Sugar or milk: Tribological study on the sensation of coffee beverages

Coffee is a beverage with a long history of global popularity. In this study, the physicochemical characteristics, rheological and tribological properties, and oral tribological simulations of six different coffee formulations were investigated, and 12 characteristic attributes were quantitatively evaluated. The results showed that the coefficient of friction (COF) was directly related to the important sensory characteristics of coffee beverages and that changes in both sugar and milk content manifest as changes in the COF, which affect the stress and strain distribution at the tongue-palate interface. Our study demonstrated that tribology can, in conjunction with the characterization of other physicochemical properties, be used as a tool for the fast and easy prediction of important taste parameters of food.