Sensory Investigation of Toothpaste Particle Perception in the Mouth

In this work, we investigated the mouthfeel attributes of toothpaste, specifically particle perception in the mouth that is the root cause of the "grittiness" feeling. Employing panel evaluation, rheology, tribology, and surface characterization techniques, we explored the correlations between particle presence, size, and homogeneity ratings and the rheological and tribological properties of toothpastes. Panel assessments revealed that particle size and homogeneity perception positively influenced particle presence perception. Rheological analyses identified that yield stress and flow index of the pastes obtained by the Herschel-Bulkley model, as well as a high shear viscosity of the diluted (1:2) slurries of these pastes (calculated from power-law at 3000/s) can be used to predict particle perception ratings. Moreover, the coefficient of friction and surface roughness parameters from tribological and surface characterizations are also statistically significant parameters in particle perception in the mouth. We then presented predictive models involving these parameters with high accuracy (R² > 0.88). These findings provide valuable insights into the physicochemical drivers of toothpaste mouthfeel and contribute to predicting and optimizing consumer experience in product development.