Molecular structure characteristics,functional parameters and in vitro protein digestion of pressure‐cooked soya bean flours with different amounts of water

When a food product is cooked at high temperature with different proportions of water, the differential degradation that occurs in the molecular structure promotes changes in their functional characteristics. In this study, water and soya bean flour (dry base) were mixed in different ratios (3:1, 2:1, 1:1, 0.25:1 and 0:1) and pressure cooked at 130 °C, 1.5 kg cm^?2 for 30 min, cooled down to 40 °C and air dried for 24 h. Protein changes due to thermal process were determined with the ATR‐FTIR, as well as some functional parameters and in vitro protein digestibility. At higher water:soya bean flour ratios (3:1 and 2:1), the protein digestibility increased due to denaturation of tertiary structures, while urease activity (UA) and the functional characteristics of water absorption index (WAI) and water solubility index (WSI) decreased. Pearson's correlation analysis revealed that molecular changes on amide I, II and in α‐helix: β‐sheet ratios were directly related with the amount of added water.