Effects of texture of food on chewing patterns in the human subject.

To elucidate the effects of food character on chewing patterns in humans, the electromyographic activity (EMG) of the chewing muscles and also the jaw movements were recorded in twenty-nine young subjects during ordinary chewing of five different foods. The results obtained were as follows. (a) The harder food materials showed a higher amplitude of the masseter EMG than the softer ones. (b) Concerning the number of chewing strokes and the elapse of time until the last swallowing action, subjects could be divided into two groups. (i) In the first major group, the number of chewing strokes and chewing time until the last swallowing action increased following increase of hardness of the food. This suggests that chewing force and chewing movements may be strongly influenced by the texture of food, especially its hardness. Further, the degree of pulverization of eating materials appears to be the major factor in controlling the swallowing action. (ii) In the second minor group, the chewing strokes and the chewing time were less influenced by the hardness of food. Here, a certain number of chewing strokes could be stimulating the swallowing centre in the brain and so induce swallowing, regardless of the degree of pulverization of the food.