There are two ways to distill roses. One is water steaming, that is, putting roses in a distiller, injecting water, and then heating and distilling. The other is to put roses in a distiller and distill them by injecting steam. Steam distillation also evolved into two types. Traditionally, steam is injected from the bottom of the still. Now there is a new way, which is to spray downward from the top of the still, like a shower.

The rose essential oil obtained by traditional distillation is only the volatile and insoluble part of rose, not the whole taste of rose itself.

The principle of solvent extraction is to extract roses with solvent. These flowers are packed in a special extractor and then extracted at room temperature. The solvents used are refined, usually petroleum ether. The solvents penetrate into flowers to dissolve natural flower oil, some plant waxes, protein and pigments. The solution thus extracted is pumped into an evaporator and concentrated at a low temperature, and then all solvents are removed by vacuum concentration to obtain concentrated natural plant extracts. These are only preliminary extracts. In order to obtain rose pure oil (technically called pure oil), it is necessary to dissolve the extract in pure alcohol to remove substances insoluble in alcohol such as plant wax, and then heat the filtered alcohol solution to volatilize the alcohol, so as to obtain pure oil or crude oil without plant wax and other components.

The rose essence obtained by solvent extraction basically has the fragrance of rose itself. However, because the chemical components of the solvent used in extraction can not be completely removed, it will cause some people to be allergic when used on the skin.

Supercritical extraction is one of the new methods this year. The principle of supercritical CO2 fluid extraction (SFE) separation process is based on the relationship between the solubility of supercritical fluid and its density, that is, the influence of pressure and temperature on the solubility of supercritical fluid. In the supercritical state, the supercritical fluid is contacted with the rose, and the components of polarity, boiling point and molecular weight are sequentially extracted. Then, the supercritical fluid is transformed into ordinary gas by means of decompression and temperature rise, so that the extracted substance is completely or basically precipitated, thus achieving the purpose of separation and purification. Therefore, the extraction process of supercritical CO2 fluid is a combination of extraction and separation.

The characteristics of supercritical fluid extraction of rose essential oil are as follows

1. Supercritical extraction is carried out under the cover of gas near room temperature (35 ~ 40℃) and carbon dioxide (CO2), which effectively prevents the oxidation and escape of heat-sensitive substances in roses. Therefore, the effective components of rose are retained in the extract, and substances with high boiling point, low volatility and easy pyrolysis are extracted at a temperature far below its boiling point.

2.SFE is the cleanest extraction method. Because no organic solvent is used in the whole process, there is no residual solvent in the extract, which ensures the natural nature of 100% rose.

3. Supercritical method can be used for partial extraction in advance or complete extraction. The rose essential oil extracted by some extraction methods is liquid, while the rose essential oil extracted by all extraction methods is solid at room temperature (because it contains non-volatile components in roses, or wax grease). When in use, the bottle filled with supercritical rose essential oil needs to be put into hot water of about 50 degrees, and the essential oil can be blended before use.

Advanced rose essential oil by supercritical method can reproduce the true fragrance of roses. At the same time, the composition of roses is also the most complete. However, the biggest concern of this method is whether roses and flowers are organic. The disadvantage of supercritical extraction is that all plant components, including fertilizer and pesticide residues, are presented.