Semisolid Food Tribology

Abstract

Tribology, or friction, lubrication, and wear behaviors between sliding countersurfaces, is a subset of rheology. The current consensus is that tribological behaviors of foods may be linked to friction-related food textural attributes. Because friction-related behaviors cannot be determined by traditional rheometry, tribological data may better correlate to friction-related textural attributes than rheological data (Malone ME, Appelqvist IAM, Norton IT, Food Hydrocoll 17:763–773, 2003a; Prakash S, Tan DDY, Chen J, Food Res Int 54:1627–1635, 2013). Indeed, semisolid foods are palated during consumption, and the motions of the oral surfaces during palating involve one surface sliding against another, generating friction-related sensations. However, textural attributes involve complex, temporal sensations (Prakash S, Tan DDY, Chen J Food Res Int 54:1627–1635, 2013; Hutchings JB, Lillford PJ, J Texture Stud 19:103–115, 1988; Lenfant F, Loret C, Pineau N, Hartmann C, Martin N, Appetite 52:659–667, 2009), making universal relationships between semisolid food tribological behaviors and sensory attributes difficult to determine. Furthermore, it can also be challenging to isolate the contribution of a single food component to semisolid food friction behaviors, particularly if the friction behaviors of the food change under oral conditions (e.g. the presence of saliva). While several basic relationships have been established, such as a direct relationship between sensory astringency from tannins and friction coefficient in the presence of saliva, much work is needed to fully understand the universal relationships among semisolid food composition and structure, instrumental friction measurements, and textural attributes.