Insight into conformation and foaming properties of RuBisCO-enriched Edible dock leaf protein concentrates

As the most abundant plant protein on Earth, RuBisCO represents a promising sustainable alternative to animal-derived ingredients. This study compared the pH-induced conformational changes and foaming properties of RuBisCO-enriched Edible dock leaf protein concentrate (RPI) extracted via an alkali-ultrafiltration method, with commercial protein isolates. The results demonstrated that RPI exhibited greater flexibility than other proteins under pH modulation. Dynamic light scattering revealed that at pH > pI (isoelectric point), RPI underwent a significant shift in zeta potential towards more negative values (shift from -8.63 mV to -23.65 mV, p < 0.05), indicating enhanced electrostatic repulsion. Concurrently, ANS-binding surface hydrophobicity decreased by 47.36 % (p < 0.05), while intrinsic fluorescence intensity surged 300 % at pH 9 (λex = 340 nm). These changes suggested reduced hydrophobic exposure and optimized microenvironments for aromatic residues. The decrease in turbidity further supported suppressed hydrophobic aggregation, likely due to increased electrostatic stabilization. The unique interfacial molecular arrangement of RPI, characterized by pH-induced flexibility and balanced hydrophobic/electrostatic interactions, formed mechanically stable films that sustained foam structures. Consequently, RPI exhibited superior foam capacity (FC: 110-140 %) and stability (FS > 85 % after 30 min) across pH 5-9, outperforming plant-based controls (soybean and pea protein isolates) and achieving performance comparable to animal-derived proteins (whey, egg white, and caseinate) under the same treatment conditions. The findyaiings establish RPI as a pH-adaptable, plant-based foaming agent and elucidate the structure-function relationship for tailored food applications.