Microemulsions are thermodynamically stable, transparent, isotropic single-phase mixtures of two immiscible liquids stabilized by surfactants (and possibly other compounds). The assortment of very different microstructures behind such a univocal macroscopic definition is presented together with the experimental approaches to their determination. This tutorial review includes a necessary overview of the microemulsion phase behavior including the effect of temperature and salinity and of the features of living polymerlike micelles and living networks. Once these key learning points have been acquired, the different theoretical models proposed to rationalize the microemulsion microstructures are reviewed. The focus is on the use of these models as a rationale for the formulation of microemulsions with suitable features. Finally, current achievements and challenges of the use of microemulsions are reviewed.

The system made by water, isooctane and a blend of Sodium dioctyl sulfosuccinate (AOT) with its more hydrophilic homologue sodium dihexyl sulfosuccinate (SDHS) can give raise to Winsor I, III and II equilibria at room temperature by slight changes in salinity. The phase transitions have been tracked using diffusion NMR, and solubilized volume fractions while small‐angle X‐ray scattering (SAXS) provided insight into the characteristic lengths (ξ) within the microemulsions' structures. Our findings reveal a peculiar linear correlation between the reciprocal of these characteristic lengths (ξ⁻¹) and the HLD values. For HLD <0, ξ⁻¹ decreases linearly with HLD with a slope = −0.0056 Å⁻¹ but just above HLD = 0 the slope reverses (+0.0056 Å⁻¹) and ξ⁻¹ increases linearly with HLD demonstrating that the HLD reflects the direction of interfacial curvature. However, at the optimal composition where the curvature is null and HLD = 0, the linear trends observed for ξ⁻¹ below and above HLD = 0 converge at a ξ⁻¹ value that is significantly greater than 0. This indicates that HLD is a measure of the interface/volume ratio and not of the interface curvature. This work aims to deepen the understanding of the relationship between the semi‐empirical HLD equation and the spontaneous curvature of microemulsions.

Digestion pathways of plant proteins are of high relevance to optimize bioavailability and allergenicity profiles of sustainable and vegan food products. Understanding the structural breakdown of solid food presents a particular challenge, due to the complexity to realize a good model system suitable for comprehensive multi-technique characterization under realistic conditions. We used a microfluidic chip to study the structural evolution during in-vitro digestion of solid gels from pea proteins. The gel structure was probed in-situ combining confocal microscopy, small-angle neutron and X-ray scattering using the same experimental platform. SDS-PAGE analysis was performed on related solution and gel samples subjected to different digestion times. Combining multiple techniques we reach a multi-scale picture of gel digestion, revealing the breakdown of a more homogeneous gel into more open connected domains with hierarchical internal structures. SDS-PAGE outlines effects of processing on resulting digestion pathways. As central result, we observe a clear two-step digestion process across techniques, switching at about 8-10 min from the initial response to long-term digestion. Overall, the presented methodology holds promise for detailed structural information in future studies aimed at developing new foods with optimized mechanical, nutritional value, and reduced allergenicity.