MECHANICAL-PROPERTIES OF FOODS RESPONSIBLE FOR RESISTING FOOD BREAKDOWN IN THE HUMAN MOUTH

The fragmentation of foods (breakage function) was measured in five hu mans on 'bagged' single particles of 28 foods from three food groups. The change in the square root of the specific surface of the particles (the specific surface being the area of particle silhouettes, measure d by image analysis, divided by original particle volume) produced by one bite, averaged for all participants, was inversely linearly relate d to the square root of the toughness of the foods divided by the squa re root of their Young's moduli (r = -0.86; p < 0.00001). This relatio n is predicted by an analysis based on food fragmentation within a lim ited jaw displacement. Thus, resistance to jaw movement appears to pro vide sensory information on the deformation, fracture and fragmentatio n of foods. It is believed that this is the first time that a relation between the breakage of food particles by the teeth and their materia l properties has been found, and the finding has considerable implicat ions for human masticatory studies, for the analysis of dentition and diet in mammals and for texture studies in food science. (C) 1997 Else vier Science Ltd.