Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The association of gellan gum and nonionic surfactant in the gel formation was explored in systems with high biopolymer concentration (3% w/w). Gels formed with different concentrations of polysorbate 80 (0-60% w/v) and pH (3.0 and 5.0) were evaluated from their microstructure, mechanical and theological properties. The high concentration of polysaccharide in water at more acidic pH (3.0) favored the aggregation of molecules, producing harder gels even at high temperatures. The thermal theological measurements showed two distinct behaviors which depending on the predominance of polysaccharide or surfactant in the systems. The gellan gum properties were predominant at lower surfactant concentrations. However, the surfactant micelles could enhance the linkage between the macromolecules through the few remaining hydrophobic sites of the biopolymer and consequently increase the gel strength that presented strain-hardening behavior. As the surfactant concentration was increased to 30% (w/w), different slopes in the theological curves were observed. They were attributed to the structuration of the polysorbate. At higher concentration of polysorbate, the surfactant prevented the gellan gum aggregation and the gum did not exert influence on the theological behavior, which was related to the surfactant structuration. The surfactant self-assembly produced weaker gel-like structures than the gellan network, presenting a strain-weakening behavior. Thus, results suggest that depending on the medium conditions, gellan-polysorbate 80 interaction could produce different gels with different technological properties. (C) 2013 Elsevier Ltd. All rights reserved.541501507Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)FAPESP [EMU 09/54137-1]CNPq [Universal 479459/2012-6]