Physicochemical properties of high-pressure treated lentil protein-based nanoemulsions

Abstract

The emulsifying properties of pulse proteins offer the possibility to provide functionality to colloidal food systems like nanoemulsions. The objective was to obtain stable lentil nanoemulsions through High-Pressure Homogenization (HPH) (50–300 MPa) using different number of homogenization passes (1–3) and emulsifier:oil ratios (1:1, 1:2, 2:1). Oil-in-water nanoemulsions were characterized through particle size distribution, mean droplet size, polidispersity index (PdI), ζ-potential, interfacial tension (IT), stability against creaming, and flow behavior. HPH >100 MPa changed particle size distribution of 1:1 lentil nanoemulsion from multimodal to bimodal, regardless of homogenization passes number. Two homogenization passes and ratios of 1:1 and 2:1 improved reduction of droplet size (587–149 nm) and PdI (0.821–0.168), with no difference between those ratios. ζ-potential values were lower than −30 mV, which can be considered as a stable emulsion. As emulsifiers, lentil proteins decreased IT of water-oil interphase from 16.5 to <7.0 mN/m, regardless pressure treatment applied. Nanoemulsions showed pseudoplastic characteristics at all experimental conditions evaluated. HPH decreased ƞapp, and higher ƞapp were observed with 2:1 ratio. Stable lentil nanoemulsions can be obtained by using 1:1 emulsifier:oil ratio and HPH above 200 MPa with two homogenization passes, which could be used as novel food systems.