Combined thermal and high pressure homogenization treatments for enhanced physical properties of lentil protein-stabilised emulsions

This study aims to interlink the colloidal properties of lentil protein emulsions formulated with protein suspensions pretreated with high pressure homogenization (HPH), thermal treatments (TT) and its combination (HPH+TT). Lentil protein suspensions were pre-treated with HPH (50 MPa), thermal treatment (120 °C for 60 s) or HPH followed by the TT. The physicochemical properties of these pretreated suspensions, as well as of emulsions prepared from them, were compared with those of an untreated sample. The particle size distribution of the suspensions was significantly reduced by HPH, with the volume-weighted mean diameter (D [4, 3]) decreasing from 3.63 μm (untreated) to 1.48 μm (HPH). TT and HPH+TT suspensions had a similar particle size distribution to the untreated sample, indicating a partial protein aggregation. The samples showed a transition from shear-thinning to near Newtonian behaviour when treated with TT and HPH+TT, which also enhanced their physical stability. The emulsion formulated with the pre-treated suspensions had a significantly lower particle size distribution compared to the untreated samples. Interestingly, the HPH+TT emulsion had the lowest particle size with a D [4, 3] of 1.07 μm and displayed the highest physical stability compared to the sample. The improved emulsion stability is likely due to enhanced enhanced physical properties in the protein suspensions, which increased their functionality and interfacial activity, leading to more effective stabilization of the oil droplets. These findings demonstrate that the combining HPH and thermal treatment can significantly improve the stability and functionality of high-solids lentil protein-stabilised emulsions, supporting their use in sustainable young child infant formula.