The development of milk functional foods including health-promoting green tea polyphenols represents a challenge for the food industry since the formation of protein-polyphenol complexes may affect both protein technological properties and polyphenols biological activity. The present work aimed at the characterization of complexes formed between green tea polyphenols and either beta-lactoglobulin (beta-lg) or caseinomacropeptide (CMP), as well as to evaluate how this complexation may impact on protein gelation and polyphenol antiproliferative activity against tumor cell lines. Particle size and charge of protein-polyphenol complexes depend on protein nature and pH. At pH 6 they had the smallest size and were soluble. The presence of polyphenols accelerated the gelation of both beta-lg and CMP, and mainly affected viscoelasticity of beta-lg gels. Polyphenol complexation by proteins did not inhibit its anti-proliferative activity. Moreover, they exerted a better performance on some particular tumor cell lines. (c) 2012 Elsevier Ltd. All rights reserved.44800809Universidad de Buenos AiresAgencia Nacional de Promocion Cientifica y TecnologicaConsejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina