Protein-driven multiscale structural evolution and oil absorption in Tigernut (Cyperus esculentus L.) starch during...

Understanding protein-driven structural modifications in starch during thermomechanical processing is essential for developing functional foods with tailored lipid profiles. This study elucidates how tigernut protein regulates the structural evolution and oil absorption behavior in tigernut starch under synergistic thermal-pressure conditions (80-170 °C, 20-60 MPa). The key findings demonstrate that, temperature-pressure coupling induces structural changes across three levels: significant granular expansion evidenced by 2.7-4.0 times volumetric increase relative to protein-free controls; crystalline disassembly with crystallinity loss up to 21.3 % and complete A-polymorph dissolution at 170 °C; molecular reorganization confirmed by short-range order enhancement (R_1047/1022: 1.76 % ∼ 15.12 % at 80 °C; 3.39 % ∼ 6.67 % at 170 °C) and double helix stabilization (R_995/1022: 16.25 % ∼ 18.52 % at 80 °C; 7.69 %-11.11 % at 170 °C). These coordinated modifications generate compact starch-protein matrices that reduce total oil absorption by 40.33 % ∼ 60.81 % and apparent oil content by 65.29 % ∼ 66.87 % at 80 °C. Mechanistic analysis reveals that protein-mediated restructuring imposes multidimensional spatial constraints limiting oil penetration through starch granule expansion, amorphous region regulation and hydrophobic site optimization. This fundamental understanding offers new insights for designing starch-based food systems with controlled lipid retention through precision processing.