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This thesis seeks to expand the knowledge on fluid gels and hydrocolloid tribology from a microstructural perspective. This was based on recent research highlighting the significance of tribology for in-mouth fat-related textural analysis during oral processing and the use of hydrocolloids, including fluid gels, for the development of reduced fat liquid and semi-solid foods. This thesis considers the control of fluid gel microstructures and the influence of hydrocolloid microstructure on material properties and lubrication. It is shown that the microstructure of a fluid between two-rubbing surfaces determines the tribological response which cannot necessarily be predicted from that fluid’s rheology. The microstructure of foods is therefore important in determining textural attributes, and tribology is an important field to study alongside rheology for the designed formulation of low-fat foods with acceptable mouth-feel. Particles of kappa-carrageenan fluid gels are shown to form aggregated percolated networks at low volume fractions and to have rheological properties between that typical for linear-polymers and hard-spheres. This behaviour is suggested to result from the particles having ‘hairy’ structures, that is, disordered polymer chains, resultant from a disruption of the molecular ordering process caused by the applied shear during their formation.