TexProSoy

Why this project?

The conscious consumer is adapting their consumption behaviour to create impact in areas such as sustainability, health, taste, authenticity and animal welfare. This consumer increasingly demands alternative plant-based proteins on the menu that also contribute to a balanced diet.

With the growing interest in and use of plant-based proteins by the food industry, the lack of knowledge about the behaviour of these proteins during different processing steps is gradually becoming a bottleneck for further exploitation. For this reason, the project aimed to expand fundamental knowledge through an in-depth study of the behaviour of plant proteins during various processing steps (extraction, drying and extrusion).

High-moisture extrusion (HME) of plant proteins is used to produce a wide range of food products, including meat alternatives, as it creates a fibrous structure comparable to that of meat.

The extrusion process consists of three essential steps:

• In the first step, the plant protein powder is mixed with water in a twin-screw extruder to form a homogeneous mass.
• In the second step, this mixture passes through a cooking zone of the extruder where heat and pressure are built up.
• In the final stage, the heated product is pressed through a die equipped with a cooling element.

It is assumed that mechanical and thermal shear stresses play a key role in the formation of these structures. Protein denaturation during the process causes changes in protein structure and enables alignment of the proteins in the direction of flow. However, the exact mechanism behind this is not yet fully understood.

Within TexProSoy, the entire processing chain from soybean to finished product was studied, with a focus on the properties of soy proteins throughout the process. Flemish soybeans with well-documented cultivation conditions were used. This work built further on ILVO’s expertise in the cultivation of soy varieties in our region (Soy2Grow).

Research approach & results

The TexProSoy project was a collective, fundamental research project (cSBO) aimed at building knowledge on the mechanism behind the formation of fibrous structures during high-moisture extrusion. Specifically, the following aspects were investigated:

• Characterisation of different soy varieties to map the composition and properties of the raw materials.
• A study of the influence of extraction process parameters on the proteins of these soybeans, including characterisation of the resulting protein extract and side streams.
• Investigation of the impact of the HME process on the macro- and microscopic properties of soy proteins to gain insight into structure formation during extrusion.
• Study of the impact of modifications to the starting material for the HME process, such as the addition of various reagents and non-protein soy constituents, to identify their role in structure formation.
• Assessment of nutritional properties (anti-nutritional components) and evaluation of volatile aroma compounds of the extruded product.

Access to the project results

The project concluded in October 2024. The project results from KU Leuven and ILVO have been published in several scientific publications. More information on the results can be found in the article: The Impact of Processing on the Structure of Protein Extrudates: Results from the TexProSoy Project.

Target Group

The project results are primarily aimed at ingredient suppliers that include plant-based proteins in their portfolio or are interested in adding them to their portfolio. Another key target group is the processing industry that uses plant proteins. The meat, bakery, dairy and ready-meal sectors, among others, are facing challenges related to the protein transition.

In addition, knowledge about different soy varieties can support Flemish farmers and horticulturalists in crop selection. Increased interest from the food industry in Flemish soy and other protein-rich crops will help secure a market outlet for these producers.

Follow-up actions

During the project, it became clear that sufficient attention must be paid to both the impact of cultivation parameters and the impact of processing parameters on the final quality of protein-rich ingredients. In the CUPRIFAB project (cSBO), this integrated approach will be applied to faba beans. Insights and analytical techniques developed within TexProSoy will be further utilised

Project partners

Flanders’ FOOD managed and coordinated this research project. The scientific work was carried out by:

• The Laboratory of Food Chemistry and Biochemistry at KU Leuven (Prof. Arno Wouters, Prof. Jan Delcour and Dr Kristof Brijs)
• The Technology and Food Science unit of the Flanders Research Institute for Agricultural, Fisheries and Food (ILVO) (Dr Bart Van Droogenbroeck and Dr Geert Van Royen)