Rapid extraction of essential oils from freshly harvested plant material
A research project of the Technische Hochschule Ostwestfalen Lippe, Institute for Life Science Technologies.NRW, AG Verfahrenstechnik
Essential oils are formed by plants as secondary ingredients and are valuable raw materials for numerous products in the consumer goods industry. In Germany alone, 163,909 tons of essential oils were produced in 2011 - with a market value of 1.4 billion euros, which grew to over 2.0 billion euros by 2017.
Many essential oils are extracted in a steam distillation process lasting several hours, which is energy-intensive and therefore costly. In a previous project, however, a new method was developed that shortens the process to just a few minutes.
This project investigated the influence of various post-harvest treatments on the process and also tested the direct processing of freshly harvested plants without prior drying or freezing treatment.
Energy-efficientextraction of high-quality oils through rapid steam distillation
In labiates (Lamiaceae), the glandular scales in which the oil is stored are located directly on the leaf surface. If the leaves are briefly heated and then exposed to a vacuum, the scales burst open - presumably due to the increased vapor pressure of the oil - and release the oil.
In laboratory tests, it was possible to open a similar number of glandular scales in oregano and remove the oil - regardless of whether the herbs were processed fresh or dried or frozen after harvesting. These results speak in favor of using fresh herbs and avoiding time-consuming post-harvest treatment.
Building on this, the energy- and cost-efficient process was successfully implemented on a pilot scale. The essential oil was extracted directly from fresh oregano using rapid steam distillation and showed a similar composition to conventionally extracted oil. The main components of the oil were slightly enriched and a significantly increased antimicrobial effect was observed.
It can be assumed that the method is transferable to other Lamiaceae and Asteraceae. Further studies on various aspects are necessary and, in view of the very good prospects, also useful.
Ostwestfalen Lippe University of Applied Sciences, Institute for Life Science Technologies.NRW
Project management: Prof. Dr.-Ing. Ulrich Müller
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Final report"Rapid extraction of essential oils from freshly harvested plant material"