In his doctoral dissertation, Markus Nikinmaa (M.Sc. Tech.), research scientist at VTT, investigated how to improve the structure of high-fibre snack products. His findings demonstrate that the choice of wholegrain flour and the application of bran bioprocessing techniques can significantly enhance product texture. This enables the development of fibre-rich snacks that remain appealing to consumers.
Adequate dietary fibre intake is linked to numerous health benefits, including a reduced risk of cardiovascular disease, type 2 diabetes and obesity. Despite this, most people fall short of recommended fibre intake levels.
Popular savoury snacks, such as puffed chips or crisps, are typically made from low-fibre ingredients like corn or potato flour. Incorporating wholegrain flours or cereal brans could substantially enhance their nutritional profile. However, high fibre content often degrades texture and mouthfeel, resulting in denser, harder and less enjoyable products.
In his research, Markus Nikinmaa focused on improving the structural quality of fibre-rich snacks made using extrusion technology.
“Extrusion is widely used in the food industry to produce items like cheese puffs, breakfast cereals, spiral-shaped chips and infant snacks. In the process, the material is forced through rotating screws in an extruder, which results in puffed, airy products,” Nikinmaa explains.
Oat flours rich in fat, fibre and protein yield denser snacks
Nikinmaa’s research had two main components. In the first, he analysed 30 different wholegrain oat flours, which varied in composition based on oat variety, growing conditions and harvest year.
“Our results showed that fat content had a particularly strong impact on the final product's texture. Higher fat levels reduced expansion during extrusion, producing denser and less airy snacks,” he says.
High levels of fibre and protein also resulted in harder textures. In contrast, flours with higher starch content produced lighter, puffier snacks.
Bioprocessing boosts rye bran potential
In the second part of the research, Nikinmaa explored how to increase the use of rye bran in extruded snacks. Bran is an exceptionally fibre-rich ingredient but tends to disrupt the porous structure of extrudates, resulting in dense products.
The research findings showed that both product structure and texture were significantly improved by bioprocessing, which involved the use of fibre-degrading enzymes and lactic acid fermentation. The results are also applicable to other brans, such as wheat bran.
“The end result was just as airy as snacks made from refined white rye flour, but with substantially higher fibre content,” Nikinmaa explains.
The study was conducted as part of a project for General Mills Inc., resulting in a patent based on the findings.
Practical applications and commercial potential
Product appeal is key to driving healthier dietary choices at the population level. Nikinmaa’s research offers new solutions for developing healthier, high-fibre snack products without compromising texture or taste.
“The food industry can apply these results right away. Selecting appropriate oat varieties and optimising flour composition is already possible with existing technology. Bioprocessing does require an additional pre-treatment step, but it does not significantly alter the production technology,” Nikinmaa says.
The research also led to an unexpected discovery that sparked the creation of a new spin-off company. During the extrusion experiments, certain extrusion conditions yielded material with protein concentrations higher than 70%. This finding is now being utilised by Happy Plant Protein, a company focused on developing plant-based proteins.
Dissertation: Wholegrain and dietary fibre in extrusion
Place of public defence: 4 July 2025, at 11–13 am (Finnish time), Forest Sciences Building (Metsätieteiden talo)
