Abstract
To study the influence of adhesiveness of ingested food on masticatory behavior in humans, electromyographic activity (EMG) was recorded from the masseter muscle (M) and the mylohyoid muscle (MH) using surface electrodes in eleven adult subjects. Rice starch paste (RP) concentrations of 5, 10, 15, 20wt% was used for mastication. The chewing time and the MH activities until deglutition were measured. The texture of RP was measured according to the texture profile analysis. During mastication of RP, continual MH activities, including tongue muscle activities, were observed in all subjects; but M activities were not observed except for 20% RP mastication in four subjects. This finding suggests that mastication of RP may be mainly performed by the tongue. As RP concentrations decreased, both the chewing time and the amount of MH activities significantly decreased. When the oral cavity was wetted by water or saliva, the chewing time significantly decreased. As RP concentration decreased, the adhesiveness and the hardness of RP decreased. When the surface of the plunger was wetted by water, the adhesiveness of RP significantly decreased, but the hardness did not. These finding suggest that the adhesiveness of RP may affect the chewing time until deglutition.
