β-lactoglobulin stabilized nanemulsions--Formulation and process factors affecting droplet size and nanoemulsion stability.

To avoid the toxicological concerns associated to synthetic surfactants, proteins might be an alternative for the stabilization of pharmaceutical nanoemulsions. The present study investigates the use of β-lactoglobulin (β-lg) to stabilize oil in water biocompatible nanoemulsions intended for a pharmaceutical use and prepared by high pressure homogenization (HPH). The effects of composition (nature and weight fraction of oil, β-lg concentration) and of process parameters (pressure and number of cycles) on the droplet size and on the stability of nanoemulsions were thoroughly assessed. The nanoemulsions prepared with β-lg at 1 wt% and with 5 wt% Miglyol 812 (the oil with the lowest viscosity) displayed a relatively small particle size (about 200 nm) and a low polydispersity when a homogenization pressure of 100 MPa was applied for 4 cycles. These nanoemulsions were the most stable formulations over 30 days at least. Emulsification efficiency of β-lg was reduced at higher homogenization pressures (200 MPa and 300 MPa). The effect of HPH process on the interfacial properties of β-lg was evaluated by drop shape analysis. This treatment had an effect neither on the interfacial tension nor on the interfacial dilatational rheology of β-lg at the Miglyol 812/water interface.