Structure, functional and physicochemical properties of lotus seed protein under different pH environments

The present study investigated the structure, functional and physicochemical properties of lotus seed protein (LSP) under different pH environments. The structures of LSP were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy (FTIR), zeta potential, particle size distributions, free sulfhydryl and rheological properties. The functional and physicochemical properties of LSP were characterized by color, foaming property, emulsification property, solubility, oil holding capacity, water holding capacity, differential scanning calorimetry analysis and surface hydrophobicity.

LSP was mainly composed of eight subunits (18, 25, 31, 47, 51, 56, 65 and 151 kDa), in which the richest band was 25 kDa. FTIR results showed that LSP had high total contents of α-helix and β-sheet (44.81-46.85%) in acidic environments. Meanwhile, there was more β-structure and random structure in neutral and alkaline environments (pH 7.0 and 9.0). At pH 5.0, LSP had large particle size (1576.98 nm), high emulsion stability index (91.43 min), foaming stability (75.69%) and water holding capacity (2.21 g g^-1), but low solubility (35.98%), free sulfhydryl content (1.95 μmol g^-1) and surface hydrophobicity (780). DSC analysis showed the denaturation temperatures (82.23 °C) of LSP at pH 5.0 was higher than those (80.10, 80.52 and 71.82 °C) at pH 3.0, 7.0 and 9.0. The analysis of rheological properties showed that LSP gel had high stability and great strength in an alkaline environment.

The findings of the present study are anticipated to serve as a valuable reference for the implementation of LSP in the food industry. © 2024 Society of Chemical Industry.