Fermentation-associated restructuring of chickpea proteins modulates interfacial functionality and lipid-phase...

Native pulse proteins often require structural modification to improve their functionality in artificial fat (AF) systems. This study investigated the structure-function associations between Rhizopus oryzae solid-state fermentation of chickpeas and the performance of coconut oil-based AF systems. Chickpeas were fermented for 0, 24, 48, and 72 h, and fermentation-associated differences in protein molecular profile, secondary structure, thiol-disulfide state, solubility, and surface hydrophobicity were evaluated. The resulting chickpea-derived fractions were incorporated into AF systems, which were characterized in terms of emulsion performance, rheological behavior, crystalline organization, and thermal transitions. Increasing fermentation time was accompanied by a decrease in α-helix content from 4.75% to 1.70% and an increase in β-sheet content from 27.95% to 34.25%, together with non-linear changes in thiol-disulfide balance. Among the tested conditions, 24 h fermentation provided the most favorable combination of protein solubility and surface hydrophobicity. Correspondingly, AF-24 h exhibited the highest emulsion activity index (7.75 m²/g), greater absolute zeta potential, favorable thermal retention of apparent emulsion activity, and the strongest bulk rheological response. X-ray diffraction and differential scanning calorimetry further revealed fermentation-dependent differences in the crystalline organization and crystallization-melting behavior of the dispersed coconut oil phase. In contrast, the 72 h fermented fraction showed lower protein dispersibility and less favorable emulsion, rheological, and lipid-phase characteristics. Overall, these findings indicate that controlled R. oryzae fermentation can modify the functional state of chickpea-derived fractions and is associated with the structural performance of coconut oil-based AF systems, supporting their potential as plant-derived structuring components for artificial fat applications.