Abstract
To investigate the effects of thickening agents, which may reduce the risk of aspiration, on the swallowing threshold during food mastication, the physical properties of bolus immediately prior to swallowing during mastication of test food containing a thickening agent (xanthan gum) were measured in healthy ten adult participants (mean age 31 yrs). Two kinds of test food (test food C, boiled Koya-dofu as a control and test food X, boiled Koya-dofu containing 1% xanthan gum) were prepared. Each test food has a cubic shape (15×15×15mm). Physical properties of test food and the test food bolus collected from the oral cavity immediately prior to swallowing were measured by method of the texture profile analysis (double bite test). Texture parameters (hardness, adhesiveness, cohesiveness, gumminess) were obtained from the stress strain curve. The number of chewing strokes until swallowing during mastication of the X was significantly smaller than that during mastication of the C. Hardness, cohesiveness and gumminess of both the C and X boluses were significantly decreased during mastication. Adhesiveness of the X bolus was also significantly (p<0.05) decreased during mastication, but the adhesiveness of the C bolus was significantly (p<0.01) increased. Adhesiveness of the X bolus immediately prior to swallowing was significantly (p<0.001) higher than that of the C bolus. These results suggest that the decrease in adhesiveness of bolus may be a main factor in initiating the swallowing during mastication of solid food containing the thickening agent. [J Physiol Sci. 2006;56 Suppl:S189]