*2.6. Flow Behavior and Tribological Measurements*

Mayonnaise rheological measurements were performed at 25 ◦C by a controlled stress–strain rheometer (MCR 302, Anton Paar, Graz, Austria) connected to a circulating water bath for temperature control. The flow behavior of the samples was evaluated by using a parallel plate configuration (50 mm) and a gap distance of 1 mm, and excess sample protruding from the edge of the sensor was carefully trimmed off with a thin blade. Flow curves were measured by recording viscosity values shearing the samples at logarithmic increasing shear rates from 3 to 300 s<sup>−</sup>1. Flow curves were built for all of the tested samples and fitted to the Herschel–Bulkley model by using Excel's solver software to obtain the yield stress (τ0), consistency index (k), and flow index (*n*). The friction and lubricant properties of model-like mayonnaise samples were evaluated using a tribology apparatus (Anton Paar, Graz, Austria) fitted to the rheometer. The measuring cell consisted of a ball-on-three-plates geometry consisting of a rotating glass ball and three stationary cylindrical polydimethylsiloxane (PDMS) pins fixed to the sample holder. The ball measured 12.7 mm in diameter and the pins measured 6 mm in diameter and height. The friction and lubricating properties of mayonnaise samples in between two surfaces were recorded at 30 ◦C with a normal force (FN) of 1 N. The Stribeck curves for each sample were shaped by plotting the friction factor (−) versus the sliding velocity (Vs).
