.33% +/- 0.13) with the industrial scale distillation and shade drying. In general, better qualitative properties of immortelle essential oil were obtained from wild immortelle, which was confirmed by a chromatographic analysis and better content of gamma-curcumene (16.64% +/- 0.30) and neryl acetate (8.15% +/- 0.19) and other constituents except alpha-pinene where organically grown had a higher share (24.27% +/- 0.97).