Establishing structure to function relationship of monoolein liquid crystalline structures

The structuring of foods with liquid crystals (LCs) has been investigated for decades, e.g., in the development of tablespreads or for bioactive compound encapsulation. Here, monoolein LC microstructure and rheology were characterised as a function of temperature and composition. LC structure was assessed using small angle X-ray scattering (SAXS) and polarised light microscopy. Small and large deformation rheology was characterised using frequency and amplitude sweeps, large amplitude oscillatory shear tests, and strain rate frequency superposition (SRFS). Initially, we characterised a number of monoolein-water binary phase transitions associated with lamellar, cubic, and hexagonal mesophases. Frequency sweeps revealed that the cubic phases had the highest elasticity followed by the lamellar and hexagonal phases. The stiffening and thickening ratios, extracted from Lissajous-Bowditch plots, were used to quantify intra-cycle non-linearities associated with the oscillatory rheology responses. The cubic phases displayed abrupt yielding with more pronounced stiffening and thinning behaviour compared to the others. Each LC phase displayed unique rheological behaviour upon large deformation and, by linking rheology with SAXS and composition, we showed that their symmetry defined their rheology. This work serves as the foundation for on-going efforts that explore the integration of a discrete particle phase within these mesophases in order to develop high-performance food products.