Naringenin (Nn) and Quercetin (Q) have numerous health benefits particularly due to their antioxidant properties However their low solubility bioavailability and stability limit their use as components for functional foods nutraceuticals and pharmaceutical agents In this research Nn- and Q-microparticles were produced by a spray-drying process using a combination of cellulose acetate phthalate (CAP) as coating gastroresistant polymer and swelling or surfactant agents as enhancers of dissolution rate Raw materials and microparticles produced were all characterized by particle size analysis differential scanning calorimetry X-ray diffraction and imaged by electron and fluorescence microscopy During 12 months storage stability was evaluated by analyzing drug content HPLC and DSC profiles as well as antioxidant activity (DPPH test) In vitro dissolution tests using a pH-change method were carried out to investigate the influence of formulative parameters on flavonoid release from the microparticles Presence of a combination of CAP and surfactants or swelling agents in the formulations produced microparticles with good resistance at low pH of the gastric fluid and complete flavonoid release in the intestinal environment The spray-drying technique and the process conditions selected have given satisfying encapsulation efficiency and product yield The microencapsulation have improved the technological characteristics of the powders such as morphology and size have given long-lasting storage stability and have preserved the antioxidant properties (C) 2010 Elsevier Ltd All rights reserved