The relationship between chewing activity and food bolus properties obtained from different meat textures (original) (raw)

During chewing, a meat sample is mashed under compression and shear bite forces whilst saliva is incorporated. The resulting mixture is shaped into a cohesive bolus by agglomeration of small particles to trigger a swallow. This study aims to investigate the relationship between meat structure before chewing and texture after various chewing durations, according to the subject's chewing behavior. Twenty-five young adults participated. Electromyography activity (EMG) was recorded from surface electrodes on the elevator muscles during mastication of cold beef (5 g). Two different meat textures were obtained by varying aging and cooking temperature. Subjects were asked to chew and then to spit out the bolus either after a constant chewing duration (7 s) or when the bolus was ready to be swallowed. Boluses were then weighed to determine saliva incorporation. Cutting tests were applied to measure maximum shear force and to assess bolus structure homogeneity. From EMG recordings, temporal and amplitude parameters were analyzed. The mechanical shear force was maximal for meat before chewing and decreased for the bolus with the lengthening of the chewing duration. Significant texture differences were found for samples before chewing and for two types of bolus but differences were larger for the bolus after 7 s chewing than for the bolus when ready to be swallowed. The amount of saliva incorporated into the bolus increased with both chewing muscular activity and chewing duration. Finally, the more chewing cycles before swallowing, the more comminuted the meat bolus (lower shear force) and the more saliva was incorporated in it. These results fit with one of the major roles of the saliva, that is, to provide cohesion between particles [Nature 391 (1998) 329] and with the intra-oral management of meat during chewing as analyzed by videofluorography [Arch. Oral Biol. 47 (2002) 267].