Development of W/O emulsion for encapsulation of "Pitanga" (Eugenia uniflora L.) leaf hydroethanolic extract: droplet size, physical stability and rheology

The low chemical stability under environmental conditions of "Pitanga" leaf hydroethanolic extract (PLHE) can limit its application in industrial scale. It is known that this extract has high antioxidant and antimicrobial activities and that it must be stored under special conditions or encapsulated into W/O emulsions. The objective of this research was to encapsulate PLHE in a W/O emulsion, analyzing the effect of the concentration of the emulsifier and phase ratios on its droplet size, physical stability and viscosity. In general, the droplet size and stability of the W/O emulsions were affected by the concentrations of emulsifiers and phase ratios. The emulsion with a 20/80 W/O ratio and 3 g PGPR/100 g oil was chosen as the most stable formulation because they presented well distributed droplet sizes (unimodal distribution), the lowest D-3,D-2 (0.25 +/- 0.02 mu m), the highest physical stability at 60 degrees C and presented Newtonian behavior. In conclusion, the W/O emulsion is able to encapsulate PHLE and can be applied to thermal processed foods.