Infrared heating modified rheological behavior of pea flour to enhance expansion in extruded puffed snacks

Peas are gaining attention as nutritious and sustainable grains for the snack industry. However, the high protein and dietary fiber contents of pea flour (PF) often limit its expansion during extrusion, resulting in dense products with suboptimal texture. This study investigated infrared (IR) heating as an effective thermal treatment to improve the performance of PF in extruded snack production. After tempering to 24%-25% moisture for 24 and 48 h, pea seeds were subjected to IR heating to reach a surface temperature of 125 °C-130 °C. After milling, the resulting flours were characterized for compositional and functional properties and subsequently extruded into puffed snacks. IR treatment not only gelatinized starch but also reduced the amylose content of PF, suggesting molecular breakdown of starch. Rheological analysis of PF cooked and held at 140 °C revealed that 48 h IR-treated PF exhibited higher viscoelastic moduli and lower loss tangent (tan δ) than the other samples, indicating the formation of a more cohesive melt structure. Additionally, RVA results demonstrated that IR-treated PF required elevated heating temperatures to develop higher viscosity, reflecting improved resistance to high-temperature processing. These structural modifications enhanced the extrusion performance of PF. Snacks produced from 48 h IR-treated PF exhibited a higher expansion ratio (4.5 versus 3.5), reduced bulk density (50.0 versus 56.5 g/L), lower normalized hardness (162.8 versus 212.0 g/specimen), and greater crispness (186.5 versus 168.2) than the control. Overall, IR treatment effectively tailored the structural and rheological properties of PF, thereby improving the expansion and texture of pea-based extruded snacks.