Co-Refolding of Pea Protein and C-Phycocyanin for Multifunctional Hydrocolloids at pH 5

Pea proteins exhibit a low net charge near their isoelectric point (∼5), limiting their solubility and functionality. To address this limitation, we explored a pH-driven co-refolding method using C-phycocyanin, a highly hydrophilic protein that undergoes pH-dependent disassembly and reassembly. This process facilitated the formation of pea protein-C-phycocyanin hybrid hydrocolloids with enhanced stability and solubility at pH 5. The relative solubility increased from 3.9% to 68.7%, and the denaturation temperature rose from 84.2 to 129.7 °C. Structural analysis revealed the presence of large globular multimers, including at least phycocyanin nonamers complexed with legumin. Compared with C-phycocyanin alone, the hybrids enhanced the color retention of the tetrapyrrole chromophore under heat by 2.9% and under UV irradiation by 23.9%. Overall, this study demonstrates a simple and effective method to create functional plant-protein-based ingredients suitable for acidic food and beverage applications.