pH Cycling-Induced Formation of Chickpea Protein–Casein Dual-Protein Complexes: Interaction Mechanisms, Structure, Function, and Bioactive Molecule Protection

Single proteins have certain limitations in terms of functional properties, while composite products combining plant and animal proteins offer a practical and sustainable strategy to address this issue. This study aims to establish a dual-protein complex, the pH cycling-induced chickpea protein (CP)-casein (CA) complex (pH-CP/CA), to load curcumin and enhance its functionality. Results showed that pH-CP/CA (CP/CA = 2:1, mass ratio) exhibited a smaller particle size and a higher absolute value of zeta potential. Hydrogen-bonding, electrostatic, and hydrophobic interactions drove the pH-CP/CA formation, resulting in improved solubility, emulsification, foaming, and thermal stability. Curcumin (Cur) was loaded in pH-CP/CA through pH cycling to construct the Cur-containing complex (pH-CP/CA-Cur). The pH-CP/CA-Cur achieved an encapsulation efficiency of 83.04% (w/w) and exhibited enhanced stability compared with Cur. Furthermore, its bioavailability reached 85.82% in the simulated digestion. This study demonstrates the role of pH cycling in fabricating dual-protein complexes and establishes their potential as nanocarriers for bioactive molecules.