The aim of this work was to formulate O/W/O multiple emulsions containing açaí oil as a model system and to evaluate their physical stability and in vivo Sun Protection Factor (SPF). Multiple emulsions are complex dispersion systems, known also as, "emulsions of emulsions". These emulsion systems, have significant potential in the cosmetic industry. Euterpe oleracea Mart., Arecaceae, popularly known in Brazil as "açaí", is an economically important plant. Açaí oil has been used as antioxidant and as anti-inflammatory activities. The multiple emulsions were prepared using a two-step procedure. The investigated formulations were characterized and their stability over time was evaluated by preliminary and accelerated stability. O/W/O multiple emulsions containing the same concentration of sunscreens with and without açaí oil were evaluated by the International Sun Protection Factor Test Method. The samples containing 70% (w/w) of primary emulsion, 5% (w/w) PEG-30-dipolyhydroxystearate, 10% (w/w) of açaí oil and 5% (w/w) of sucrose polybehenate have been found to be stable. The rheological measurements revealed that the samples exhibited non-Newtonian pseudoplastic flow behavior and thixotropy. To conclude, no statistical difference could be observed on the in vivo SPF to both multiple systems with or without açaí oil.
açaí; Euterpe oleracea; in vivo sun protection factor; multiple emulsions
