Project Breeding4Protein: New protein sources from agricultural side streams

Traditionally, agriculture and the food industry breed crops for a single primary objective: to maximise the yield of a main component, such as sugar in sugar beet or oil in rapeseed. At the same time, processing generates large volumes of side streams that remain underused, such as sugar beet leaves and rapeseed cake (the residue after rapeseed pressing). This represents a missed opportunity, as these side streams contain valuable proteins with unique functional properties. 

The industry is keen to utilise these side streams, but so far the focus has mainly been on processing them retrospectively. This often results in inefficient processes, low yields and a weak business case. Breeding4Protein takes a fundamentally different approach: we investigate how to optimise the crop itself for improved processability and higher protein yields, without compromising the yield of the main product.

Breeding4Protein breaks down the traditional divide between plant breeding and process technology. In this project, we integrate both disciplines. We study and optimise the process, from understanding the cell structure and crop composition to protein extraction and application of proteins. The approach consists of three steps:

1. Selection of suitable crops and varieties
   At Breeding4Protein, we begin by screening existing crop varieties. We screen for both high main product yield and protein extractability from side streams. By analysing these traits together, we identify the most promising candidates.
2. Understanding the extraction process
   The second step involves unravelling the process of extracting proteins from the waste stream. We investigate which factors influence process efficiency and the yield. These could include, for example, a cell wall that is difficult to break down, an excess of organic acids, or the presence of other interfering substances. 
3. Feedback to the crop
   We then translate these process insights back into crop selection and breeding. By breeding and selecting varieties with fewer interfering components, the extraction process becomes significantly more efficient. This creates a new design principle: optimising both the process and its input to achieve a higher protein yield.

In the first phase of the project, researchers focused on protein extracting from sugar beet leaves, in particular the naturally occurring protein Rubisco. This protein has unique functional properties. Unlike many other plant proteins, it can form strong gel structures. This makes Rubisco highly suitable for applications such as meat alternatives, where texture and structure are crucial. 

Using the three-step approach, the team demonstrated that certain natural components in the leaves can interfere with protein extraction, thereby limiting yield. Through targeted breeding and selection of existing varieties they created a sugar beet with a leaf from which Rubisco can be extracted more effectively. The researchers carried this out on a pilot scale (up to approximately 100 kg of leaf), enabling the protein to be tested not only analytically but also in practical applications. 

Breeding4Protein contributes to a more efficient use of agricultural land. By utilising both the main crop and side streams, the total yield per hectare can be significantly increased. For industry, this means:

• Access to new functional proteins
• Greater diversity in protein sources
• Opportunities for more sustainable and efficient production processes

For society, the project supports the protein transition and food security by tapping into new resources without requiring additional agricultural land.

Breeding4Protein brought together partners across the entire value chain, from plant breeders to process technologists and food companies. This collaboration enabled direct translation of plant science insights into industrial processing and product applications. Initial partners included Coöperatie Koninklijke Cosun U.A., KWS SAAT SE, Quorn Foods and SESVanderHave. The project was funded by TKI Agri-Food (LWV20198).

Companies interested in developing new protein sources or improving existing processes are invited to collaborate with us in follow-up projects. Get in touch to explore the possibilities.