Besides nutrition, functionality, and mastication, swallowing is one of major attributes to be fine-tuned in senior-friendly foods due to the risk of aspiration. Triobology is an emerging technique to mimic oral processing between tongue-palate and/or tongue-food by monitoring friction behavior of food fluids between ball and pins. In this study, extended stribeck curves were established with yogurt products varying in viscosity (77-1025 mPas). In the extended stribeck curve, a shift from static to kinetic state of motion (i.e., breakaway point) was detected in response to elastic deformation of the system. The friction coefficient and sliding velocity at the breakaway point displayed a negative correlation (R2= 0.998 and 0.997, respectively) with viscosity (at 50 s-1 shear rate). This relationship was also true for the first highest peak in the extended stribeck curve, but lesser extent exhibited (R2= 0.976 and 0.942, respectively). Yogurt samples varying in non-fat milk solids (8.5% 10%, 12%, w/v) were subjected to sensory evaluation. Results were assessed by rolling correlation with extended stribeck curves, and rheological parameters including viscosity (at 50 s-1 shear rate) , G’ and G” (at 1 and 10 rad/s). The results showed that viscosity, G’ and G” values were associated with a low range of sliding speed (~4.94E-06 mm/s) including breakaway point, which correlated with cohesiveness in the mouth, coated and residual feelings after swallow. Apparent viscosity and stickiness were associated with the latter stage of hydrodynamic friction (0.63-1.0 mm/s), while smoothness when swallowing was highly associated with the early stage of hydrodynamic friction (0.013-0.199 mm/s), which finally impacted on the textural acceptance. Overall results indicate that correlation amongst rheological and tribological results and sensory assessment is an effective tool to predict specific food structure and formulation ideal for target consumers.

Tribological approach using extended stribeck curves to understand oral processing for the elderly

ACS Fall 2020 Virtual Meeting

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