To evaluate food texture by measuring the response to compressing and also grinding by mastication movements, we recorded the electric discharge from the muscle temporalis and the movement of the jaw. These measurements were made by using electromyography (EMG) and mandibular kinesiography (MKG) simultaneously during mastication. Comparing the EMG and MKG charts, the masticatory movement could be divided into two time phases-the chopping phase time (
D1), and the grinding phase time (
D2). Masticatory movement was repeated until the foods were swallowed. These repeated movements were counted as a number of mastication cycles. Nineteen foods, widely varied in textural properties, were selected and used.
The total masticatory times and the number of mastication cycles varied among foods. During mastication,
D1 decreased and
D2 increased.
Nineteen foods were classified into three groups according to differences of
D1 and
D2 time rates.
D1 correlated significantly to the firmness value obtained by a texturometer, but
D2 did not. It was shown that
D2 can be used to provide a more complete evaluation of food texture by giving information concerning response to grinding.
Moreover, this method of using both
D1 and
D2 measurements can be applied to textures of foods such as boiled spinach or shredded cabbage which can not be determined by usual instruments because these foods can not be made into special shapes required for testing.
View full abstract