Producción Científica ; Quercetin is a strong antioxidant flavonoid with several bioactive properties such as anti-inflammatory and anticarcinogenic activities, becoming an interesting compound to be incorporated into pharmaceutical, cosmetic or food products. However, these applications are limited by the low bioavailability of this flavonoid. Quercetin is poorly soluble in aqueous media, such as gastrointestinal fluids, being also degraded by gut flora. Thus, it is necessary the development of quercetin's formulations capable of improving its water solubility resulting in increased bioavailability and thus higher biological activity of this compound. The aim of the present work was the formulation of quercetin using three distinct natural origin surfactants, namely OSA-starch, Lecithin and b-glucan, by precipitation from a pressurized ethyl acetatein- water emulsion. Formulations of quercetin with encapsulation efficiencies up to near 76% and a micellar particle size in the range of nanometers were obtained using lecithin. An improved antioxidant activity (3-fold higher per unit mass of quercetin) was also observed in these formulations, demonstrating that lecithin is a good emulsifier for the encapsulation of quercetin. Furthermore, the addition of glycerol as co-solvent increased the colloidal stability of the suspension and the encapsulation efficiency of the flavonoid. ; Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA225U14)