Sensory Investigation of Toothpaste Foam Using Rheology and Dynamic Foam Analysis

Consumer acceptance of toothpaste formulations is heavily influenced by oral tactile sensations, particularly foaming behavior. While Home Use Tests (HUTs) provide definitive consumer insights, they are resource-intensive and time-consuming. This study establishes an accelerated laboratory methodology to predict consumer perception of toothpaste foaming using instrumental rheology and dynamic foam analysis (DFA). Fifteen custom made toothpaste formulations varying in surfactant systems, abrasives, and sensates were evaluated. Laboratory evaluation included foam generation via a customized blender-rheometer geometry to monitor the viscoelastic properties (tan δ) of a paste-water slurry, paste yield stress analysis, and structural profiling via DFA. Multivariable linear regression revealed that the initial foam loss factor (tan δ) correlates strongly with consumer panel ratings for both Foam Degree (R² = 0.7) and Foam Liking (R² = 0.6). Integrating paste yield stress (σ_y) into a multivariate model markedly enhanced the prediction (R² = 0.8). Alternative multivariable models using tan δ and initial DFA parameters-specifically bubble count and average bubble radius-similarly yielded highly accurate predictions of mouthfeel (R² = 0.8). The findings demonstrate that formulations with low paste yield stress and high foam visco-dominance (higher tan δ) facilitate bubble formation and produce rich, consumer-preferred "liquidish" textures. Alternative multivariable models using tan δ and DFA parameters were also presented. This dual rheological framework provides an instrumental proxy to screen and optimize toothpastes prior to panel studies.