The lectorate Biobased Building Blocks and Products (BBBP) is one of the lectorates of MNext. These lectorates support companies in their ambitions to reuse agricultural waste streams and refine their valuable compounds. 25% of the production of onions in the EU takes place in The Netherlands. The cleaning, sorting and packaging of these 1.5 million tons of onions, leaves a waste stream of onion peels, stems and low quality onions of 20.000 tons on a yearly basis. This waste stream is fermented into biogas and high valued compounds are lost during that process.

One of the most value compounds in onions is the essential oil. This is used as a food flavor. Commonly steam distillation is used to isolate the oil from the onions. However, the high temperature destroys other compounds like proteins. To prevent these losses, the essential oil will be refined from the onion waste stream through a solid-liquid extraction.

Goal of internship
“Design an extraction process for essential oil from onion waste”
The Project involves:
1) Determine the main compounds in onion oil through literature.
2) Test the possibilities of liquid-solid separation on oil and protein yield
3) Find a “green” solvent for the extraction
4) Measure the equilibrium concentrations during the extraction.
5) Design an extraction process and predict the use of solvent and the yield of the essential oil.

Starting date
February 2024. The length of the assignment is 5 months.
The intern will be part of a research team supervised by Wim Gaakeer.

Desirable skills/qualities of the student

The student should be able to carry out research in scientific literature, experimental work at a chemical lab (filtration, extraction, HPLC-analyses), modelling (Excel and/or Matlab) and unit operation design. The preferred background is chemical engineering, however, chemistry or biochemistry are also possible.

Contact person concerning this assignment : Wim Gaakeer
Phone : +316 104 29 181
E-mail :

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