The sunflower oil in water nanoemulsions were prepared using the high pressure homogenization (HPH) technique. Pre-emulsions were obtained by high speed stirring using an Ultra Turrax T25 (IKA Labortechnik, Jahnke und Kunkel, Germany) at 24,000 rpm for 5 min. Then, the pre-emulsions were passed 5 times through an orifice high pressure homogeniser Nano DeBEE Electric Benchtop Laboratory (BEE International, USA) at 300 MPa. The emulsion temperature was reported immediately after processing at 4 ◦C by means of a heat exchanger placed downstream of the homogenizing valve.
The 4 different nanoemulsion formulations tested were all characterized by similar lipid phase composition (2% antimicrobial compound and 8% sunflower oil) and different emulsifier composition and fraction. In particular, nanoemulsions based on (a) 3% lecithin, (b) 3% pea proteins, (c) 1% sucrester and (d) the combination of 0.5% glycerol monooleate and 0.5% Tween 20 were prepared.