Effects of soybean-oil and emulsifiers mixture on rheological properties of oil-in-water emulsions

The effects of soybean-oil and emulsifiers mixture on rheological properties of oil-in-water emulsions were investigated. Polysorbate-80 and sorbitan-monooleate in the ratio 1:3 were added to stabilize a soybean-oil emulsion by high-pressure homogenization at 50 and 100 MPa. Particle size and rheological properties were measured. The z-average size value showed all the droplets ranging from 295.5 to 302.3 nm. The emulsions were Newtonian and non-Newtonian pseudoplastic at 50 MPa, although at 100 MPa exhibited a Newtonian behavior, preferably. The highest concentrations of soybean-oil and emulsifiers mixture showed semi-solid emulsions (at 50 MPa), and the lower concentrations of soybean-oil and emulsifiers mixture, showed semi-solid emulsions (at 100 MPa), however, elastic character predominated over viscous character (G’>G’’), for both pressures. In conclusion, the emulsion systems were nanoemulsions and their droplet size distribution was bimodal. The nanoemulsions had a non-Newtonian behavior for both pressures, although at 100 MPa the emulsions were Newtonian.