Design and fabrication of a food-grade albumin-stabilized nanoemulsion

A food-grade biopolymer-emulsion delivery system was developed for improving or extending the functional performance of the bioactive components of food. Droplet size, rheological and interfacial measurements, scanning electron microscopy (SEM), thiobarbituric acid reactive substance (TBARS) assay and Fourier transform-infrared (FTIR) analysis were used to study the effect of sonication time and power, poly ethylene glycol (PEG) addition, heat treatment and oil fraction on physical and chemical stabilities of bovine serum albumin (BSA)-stabilized corn oil-in-water (O/W) emulsions prepared by ultrasonic emulsification. The findings showed that sonication power and time had significant effects on the reduction of mean droplet diameter to 75 nm in the presence of PEG. PEG acted as an enhancer of viscosity of the aqueous phase. PEG had negligible influence on the interfacial tension of the emulsion. An increase in the oil fraction of up to 20 wt% had no effect on the mean droplet diameter of BSA emulsion containing PEG. Mean droplet diameter of BSA emulsions that contained PEG 10000 and 300, increased to 170 and 250 nm, respectively, after 60 days of storage at 6 °C. FTIR analysis showed that the addition of PEG had no major influence on the secondary structure of BSA. The proportion of unadsorbed protein in the PEG-contained nanoemulsions was lower than that in emulsions without PEG. Based on TBARS content the oxidative stability of sonicated emulsions in the presence of PEG were less than other formulations.