Rosehip oil is obtained from the fruit of the rose hip. This is derived from the dog rose or also Rosa canina L., Rosa rugosa Thunb., Rosa pendulina L. The plant belongs to the Rosaceae family and grows mainly in the wild. It prefers moderately dry to fresh soil. With a height of 2-4 meters it forms long arching overhanging branches with sickle-shaped spines.
The rose hip bush originates in East Asia or Europe. It is native to mild climates like Europe, Africa, Asia and America. Some literature traces its origin back to the country of Chile, where it was intensively cultivated.
The flowering period starts in spring and lasts only a few days. From fertilization to harvest, ovoid red fruits, the rosehip, develops. These are hairy on the inside and bear the actual fruits: small light-coloured nuts. If the fruits are not harvested, they remain on the shrub until the next spring.
The seeds are separated from the pulp and then pressed.
Another way with higher yield is extraction with solvents. A distinction is made between two methods: The conventional and the modern extraction. In both methods the seeds must first be opened. The conventional extraction uses organic solvents to extract the oil from the seeds. Then the solvent is evaporated and releases the oil.
In modern extraction, the seeds are opened mechanically, using ultrasound or microwaves and then extracted with a so-called supercritical gas. Strictly speaking, this is also a solvent, which is liquid at a very low temperature. Supercritical carbon dioxide or propane are liquid at low temperatures below freezing point and can be used as an extraction agent at high pressures. If the temperature is gradually increased, these substances change their aggregate state and evaporate. When all the solvent has evaporated, only the extracted oil remains.
With both the modern and the conventional method, subsequent purification and refining steps must be connected in order to obtain a pure oil. In order to prevent fast decay, tocopherol, also called vitamin E, is often added.
Rosehip oil is a clear liquid with a light yellow to orange-red colour. The odor is nutty, greasy, sweet-sour or metallic. Depending on the method of production, the oil may be tasteless or have a characteristic flavour.
The main components are linoleic, oleic, alpha linolenic acid, tocopherols and carotenoids.
Rosehip oil is used for the treatment of dry and cracked skin. A further active ingredient, transretinoic acid, helps to support the formation of new collagen and skin renewal. Due to the fatty acids, the moisture remains in the skin and thus has an additional positive effect. The oil is also used in the treatment of eczema, psoriasis, scars and burns, in order to achieve relief or rapid healing. It not only supports normal skin formation, but also prevents pathological thickening of the upper skin layers.
The oil is therefore also used in the cosmetics industry as an accelerator for skin regeneration and collagen build-up.
The production method is also reflected in the fatty acid profile of the oil. Producing the il with the modern method results into a significant increase in linoleic and linolenic acids. The active ingredient class of carotenoids was also extracted to a greater extent using the supercritical method. These substances play an important role for the nutrition or cosmetics industry.
If an oil with enzymatic effect is desired, it should only be extracted by pure pressing as this does not destroy the enzymes.
If the oil shows a high value of beta-sitosterol (>4000mg/kg), it is probably from Poland. The content of different stigmasterols may further indicate the origin and thus possible blending.
If an oil with a high carotenoid content is desired, an oil produced by the classical extraction method should be chosen. It has been shown that an increased proportion of these could be obtained by using organic solvents.
To save costs, the oil is often blended with soybean, sunflower or corn oil. A corresponding analysis should be done at least with infrared spectroscopy.
When stored in a cool and dark place, rosehip seed oil has a shelf life up to 11 months.