The critical role of protein: linking concentration-defined structure to texture modification in pea starch-quinoa...

This research optimized pea starch (PS)-quinoa protein (QP) composite hydrogels using single-factor experiments and response surface methodology. The optimal conditions (98 °C, 35 min, PS/QP 10,2.4) yielded a water-holding capacity (WHC) of 76.71%. Crucially, a concentration-dependent mechanism was revealed, with 2.4% QP identified as a critical threshold. Below it (1-2% QP), competitive hydration formed fibrous networks, with reduced relative crystallinity (21.91% to 18.65%) and peak hydrophobic interactions (59.01° contact angle). Conversely, exceeding 2.4% protein self-aggregation triggered phase separation and network disruption, decreasing relative crystallinity (11.58%) and WHC (61%). At 2.4% QP, hydrogen bonding, electrostatic repulsion (zeta potential: -15.37 mV) and hydrophobic interactions acted synergistically to achieve a maximized WHC (76.71%) and optimized textural softness (1.514 N hardness), thereby complying with Level 4 (pureed) of the International Dysphagia Diet Standardisation Initiative framework for dysphagia management. This study provides a rational framework for engineering texture-modified foods by controlling protein-starch interactions.