A novel plate probe design for in vitro oral lubrication study of particle-containing food systems

The tribological interaction between the tongue and hard palate during food oral processing plays a critical role in textural perception. However, replicating this dynamic process in vitro presents significant challenges due to constantly changing shear rates, contact pressures and contact areas. In this work, we proposed an alternative method for lubrication quantification by employing a novel plate probe featuring a grooved structure and a rough substrate as tribopair. Feasibility was assessed by examining the effects of food properties (e.g., lubricant viscosity, particle presence); operational parameters (e.g., velocity, normal load); and surface characteristics (e.g., roughness, hydrophobicity) on frictional behavior. This plate probe effectively reduce amplitude of friction curve and stabilize force response while completing Stribeck curve. Surface roughness and hydrophobicity modulating lubrication in a manner similar to ball-on-disc setups, increasing surface roughness and wettability reduced boundary friction coefficients, while hydrodynamic lubrication remains independent of surface properties. However, increasing normal load leading to higher boundary friction coefficients, likely due to asperity deformation and the resulting increase in real contact area. In terms of particle participation, plate probe ensures effective particle entrapment. Results confirm proposed methodology is capable for quantifying friction behavior in both aqueous and solid particle dispersion systems. • A new cylindrical plate probe was developed for oral tribology applications. • Impact of probe geometry on friction was tested, showing significant differences between conventional flat-plate and ball-on-disc setups. • Reliability confirmed using near-Newtonian lubricants under selected system variables. • New probe design enables effective entrapment of discrete silica particles.