Cold-gelation-related functionality of hot-air-popped flours from pigmented popcorn (Zea mays var. 'Everta'), sorghum (Sorghum bicolor), and amaranth (Amaranthus sp.).

Hot-air popping promotes grain matrix reorganization and may enhance cold-gelation functionality in grain flours. This study evaluated the structural, techno-functional, and rheological properties of pigmented popcorn, sorghum, and amaranth flours after hot-air popping using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, pasting analysis, and rheology. Popping increased β-sheet (56%) in purple popcorn and reduced crystalline order (2.4% and 0%) in red sorghum and amaranth, respectively. Microscopy revealed expanded porous structures. These modifications improved water absorption (6.5%), swelling capacity (572%), and oil absorption (7%), and increased initial viscosity in yellow popcorn and amaranth (1.21 and 1.03 Pa•s, respectively), as well as viscoelastic behavior. Popcorn and sorghum showed pronounced structural reorganization associated with enhanced gel-forming potential. The results demonstrate that hot-air popping is an effective, low-energy process for modifying grain structure and promoting cold-gelation functionality, supporting the development of clean-label ingredients for food formulations requiring viscosity and texture enhancement under mild conditions.