Thermal and Mineral Sensitivity of Oil-in-Water Emulsions Stabilised using Lentil Proteins

Oil-in-water emulsion systems formulated with plant proteins are of increasing interest to food researchers and industry due to benefits associated with cost-effectiveness, sustainability and animal well-being. The aim of this study was to understand how the stability of complex model emulsions formulated using lentil proteins are influenced by calcium fortification (0 to 10 mM CaCl₂) and thermal processing (95 or 140 °C). A valve homogeniser, operating at first and second stage pressures of 15 and 3 MPa, was used to prepare emulsions. On heating at 140 °C, the heat coagulation time (pH 6.8) for the emulsions was successively reduced from 4.80 to 0.40 min with increasing CaCl₂ concentration from 0 to 10 mM, respectively. Correspondingly, the sample with the highest CaCl₂ addition level developed the highest viscosity during heating (95 °C × 30 s), reaching a final value of 163 mPa·s. This was attributed to calcium-mediated interactions of lentil proteins, as confirmed by the increase in the mean particle diameter (D[4,3]) to 36.5 µm for the sample with 6 mM CaCl₂, compared to the unheated and heated control with D[4,3] values of 0.75 and 0.68 µm, respectively. This study demonstrated that the combination of calcium and heat promoted the aggregation of lentil proteins in concentrated emulsions.