Abstract: Food oral processing is a highly complicated process involving mastication, size reduction, saliva secretion, and bolus formation. It is not only a process of food oral manipulation, but also a process of sensory perception. During oral processing, relative surface movements occur between food particles and between food particles and oral surfaces. Therefore, how to accurately describe the physical principle of food oral processing is beyond the scope of traditional rheology, and many sensory properties (smoothness, fattiness, oiliness and aftertaste) cannot be assessed simply by rheological measurements. In recent years, oral soft friction technology has emerged as a feasible approach for linking food oral processing to sensory perception. This article aims to describe the fundamental principle of tribology and the ABC of oral soft friction technology with focuses on the biological basis and measurement methods for oral soft friction theory. The latest advances in the application of oral soft friction technology in food design and sensory evaluation are highlighted.

Key words: oral soft tribology; tribology; sensory perception; food texture; food oral processing