Emerging science: rapeseed oil waste a green fuel source?

The Freising-based Fraunhofer Institute for Process Engineering and Packaging’s TeFuProt project aims to counteract the scarcity and long-term price increase of fossil fuels by using food waste for industrial applications.

The processing of rapeseed oil, widely used in food production, results in protein-rich by-products known as rapeseed meal and press-cake. “Up until now, this residue has been used mainly as a foodstuff in livestock farming but this usage is limited because of the bitter substances contained,” ​said Andreas Fetzer, scientist at the Fraunhofer Institute.

However, due to its ability to form foams, gels and films and retain water, rapeseed press cake’s proteins had the potential for a broad range of technical applications, according to Fetzer. They could, for example, be used to replace petroleum-based additives for paints, varnishes, adhesives, lubricants, building materials and polymers.

“The vegetable proteins are opening the door to the development of novel, sustainable, bio-based products with improved properties,”​ said Fetzer. This, he added, could reduce dependence on fossil resources and encourage climate-friendly production.

Research aims​

The challenge for the Fraunhofer Institute researchers was to develop processes to isolate proteins from the rapeseed meal and press-cake, and formulate them into dried powder or liquid solution for testing by development partners. Their functional properties, such as solubility, foaming and emulsifying were also analysed.

Fetzer and his colleagues successfully recovered four types of protein through four distinct processes.

“We de-oil, grind and dissolve the rapeseed press-cake in water​,” said Fetzer. “The mixture is then centrifuged to separate the solids from the liquids. After that, we refine the aqueous extract with the dissolved proteins.”​

The protein isolates recovered often have a protein content of more than 90%, the researchers noted.

According to Fetzer, the film-forming properties of the protein produced especially convincing results.

“Thus, proteins are principally suitable as alternative binding agents in paints and varnishes, wood stains or parquet coatings which usually contain petroleum-based raw materials,” ​he said. “Acrylates, for example, can be replaced by protein preparations.”​

Product applications​

The long-term project work of 18 partners of the research has produced a series of products, some of which are available as prototypes. These include biodegradable films and foams for packaging, flame-retardant insulating foams for construction, fibre protection and dye transfer inhibitors in eco-friendly laundry detergents. Other applications encompass thickening components for lubricants, binders for lubricating lacquers and additives in universal cleaning agents for wood surfaces.

“In many cases, we have successfully integrated the proteins into the products and generated properties with added value,”​ said Fetzer.

The next steps in the project are optimising the preparations and getting them ready for market.