This study examines the effect of salts (0.5M NaCl or 0.25M CaCl2) and protein concentration (7.5-15%) on the gel-forming abilities of lentil (LPI), yellow pea (YPI), and faba bean (FPI) protein isolates. The chemical composition (protein, lipid, ash, and moisture), zeta potential (pH 1.5-7.0) and surface hydrophobicity (pH 7.0) of protein isolates were analyzed, along with their thermal and rheological properties. Morphologies of the gel networks were imaged using confocal laser scanning microscopy (CLSM). At pH 7.0, the surface hydrophobicity of YPI (84.8 arbitrary units, a.u.) was found to be lower than LPI (147.2 a.u.) and FPI (135.0 a.u.), whereas the surface charge for LPI, YPI, and FBI was -37.8, -28.4, -29.3 and mV, respectively. The minimum gelling concentration for LPI, YPI, and FPI were found 10%, 12.5%, 10% in distilled water; 7.5%, 12.5%, 10% in 0.5M NaCl solution; 7.5%, 10%, and 10% for CaCl2 solution, respectively. The gelation temperature was found to decrease with increasing protein concentrations and with the presence of salts. LPI and FPI produced firmer structures relative to YPI as evident by higher storage moduli. Network strength became stronger as the protein concentration increased or in the presence of NaCl or CaCl2. LPI and FPI also appeared to have a more ordered structure as evident by CLSM. Multiple endothermic peaks were determined in each protein sample associated with protein unraveling and network formation. Findings from this study showed the effect of salts and protein concentration on gel strength.
