Rheological and Structural Basis for the Texture-Structure Relationship in Nigerian Cassava-Based Swallow Foods: A Fundamental Investigation

Swallow foods produced from cassava, including fufu, amala, and pounded yam analogues, are the most widely consumed starchy food forms in southern Nigeria, yet the molecular and structural basis for their characteristic textural properties, specifically viscoelasticity, cohesiveness, and mouth-feel, has not been systematically investigated. This fundamental study investigates the structure-texture relationship in cassava-based swallow foods using a multi-scale characterisation approach. The theoretical contribution is a constitutive rheological model for cassava-based swallow food gels that links molecular-scale network parameters including polymer chain entanglement density, cross-link concentration, and starch crystallinity to macroscale rheological properties including storage modulus, loss modulus, yield stress, and creep compliance. The model is developed from first-principles using polymer network theory and validated by a comprehensive experimental programme. Samples were prepared from TMEB419 and white fermented cassava flour from Delta and Enugu States, using traditional and modified processing conditions. Multi-scale structural characterisation includes small-angle X-ray scattering for nanoscale polymer network structure, atomic force microscopy for surface and microgel structure, and confocal laser scanning microscopy for network visualisation. Rheological measurements encompass small amplitude oscillatory shear, large amplitude oscillatory shear, creep recovery, and tribology measurements simulating oral processing. The constitutive model predicted experimental storage modulus and yield stress values with errors below 12 percent. Oral processing was modelled using tribological parameters. The study contributes a rigorous fundamental understanding of cassava swallow food texture, enabling rational product design. Keywords: rheology, cassava swallow, texture, constitutive model, food structure