A structure - function related changes in rheological properties of pigmented corn after low temperature extrusion

The structure-function relationships of pigmented corn flours under mild processing conditions remain poorly characterized, limiting their application in functional food systems. This study evaluated the impact of mild extrusion (50 °C, 30 % moisture) on four pigmented corn varieties (yellow, orange, red, purple) through comprehensive analysis of particle morphology, hydration properties, and rheological behavior. Extrusion induced variety-specific modifications: yellow corn exhibited increased elastic modulus (G′: 426 → 720 Pa, +69 %) and enhanced water absorption capacity (3.10 g/100 g), while purple and red varieties retained superior native gel hardness (2.95–3.89 N) but showed reduced post-extrusion elasticity (G′ decreased 22–38 %). Thermal stability varied significantly, with purple corn demonstrating minimal breakdown viscosity (8.0 ± 0.0 mPa·s) compared to orange corn (434.0 ± 15.6 mPa·s). Particle size distribution analysis revealed variety-dependent resistance to mechanical breakdown, with red and orange extrudates maintaining structural integrity. Principal Component Analysis identified processing method (29 % variance) and pigmentation (17.1 % variance) as primary differentiating factors, linking anthocyanin content to enhanced texture properties and carotenoid-rich varieties to improved viscoelastic balance. These findings demonstrate that mild extrusion enables targeted modification of functional properties in pigmented corn. Native purple and red flours are suitable for applications requiring firm gel structures, while extruded yellow corn provides enhanced water interaction properties for texture-modified products. The phenotype-specific responses to processing provide a foundation for strategic ingredient selection in functional food formulations. • Mild extrusion variously altered technofunctional properties across four pigmented corn varieties. • Yellow corn showed enhanced structural properties while anthocyanin-rich varieties exhibited partial elasticity reduction. • Native purple and red corn flours demonstrated superior gel hardness and elastic dominance. • Processing method (29 %) and corn pigmentation (17.1 %) were primary differentiating factors in PCA. • Results enable strategic application of pigmented corn in food formulations with optimal functionality.