Formation, Structure, and Functionality of Interfacial Layers in Food Emulsions

Abstract

Emulsions, i.e., the dispersion of liquid droplets in a nonmiscible liquid phase, are overwhelmingly present in food products. In such systems, both liquid phases (generally, oil and water) are separated by a narrow region, the oil-water interface. Despite the fact that this interface is very thin (in the nanometer range), it represents a large surface area and controls to a great extent the physicochemical stability of emulsions. This review provides an overview of the aspects that govern the composition, structure, and mechanical properties of interfaces in food emulsions, taking into account the complexity of such systems (presence of numerous surface-active molecules, influence of processing steps, and dynamic evolution due to chemical changes). We also review methods that have conventionally, or recently, been used to study liquid-liquid interfaces at various scales. Finally, we focus on the link between interfacial properties and the physical, chemical, and digestive stability of emulsions at different levels and point out trends to control stability via interfacial engineering.

Strategies for structuring diverse emulsion systems by using wood lignocellulose-derived stabilizers

“…Depending on the morphology and electrostatic properties of the interfacial layer, droplets can be protected against coalescence and flocculation. 24 Furthermore, the mobility of droplets can be regulated by adjusting the viscosity of the continuous phase. 21 In o/w emulsions, this can be done with macromolecular hydrocolloids; entangling them in an aqueous environment entraps the droplets and prevents them from creaming/undergoing sedimentation and collision.…”

Dynamic Measurements with the Bicone Interfacial Shear Rheometer: Numerical Bench-Marking of Flow Field-Based Data Processing

“…The torque balance equation for the ISR rotor yields Equation (6), which relates the complex amplitude ratio to, both, the Boussinesq number and, implicitly, the velocity amplitude function g * (r,z):…”

“…Then, Equation 7was used to obtain a new calculated value of the Boussinesq number, Bo * calc , and this new value of the Boussinesq number was re-injected into the Boussinesq-Scriven boundary condition, Equation (5). Solving the hydrodynamic problem again (Equations (3)-(5)), a new flow field configuration (a new complex velocity amplitude function) was obtained, which allowed us to compute an iterated value of the complex amplitude ratio through Equation (6). This procedure was repeated until convergence according to condition Equation (8).…”

“…Systems such as tear film, the lung's internal fluid film, cell membranes, foams, and emulsions constitute examples of complex interfacial fluid systems whose dynamical properties play a crucial role regarding their function or utility. Indeed, knowledge of the mechanical properties of such fluid interfacial systems is an essential factor in the development of medical therapies in lung [2] or eye diseases [3], or in the stability and performance of industrial products in the food [4], personal care [5,6], and oil recovery sectors [7].…”

Nanostructured Lipid-Based Delivery Systems as a Strategy to Increase Functionality of Bioactive Compounds

“…On one hand, steric stabilisation occurs when oil droplets are coated with biopolymers that provide a layer around them, which is thick enough to overcome attractive forces between droplets. On the other hand, charges of the stabilisers covering the oil droplets contribute to the electrostatic stabilisation, which avoids that the oil droplets come close to each other [39]. Apart from biopolymer concentration, the pH of the solution needs to be controlled during all stages of the preparation process, so that the biopolymers are charged enough to avoid destabilisation processes [38].…”