Submitted to: American Journal of Primatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2005
Publication Date: 5/1/2005
Citation: Williams, S., Wright, B., Truong, V., Daubert, C.R., Vinyard, C.J. 2005. Mechanical properties of foods used in experimental studies of primate masticatory function. American Journal of Primatology. 67:329-346. Interpretive Summary: Texture and mechanical properties of foods influence the behavior of the jaw muscles during mastication. However, very little effort has been made to quantify the relationship between the masticatory responses of the subject and the mechanical properties of the foods that are eaten. This study provides data on the stiffness and toughness of a broad range of foods including apple pulp, almond, carrot, raisin, dried apricot, apple skin, gummy bear, prune pit, and popcorn kernel which were used in the electromyographic analysis of jaw-muscle behavior in various mammals. The results can help researchers studying primate mastication select among potential foods with broadly similar mechanical properties. Moreover, they provide a framework for understanding how jaw-muscle activity varies with food mechanical properties, and interpreting patterns of dietary niche partitioning and evolution of the masticatory apparatus.
Technical Abstract: In vivo studies of jaw-muscle behavior have been integral factors in the development of our current understanding the primate masticatory apparatus. However, even though it has been shown that food textures and mechanical properties influence jaw- muscle activity during mastication, very little effort has been made to quantify the relationship between the elicited masticatory responses of the subject and the mechanical properties of foods they are consuming during these in vivo studies. Recent work on human mastication highlights the importance of two mechanical properties, toughness and elastic modulus (i.e., stiffness), on food breakdown during mastication. Here, we provide data on the toughness and elastic modulus for the majority of foods used in experimental studies of the non-human primate masticatory apparatus. Food toughness ranges from approximately 56.97 Jm-2 for apple pulp to 4355.45 Jm-2 for prune pit. The elastic modulus of the experimental foods ranges from 0.07 MPa for gummy bear to 346 MPa for popcorn kernels. These data can help researchers studying primate mastication select among several potential foods with broadly similar mechanical properties. Moreover, they provide a framework for understanding how jaw-muscle activity varies with food mechanical properties in these studies.