Soft lubrication characteristics of microparticulated whey proteins used as fat replacers in dairy systems

• Published in: Journal of food engineering 2019-03, Vol.245, p.157-165
• Main Authors: Olivares, M.L., Shahrivar, K., de Vicente, J.
• Format: Article
• Language: English
• Subjects: Elastohydrodynamic lubrication; Food colloids; Soft lubrication; Tribology
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2018.10.015

In this work the fat mimicking mechanism of microparticulated whey proteins (MWP) in milk-based systems was studied using rheological and tribological techniques. Flow curves and friction measurements in a soft contact of skim milk-MPW dispersions (SM-MPW) and skim milk-dairy fat emulsions (SM-DF) at different concentrations (3, 6, 9, 12, 15, 18 and 20% w/w) and temperatures (25 °C and 37 °C) were carried out and compared. Friction coefficient curves of SM-MPW dispersions as a function of the product of entrainment speed and viscosity collapsed into a single master curve in the mixed and elastohydrodynamic (EHL) regimes when the high shear viscosity values as obtained through Carreau-Yasuda model were used. This suggests that the dispersions as a whole entrained in the contact. However, in the case of SM-DF emulsions, a very good collapse is obtained if only SM is assumed to pass through the contact. Simulations of friction coefficient within the EHL region showed a reasonably good continuity of the experimental data for SM-MPW dispersions and SM-DF emulsions. Finally, it was observed that friction levels attained with MPW proteins and DF at typical speeds involved in oral processing were comparable, hence demonstrating the capability of SM-MPW proteins dispersions to imitate DF in milk-based systems from a lubrication point of view. •Fat mimicking mechanism of microparticulated whey (MPW) proteins in milk-based systems studied by rheology and tribology.•Comparison between Skim milk-MPW dispersions and Skim milk-dairy fat (DF) emulsions.•Stribeck curves and simulations help to infer about the viscosity contribution to the friction coefficient.•Typical friction coefficient values attained by MPW proteins and DF in oral environment conditions.