Interactions Between Sodium Caseinate and Polyglucose in Aqueous Solutions
Biopolymers interactions have been widely studied to understand their impact on the texture and shelf life of food products. The effect of addition of sodium caseinate on the physical and rheological properties of solutions containing poly-glucose compounds (dextran, maltodextrin), at neutral pH and varying biopolymer concentrations, have been investigated. Through a combination of characterization tools, the properties for the mixed biopolymer systems are correlated to the nature of the interactions between the two biopolymers involved. For systems containing sodium caseinate and dextran, biopolymer incompatibility, leading to phase separation, was observed as there were minimal changes detected in the particle size and the turbidity of the mixed systems, as compared to the individual biopolymer solutions. Weak associative interactions between the biopolymers were also confirmed through studies using Isothermal Titration Calorimetry (ITC). For systems containing high concentrations of the two biopolymers, upon centrifugation, phase separation was confirmed using a combination of viscometer, carbohydrate and protein analysis, with the bottom phase found to be protein-rich, while the top phase, the polysaccharide-rich phase. In case of systems containing sodium caseinate and maltodextrin, at lower concentrations of sodium caseinate, a monophasic system was observed, while at higher concentrations of maltodextrin and sodium caseinate, a biphasic system, resulting from incompatibility between the biopolymer species, was confirmed using a combination of chemical analysis and viscometer studies. This work has demonstrated, using a model system of sodium caseinate and dextran/maltodextrin that thermodynamic incompatibility between the conformationally dissimilar species promotes an early phase separation in solution.
Campanella, Purdue University.
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