Abstract
The formation of electrostatic protein-polysaccharide multilayers has attracted attention for the design of fluid interfaces with enhanced stability and functionality. However, current techniques are often limited to measuring final multilayer properties. We present an interfacial shear rheology setup with simultaneous subphase exchange, allowing the transient measurement of biopolymer multilayers by their viscoelasticity. The successive and simultaneous adsorption of β-lactoglobulin (β-lg) and low-methoxyl pectin were investigated at the n-dodecane/water interface at pH 4. The successive injection of pectin increased the viscoelasticity of an adsorbed β-lg layer by electrostatic complexation. On the other hand, simultaneous adsorption impeded adsorption kinetics and interfacial layer strength due to complexation in the bulk phase prior to adsorption. Neutron reflectometry at the air-water interface confirmed the formation of an initial β-lg layer and electrostatic complexation of a secondary pectin layer, which desorbed upon pH-induced charge inversion. The layer formed by simultaneous adsorption mainly consisted of β-lg. We conclude that protein-polysaccharide complexes show limited surface activity and result in a lower effective protein concentration available for adsorption.
Highlights
The stabilization of fluid interfaces by proteins is a common approach in colloid and interface science
We introduced an interfacial shear rheology setup with simultaneous subphase exchange, allowing the transient measurement of biopolymer multilayers by their viscoelasticity
Thereby, we could demonstrate that the successive adsorption of pectin to an established b-lg layer increases its interfacial layer strength, whereas simultaneous adsorption impedes adsorption kinetics and viscoelasticity compared to pure b-lg layers
Summary
The stabilization of fluid interfaces by proteins is a common approach in colloid and interface science. Proteins adsorb at the air/water (A/W) or oil/water (O/W) interface, induce a decrease in interface tension, and form a viscoelastic interfacial network.[1] The successive adsorption of a polysaccharide has emerged as a promising approach to improve the performance of protein stabilized interfaces, such as increased resistance against heat and ionic strength,[2,3] applicability in a broad pH-range,[3,4] increased interfacial moduli,[5] or stability under gastric conditions.[6,7]. Interfacial rheology measurements are usually restricted to measuring final layer properties, stressing the need for transient interfacial rheology measurements during multilayer formation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
