Multi-scale structural changes of starch and proteins during pea flour extrusion

The design of high-protein expanded foods is still a challenge, likely due to the reactivity of protein components under thermomechanical treatment and its effect on extrudate structure and texture. Material temperature governs concomitant starch and protein changes during pea flour extrusion. Protein insolubilization, mainly due to SS bonds, is triggered at T ≈ 125 °C, and contributes to expansion by morphology changes. CSLM micrographs of two samples extruded under similar conditions show different expansion (density ρ*) and morphology of amorphous starch/protein aggregates. These differences are probably due to slight variations in specific mechanical energy (SME), moisture content (MC) or strain at the die.185