Mechanisms of fracture in foods

Most foods have solid-like properties and therefore must be size reduced in the mouth before swallowing. In this paper we will examine the physics of the fracture processes involved in breaking different food types. These range widely from brittle fracture in dry cereal foods, nuts, and fresh vegetables, to the complex defibrillation and tensile failure in cooked meats. We will examine how the differences in fracture and failure processes correlate with our perception of quality in various food types. This allows deduction of an overall model for the mastication process and how consumers may develop preferences for particular foods. The real stresses and strains exerted in the mouth are difficult to identify in local, spacial detail. Recent work is beginning to define how mouth motion controls the fracture process, and the impact of saliva on the mechanism of swallowing.