Protein nanovehicles produced from egg white. Part 2: Effect of protein concentration and spray drying on particle size and linoleic acid binding capacity

Abstract

In this work, the effect of egg white protein (EWP) concentration on linoeic acid (LA) binding capacity and particle size of heat-induced EWP nanovehicles (EWPn) was studied. Two heat treatment were applied at the following conditions: i) 80 °C, 10 min, pH 10.8, varying protein concentration between 0.85 and 3.41 % wt. and ii) 80 °C, 5 min, pH 11.4, varying protein concentration between 0.85 and 4.26 % wt. Turbidity and LA binding capacity were measured using absorbance at 400 nm. LA was taken as a model lipophilic compound. Particle size analysis was performed by means of DLS. Results indicated that both turbidity and average particle diameter (Z-Ave) increased linearly with protein concentration; although there is no clear tendency in volume based particle size distributions (PSDv). Particle size results indicated that nanosized particles (<100 nm) were obtained for both treatments (i and ii). Moreover, protein concentration had a negligible effect on LA binding capacity of EWPn. Finally, EWPn obtained at 80 °C, 5 min, pH 11.4 and 3.41 % wt. protein, were spray dried, obtaining a white fine powder (8.72 ± 0.13% moisture content). In general, PSDv and LA binding capacity of EWPn did not change after spray drying. Remarkably, results suggest that EWPn can be obtained by a simple process (involving dilution, centrifugation, pH adjustment, heat treatment and, optionally, spray drying) using egg white as a commercially available raw material.