Mouthful Size Effects on Mastication Effort of Various Hydrocolloid Gels Used as Food Models

This study aimed to quantify effects of food mouthful size on eating effort while masticating solid foods represented by five hydrocolloid gels varying in texture by means of electromyography (EMG). Eleven subjects ate 3 (S) and 6 (L) mL mouthfuls of five gel samples in their normal way without any designated conditions. EMG activities from both masseter muscles, as jaw-closing muscles, and the suprahyoid muscles, as the jaw-opening muscles, were recorded during free eating. Differences in EMG variables were analyzed separately before the first swallow and during the entire oral processing until the last swallow. When food size was halved from L to S, entire time of oral processing, the number of chews, and the number of swallows were approximately 0.7 times more than those for L gels. The sum of muscle activities was determined by both the jaw-closing and jaw-opening muscles, and the relative values for S gels were about 0.8 of the L gels. EMG variables per chewing motion were not significantly different between S and L gels. Those observations were found to be similar for the five different gel types. These results suggest that the mastication effort can be estimated quantitatively for hydrogels with wide range of texture if a small enough mouthful size is consumed. The mastication effort for L gels was 1.4 times greater than that of S gels; however, it was never greater than 2 times the S gels.