Bioactive minor components from vegetable oils

Renewable resources used in the production of biofuel are increasingly gaining importance. The vegetable oils involved, for example from rape seed or soy, contain various minor components (valuable materials and contaminants). On the one hand, biodiesel contains contaminants which can negatively affect the quality of the fuel. On the other hand, smaller amounts of important valuable materials such as bioactive Vitamin E (α-tocopherol) can also be found. To date, when biodiesel is burned, these valuable materials are normally burned along with it.

Due to its antioxidant properties tocopherol plays an important role in the human body, where it protects cells from the damaging effects of oxygen. Natural tocopherol-containing extracts are separated from the seeds of oil-containing plants, especially from wheat, corn, soy, cotton and rice, and then enriched. On an industrial scale, synthetic vitamin E is produced as a racemic mixture. Since synthetic tocopherol is relatively unstable, it is normally bound to an acetyl group. Through this process it loses all antioxidant properties. Up to 50 percent of the absorbed synthetic tocopherol can, however, be converted to natural vitamin E by the body.

The goal of this project was to develop an adsorptive process at pilot plant scale in which valuable bioactive minor components could be extracted as additional, value-added products in plant processing. To this purpose, we included polymeric nanoscale adsorber particles in a new process concept for the separation of substances.

For the separation of bioactive α-tocopherol from vegetable oils nanoscopic-sized polymeric particles with free binding sites on the particle surfaces were developed. In the patented NANOCYTES^® process from the Fraunhofer IGB we mixed suitable monomers with so-called cross-linkers. By using the miniemulsion polymerization process we obtained nanoscopic-sized polymeric adsorber particles ranging from 200 to 300 nanometers in one step [1, 2]. Through the addition of suitable imprinting molecules and the subsequent extraction of these molecules, chemical negative imprints on the particle surfaces are created (Fig. 1).

The polymeric adsorber particles were then attached to polymeric packing materials and fixed into place. The coated packing materials were integrated into a technical process and a demonstration plant (Fig. 2) was developed at the Fraunhofer IGB.

In this project we were successful in producing polymeric adsorber particles for the separation of α-tocopherol from vegetable oils. To this purpose we optimized the polymer composition of the adsorber particles to achieve the maximum adsorption of α-tocopherol [3]. Up to 24 µg of tocopherol adsorb onto 1 mg of specific particle material.

In order to enlarge the adsorption surface, the polymeric adsorber particles were then attached to polymeric packing materials as carrier structures and integrated into an adsorption column. For the optimal adsorption of tocopherol onto the polymeric particles, their concentration in the column should be in the area of up to 30 µg/ml. By contrast, untreated packing materials displayed only very limited adsorption capacities. By changing the solvent, the tocopherol can be completely separated from the adsorber column via extraction. The columns are then again available for further cycles.

Consequently, a demonstration plant is now available for research and development projects focusing on the separation of various minor components from vegetable oils, plant-extracts and biodiesel. After reconditioning the oilseeds, the plant can be utilized directly on site at the oil mill, in the plant-processing industry or by biofuel producers.

By adapting the polymeric adsorber material, the demonstration plant developed here for the separation of valuable materials and contaminants from vegetable oils can be applied to other separation tasks for bio-based oils and plant-extracts. In order to increase the adsorption surface, packing materials with low packing densities and thus low free volumes can also be used in the future.

[1]   Tovar, G. E. M.; Kräuter, I.; Gruber, C. (2003) Topics in current chemistry 227, 125-144

[2]   Vaihinger, D. et al. (2002) Macromolecular Chemistry and Physics 203, 1965-1973

[3]   Neumann, M. (2009) Entwicklung von molekular geprägten Polymernanopartikel zur Gewinnung von bioaktiven Minorkomponenten am Beispiel von alpha-Tocopherol, Fachhochschule Recklingshausen

We would like to thank the Fraunhofer-Gesellschaft for funding the project “Obtaining bioactive minor components from plants” within the scope of its program for small and medium-sized enterprises (MEF).