Roles of viscosity, applied load and surface wettability on the lubrication behaviour of model liquid/semi-solid foods: Measurements with a bespoke tribo-cell fixture and rotational rheometer

Abstract

Thin film sliding and friction phenomena of food bolus confined between tongue-palate surfaces during oral processing can be explored using tribological measurements. However, these measurements are still limited within the food industry due to the requirement of expensive commercial instruments which are not commonly used in the food industry. This work has designed and manufactured a modular “tribological cell” (tribo-cell) that can simulate lubricated soft-hard contact interfaces and can be mounted on a rotational rheometer to perform tribological measurements. The tribo-cell was validated by performing tribological measurements using a range of corn syrup solutions as model liquid foods. It was shown that the Stribeck curve describing the change in friction behaviour with entrainment speed or with the product of entrainment speed and liquid viscosity could be obtained. Since tribology deals with surface property, the cell was then used in the further studies to demonstrate the effects of applied normal load and surface wetting on the tribological response of lubricated hard-soft contact of the designed fixture. These parameters were shown to have a marked influence on in the boundary and mixed-lubrication regimes. The designed tribo-cell was also used to illustrate the impact of fat content on the lubrication properties of commercial liquid and semi-solid foods with different fat contents, thus, pointing out to the importance of tribology as a vital tool for product formulation designs in food and beverage industry.

Rheology for Safe Swallowing 3

“…Recently, a modified set-up of tribological measurement was used to study the Newtonian fluids (Fig. 76) 254) . Normal load as a function of entrainment speed from 0.1 to 1000 mm s −1 for Newtonian corn syrups (viscosity η = 0.01-3 Pas) was found constant ca.…”

“…77b. Therefore, Gamonpilas et al 254) stated that, for Newtonian liquids, the liquid viscosity is considered as a shift factor for the Stribeck curve, i.e., the higher the viscosity, the shifting is more toward the hydrodynamic lubrication regime. This finding is consistent with previously published works 248,252,253,255) .…”

“…Fig. 76 (a) A schematic drawing of tribological-cell (tribo-cell) and (b) its set-up on a controlled strain rheometer ARES-G2 (TA Instruments, USA) 254) .…”

“…Fig. 77 Tribological properties of Newtonian liquids (20-100 % corn syrups) with varying viscosity, plotted as a function of (a) entrainment speed, V and (b) the product between viscosity and entrainment speed, ηV with the applied normal load of 3 N. Different regions of the Stribeck curve, defined as Boundary-, Mixed-and Hydrodynamic-lubrication regimes are observed and indicated by the dashed lines 254) . Fig.…”

Investigation of lubricant viscosity and third-particle contribution to contact behavior in dry and lubricated three-body contact conditions

“…For low-viscosity fluids, only boundary lubrication regimes can be observed. As the viscosity of the fluid increases, both boundary and mixed lubrication regimes can be observed, indicating that the fluid generates sufficient hydrodynamic lift to partially separate the rough contact surfaces (Gamonpilas et al, 2022). Sun et al investigated the effects of lubricant viscosity on the vibration and temperature rise of silicon nitride full ceramic angular contact ball bearings under different axial loads and speeds.…”