Subcritical low-temperature extraction technology is a new method for extracting plant essential oils. It has the advantages of high yield, low consumption, good aroma, complete components, small investment, large scale, simple operation, and the flower residue after extracting essential oils (extracts) still has great utilization value. It has been widely used in the extraction of rose essential oil, jasmine essential oil and other plant essential oils. Extraction method, subcritical low-temperature extraction method, etc. all get extracts, which contain plant waxes, etc., and can only be used in oily flavors, which limits its scope of use. If the extract is dissolved with ethanol, and then the wax is removed by freezing, crystallizing the wax, and filtering at low temperature, the pure oil obtained after concentrating and recovering ethanol at room temperature is liquid, which can be completely dissolved in perfume.
Jasmine is a general term for evergreen shrubs or vines of the genus Jasminum in the family Oleaceae. It is native to India and Pakistan. It was introduced to China during the Han Dynasty and widely planted. Its leaves are green, the flowers are white, and the fragrance is strong. Jasmine essential oil is a secondary metabolite released during the opening process of jasmine flowers. It is widely used in scented tea production, cosmetics, food and pharmaceutical industries for its elegant smell and multifunctional bioactive substances. The main components are benzyl alcohol or its lipids, jasmine, linalool, linalool benzoate, etc. It also contains substances such as oxaline and jasmine lactone. At present, the main extraction methods of jasmine essential oil are distillation extraction, adsorption, leaching, carbon dioxide supercritical extraction and subcritical low-temperature extraction.
The distillation extraction method is to extract the water vapor fraction of the sample with a solvent for liquid-liquid extraction to obtain essential oil, and the extraction rate of trace components is relatively high. The disadvantages are high operating temperature, long time, and distortion of the aroma of the obtained essential oil, so it is less used. Carbon dioxide supercritical extraction is a low-temperature extraction separation technology, but the process requires high pressure, high equipment manufacturing requirements, large equipment investment, and high product cost, which restricts the application of this technology in essential oil extraction. The adsorption method mainly uses activated carbon to absorb the aroma released by jasmine, and then uses carbon dioxide supercritical equipment to extract and adsorb saturated activated carbon to obtain jasmine essential oil. This method mainly targets the top fragrance, so the yield is low. In order to increase the yield, leaching extraction is also required. The leaching method mainly uses hexane to extract jasmine, and the extract yield is 0.22%~0.28%, of which the net oil content is more than 60%. It is currently a widely used method, but the disadvantages of this method are obvious. In order to retain the aroma of the essential oil, a large amount of solvent is required. In order to remove the solvent from the extracted extract, ethanol needs to be further added for secondary separation, which is complicated. Hexane and ethanol are extracted twice, and the solvent is removed twice by heating, resulting in volatile loss of essential oil and heating taste change.