Researchers look at old baked goods as basis for bioplastics

In Germany, University of Hohenheim and the Fraunhofer WKI researchers succeeded in extracting the basic chemical hydroxymethylfurfural (HMF) from old baked goods that can no longer be marketed as food as a way to use HMF as a starting material for biobased plastics.

With HMF, a starting material is available that can, for example, replace formaldehyde in bio-based adhesives. The Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI, and the University of Hohenheim in Stuttgart were able to prepare HMF for further processing on a semi-industrial scale.

In Germany, over 500,000 tons of old baked goods are produced every year that are not easily suitable for further consumption or as animal feed. So far, their use has been mainly energetic, for example in combustion processes or in biogas plants. Old baked goods such as bread, rolls or cakes contain large amounts of starch. The starch can be converted into the basic chemical HMF, which offers potential for a variety of applications.

The project team at the University of Hohenheim developed a process for the so-called hydrothermal treatment of stale baked goods, through which moist biomass is converted under heat and slightly increased pressure. From the old baked goods and the starch contained in large quantities, HMF is produced in an aqueous solution and coal. “We have chosen the process parameters such as pH value, temperature and duration in such a way that the highest possible yields of HMF can be achieved,” explains Markus Götz, a member of Prof. Dr. Andrea Kruse at the University of Hohenheim, who heads the project. Coal is produced as a by-product of the hydrothermal treatment. It can be used as a biofuel or as a soil fertilizer.