Value-added material utilization of press residues from protein extraction from green biomass (Presswert)

Permanent grassland is important for soil and water protection and, as a carbon sink, makes an important contribution to climate protection. In the field of grassland use, a project at the German Institute for Food Technology (DIL) is investigating fundamental scientific questions for a process for extracting techno-functional proteins from grassland plants. In addition to the protein-rich pressed juice, a relatively dry press residue is produced, for which it is necessary to find ways of utilization that add as much value as possible.

This is where the Presswert project comes in. It complements the DIL project by using the press residues produced there in a high-quality material application for the extraction of fibers for paper production and hydrogels. The project is being carried out in close cooperation between the two Thünen Institutes for Agricultural Technology and Wood Research. In addition to the DIL, GeCo GbR and the Klingele paper factory are also involved as associated partners.

Research at the Thünen Institute of Agricultural Technology focuses on extracting the hemicellulose fraction from press residues, which are to be converted into hydrogels through appropriate chemical modifications. Hydrogels are playing an increasingly important role in modern agriculture and forestry. They can store large amounts of water and release it slowly to plants, thereby ensuring water supply and thus crop yields during prolonged dry periods, such as those expected in light of climate change. Unlike synthetic materials, which are widely used today, hemicellulose offers the advantage of being bio-based and biodegradable, thereby creating an environmentally friendly and sustainable solution.

At the Thünen Institute of Wood Research, however, the focus is on the cellulose-rich fiber fraction. The goal is to extract this fraction using the simplest possible technologies while simultaneously achieving high pulp yields and good paper strength. This enables paper mills to extract fresh fibers directly on-site with minimal investment, thereby countering the declining quality of waste paper that has been observed in recent years due to rising recycling rates. The use of fresh fibers from annual plants such as grass expands the raw material base for paper mills and is particularly promising and sustainable.

Both Thünen Institutes work with the same press residues and are initially optimizing their respective processes for extracting hemicellulose and the cellulose-rich fiber fraction. However, the greatest value creation from the use of grassland biomass is achieved only through an optimal combination of the individual utilization pathways. Therefore, the overall goal of Presswert is to coordinate the developed processes in such a way that all recovered fractions can be utilized as much as possible in material form. This additional value creation from the press residues through hydrogels and paper fibers will also increase the economic viability of protein extraction from green biomass as an innovative food source for future nutrition.  

Project lead:

Prof. Dr. Ulf Prüße (Thünen-Institut of Agricultural Technology)

ulf.pruesse@thuenen.de