Interfacial Rheological Study of β-Casein/Pectin Mixtures at the Air/Water Interface

Abstract

Colloidal food products, such as emulsions, foams, gels, and dispersions, are complex systems that need the presence of stabilizing agents to enable their formation and provide stability. Proteins are often used for food foams and emulsions because of their ability to lower interfacial tension and make viscoelastic interfaces. Generally, to improve the resistance against rupture, polysaccharides are used in association with the proteins. Pectin is a complex polysaccharide that can help to stabilize foams or emulsions. This work aims at studying the mechanical resistance of the interface formed by mixtures of β-casein and pectin at high and low methoxylation degrees at the air/water interface using dilatational and shear kinematics. Frequency sweep tests, in the linear region, were performed in shear at different aging times and in dilatational mode, and the rheological data were analyzed. The transient data of the surface tension were analyzed by kinetic models to obtain the characteristic rates of the interfacial phenomena. The kinetic mechanisms of the protein/pectin mixed systems are controlled by protein and show a weak gel behavior for short aging times. The interfaces obtained with both pectins in a mixture with β-casein evolved with time, gelling and showing a solid-like behavior at concentrations of 1 and 10 g/L and after 3.5 h of aging time. The interfacial shear trend obtained suggests a good stabilizing effect of the pectins from citrus with long aging times.

Dilatational and Shear Interfacial Properties of Pea Protein Isolate Systems with Transglutaminase at the Air–Water Interface

“…In particular, β-casein exhibits an equilibrium value of 45 mN/m, suggesting an interfacial effect similar to the PPI investigated. Notably, both proteins reach saturation at a similar concentration [42]. Also, for ovalbumin protein, the comparison with the literature showed a similar surfactant effect and a similar concentration for full surface coverage [27].…”

“…In particular, the surfactant effect of PPI is similar to soy proteins, which show a surface tension of 40 mN/m at saturation concentration [7]. The surfactant effect of PPI is good if compared with animal proteins such as ovalbumin or casein [27,42]. In particular, β-casein exhibits an equilibrium value of 45 mN/m, suggesting an interfacial effect similar to the PPI investigated.…”