Small fibers - big effect
Neutrons take a glimpse inside the molecular structure of plant-based foods
The evidence is in: excessive consumption of animal-derived products has many negative effects on our climate, our health and, crucially, on animal welfare. As a result, many consumers are adopting plant-based diets. The continuous development of novel plant-based foods such as yogurt, milk and meat alternatives is therefore thriving.
In order to optimise both taste and mouthfeel of these novel foods, a detailed understanding of their molecular structure is essential. Scattering techniques such as neutron and X-ray small-angle scattering are highly sought-after methods in the food industry since they allow for precise, quantitative insights into the molecular properties of plant-based foods.
Bridging industry and academia was the goal of the EU-funded innovaXN framework, which included many PhD projects carried out using scattering methods. Tong Guan’s thesis was one of them. “My project combined X-ray and neutron scattering experiments performed at various European research centres in order to elucidate how the structure of plant-based products changes depending on their ingredients”, explains Tong. Her project was the result of a collaboration between scientists from ETH Zurich, Paul Scherrer Institute, the industrial partner Planted Foods AG and the ILL. The team’s latest research was recently published in the journal Food Hydrocolloids.
Schematic illustration of the structure of PBMA from the nanoscale to the macroscale, with corresponding investigation methods.
Instrument D22 at the ILL.
“For this study, we focused on the impact of dietary pea fiber on meat alternatives”, says Peter Fischer, the principal investigator of the project. “It had already been shown that adding fiber improves the fibrous mouthfeel of these products, which many consumers highly appreciate - but the exact molecular mechanisms were not known. This is where our project came into play.”
The scientists observed that adding pea fiber led to the formation of micrometer-sized domains rich in cellulose, a long-chained sugar which is an important part of plant tissue. These domains then led to small cracks in the resulting product, ultimately resulting in a fibrous structure closely resembling meat. Interestingly, the addition of a mixture of pectin (another type of a plant-based sugar) and cellulose made the resulting products softer and less bite-resistant.
“In addition to scanning small-angle X-ray scattering, a high-resolution technique, neutron scattering experiments were key to this project”, explains Tong. The team exploited a particularly helpful property of neutrons known as contrast variation. “By using different mixtures of so-called heavy and light water (D2O and H2O), which interact differently with neutrons, we were able to selectively visualise proteins and dietary fiber. This is what allowed us to deduce the detailed information we were looking for”, says Lionel Porcar, responsible of ILL’s small-angle scattering instrument D22.
“Our findings can help improve the mouthfeel of and customer satisfaction with plant-based foods”, says Peter Fischer. This study highlights the importance of scattering methods and of industry-academia collaborations for the improvement of industrial products, specifically in the context of developing sustainable nutrition.
Reference: Guan, T., Lutz-Bueno, V., Schlangen, M., Diaz, A., Matsarskaia, O., Rühs, P.A. and Fischer, P., 2025. From nano to bite: Dietary fibers induce fracture mechanisms during high moisture extrusion of plant-based meat alternatives. Food Hydrocolloids, p.112241. https://doi.org/10.1016/j.foodhyd.2025.112241
ILL contact: Lionel Porcar, Sylvain Prévost
You can find a news article covering the first part of Tong’s work here.