Vegetable oils play an important role in the pharmaceutical, cosmetic and food industries. Conventional methods of obtaining vegetable oils are extraction with organic solvents, such as hexane, and cold pressing. Recently, supercritical CO2 extraction has gain popularity for both the research and industrial purposes. In the master's thesis, we obtained oils from selected herbal drugs using the aforementioned methods. Afterwards, we analyzed fatty acid composition by the GC-MS method, determined the proportion of unsaponifiable matter and oil yields.
Hexane extraction was the most efficient method for pumpkin oil (26.89 %) and apricot oil (31.14 %), cold pressing for linseed oil (35.00 %) and CO2 extraction for poppy (36.50 %), linden (16.30 %) and calendula oil (13.70 %).
The proportions of unsaponifiable matter ranged from 0.60 to 4.37 %, with CO2 extraction yielding the most unsaponifiable substances of pumpkin seed oil, calendula oil and milk thistle oil, cold pressing was the most suitable for linden oil, while for flaxseed and apricot kernel oil, the methods were equivalent. When comparing fatty acid composition, different extraction methods did not significantly affect the fatty acid composition.
It can be concluded that CO2 extraction is a very good method for obtaining oils in terms of their fatty acid composition, proportion of unsaponifiable matter and yields, and will become an important part of vegetable oil production in the future. It is especially suitable for herbal drugs that contain less oil, as in these cases the yields were generally better. For herbal drugs that contained a lot of oil and are easily available, the conventioinal method of cold pressing was equivalent to CO2 extraction. From an environmental and health point of view, these two methods represent a rational alternative to hexane extraction.
It should be emphasized, however, that the definition of a particular extraction method for the production of vegetable oils as of the highest quality on the basis of evaluated parameters is not unambiguous. We must proceed from the ultimate purpose of the oil's use, i.e. as pharmaceutical, cosmetic or nutritional ingredient. The variety and proportion of unsaponifiable substances and the fatty acid composition have a significant effect on the properties of an oil as a raw material.
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