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

Abstract

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.

Salivation Correlates with Masseter Muscle Activity and Partially Depends on the Physical Characteristics and Volume of Food Consumed at One Time

“…This suggested that the volume of gel consumed at one time affects salivation only when the volume is sufficiently small; a volume over a certain threshold does not stimulate additional salivation. A previous study showed that the volume of food consumed at one time affects the number of chews and duration of mastication but not the masseter muscle activity per chew (Kohyama et al, 2014(Kohyama et al, , 2016a. Unfortunately, the number of chews and the duration of mastication could not be evaluated in this study because we set the duration of mastication to be 30 s. In fact, EMG activities in 30 s did not differ significantly between mastication of 1 piece and 3 pieces of each gel type, suggesting that the increase in salivation for mastication of ≥ 2 pieces compared with 1 piece was hardly caused by the difference in EMG activity.…”

“…The desired volume of each solution was obtained by adding deionized water. Each solution was then poured into glass ring molds (20-mm diameter; 10-mm height; 3.14-mL volume) (Ishihara et al, 2013(Ishihara et al, , 2014Kohyama et al, 2014Kohyama et al, , 2016bKohyama et al, , 2017. The samples in molds were heated at 85 ℃ for 30 min and then refrigerated at 4 ℃ for at least 1 h. Gels were allowed to stand at 23 ℃ for 1-3 h before using for experiments.…”

“…Salivation measurement The subjects washed their mouths with activated carbon-filtered water (Water purifier TK-AS44, Panasonic Corporation, Osaka, Japan) approximately 2 min before each test. Subjects were instructed to take sample gels placed on a plastic spoon or equivalent volumes of water in a cup at one time, masticate for 30 s, which was sufficiently long considering the duration of mastication for 3 g of hydrocolloid gels (Kohyama et al, 2014;2016a), and expectorate all of the oral contents, including the saliva secreted during mastication, into the same cup. Immediately afterwards, saliva was collected into the same cup for 60 s.…”