Impact of Homogenization Speed on the Creaming Stability of Model Double (W 1 /O/W 2 ) Emulsions Prepared With Sunflower Oil

ABSTRACT The creaming stability of model double (W 1 /O/W 2 ) emulsions was analyzed on systems prepared with sunflower oil and varied homogenization speed (12,000, 18,000, or 24,000 rpm) in the second emulsification step. Comparative simple (O/W 2 ) emulsions were prepared under the same homogenization conditions. Particle size was decreased with increasing homogenization speed in both W 1 /O/W 2 and O/W 2 emulsions. However, W 1 /O/W 2 emulsions presented larger particle sizes than O/W 2 emulsions at the same homogenization speed, attributed to the higher viscosity of the oil phase (containing water droplets) in the former. The amount of dispersed aqueous (W 1 ) phase within oil globules in W 1 /O/W 2 emulsions was reduced at higher homogenization speed, leading to systems with lower viscosity due to the lower volume fraction of dispersed (W 1 /O) phase. After 1 day of storage, both W 1 /O/W 2 and O/W 2 emulsions showed a higher creaming rate at lower homogenization speed, attributed to the larger particle size. On the other hand, after 15 days of storage, a lower homogenization speed led to a lower creaming rate in W 1 /O/W 2 emulsions, while it still produced a higher creaming rate in O/W 2 emulsions. This result could be explained by the higher global density, viscosity, and volume fraction of dispersed (W 1 /O) phase, as well as the lower polydispersity of oil globules observed in W 1 /O/W 2 emulsions prepared with lower homogenization speed. The obtained results provide a better understanding of the creaming stability of W 1 /O/W 2 emulsions, which could be relevant for the preparation and utilization of such systems.