From nano to bite: Dietary fibers induce fracture mechanisms during high moisture extrusion of plant-based meat alternatives

High moisture extrusion (HME) is a key technology to produce meat alternatives with a fibrous texture. The incorporation of dietary fibers in plant-based formulations used for extrusion has shown to enhance the fibrous texture, yet the underlying mechanisms in the extrusion process remain elusive. Here we unravel the dietary fibers induced structuring mechanisms in extrusion from the nanoscale to the macroscale by combining small-angle neutron scattering, scanning small- and wide-angle X-ray scattering-based imaging, and automated image analysis (Fiberlyzer). The incorporation of pea fiber does not change the nanostructure but leads to the formation of cellulose-rich regions at the microscale, which acts as nucleation sites to initiate fractures in extrudates, resulting in a greater prevalence of fibrous structures at the macroscale. The incorporation of a mixture with high pectin-to-cellulose ratio alters nanostructures and reduces mechanical strength, while nanostructures and the mechanical strength can be preserved when incorporating a mixture with low pectin-to-cellulose ratio. Our study examines the dietary fibers induced structuring mechanisms in extrusion across multiple length scales, providing valuable insights for optimizing formulations in plant-based alternatives.