CONICET | Buscador de Institutos y Recursos Humanos

Foods contain proteins (PT) and polysaccharides (PS) in form of complex multicomponent mixtures, and so it is often difficult to disentangle the separate roles of the biopolymers in terms of their functional properties, responsible for the structure, mechanical, textural, and other physicochemical properties. These functional properties are affected by the interaction between biopolymers and other components of food systems. Therefore, the study of the interactions in PT-PS mixtures and their adequate formulation may contribute to the elaboration of food products with special microstructure, rheological, and textural characteristics. Segregative phase separation by thermodynamic incompatibility is commonly observed in ionic and nonionic biopolymer mixtures. At low biopolymer concentrations, the mixture remains a single phase. However, above a critical concentration ratio, PT-PS mixtures form a system with two separated phases, in which each phase is enriched in one of the biopolymers. The limited thermodynamic compatibility between PT and PS may be exploited to obtain micro/nanoparticles, by controlling the size of the aggregates (e.g. by selecting the PS, the temperature, and the relative concentrations of PT and PS). On the other hand, a process that has gained the attention of the food industry is the acidification of milk by addition of glucono-delta-lactone (GDL). It is known that the gelation process rate affects the hardness and elasticity of the resulting acid gels. In PT-PS mixtures, the presence of PS may produce changes in the protein gel formation kinetics, leading to the formation of gels with different microstructural and textural characteristics. This behavior may be due to the competition between the gelation process and the phase micro-separation generated by thermodynamic incompatibility. In this work, PT and PS assayed were bovine sodium caseinate (NaCAS) and soy protein isolate (SPI), and locust bean gum (LBG) and tara gum (TG), respectively. For each PT-PS mixture, thermodynamic incompatibility was analyzed. Besides, the effect of the presence of PS on the PT acid gels formation, the textural and the microstructure characteristics of acid gels were studied. In general, the presence of PS affected the formation and the microstructure of protein acid gels and, at a certain ratio of concentrations, protein microparticles were obtained. These microparticles may be formed due to a competition between the kinetics of phase separation and the acid gelation process. Under these conditions, these acid gels present different microstructural and textural characteristics.

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