The aim of this work was to build, to isolate and to characterize, core-shell microparticles composed of a core of thermally aggregated beta-lactoglobulin (beta-lg) covered by a shell of carboxymethylcellulose (CMC). The core-shell particles were obtained by mixing (beta-lg)(n) and CMC solutions at pH 7 and finally, decreasing the pH up to 4, promoting the adsorption of CMC on the protein core due their opposite electric charge. The core-shell microparticles were characterized by static laser light scattering (SLS), optical microscopy and atomic force microscopy (AFM). At pH 4, ( beta-lg)(n) showed a diameter similar to 200 nm, but after adding the polysaccharide had a diameter similar to 1 mu m. The microscopy corroborated the data obtained by SLS measurements. Core-shell microparticles could be isolated by lyophilization and potentially applied as a fat replacement and/or a delivery systems for encapsulated substances in food formulations. (C) 2014 Elsevier Ltd. All rights reserved.