Electromyographic texture characterization of hydrocolloid gels as model foods with varying mastication and swallowing difficulties

Eating difficulty of solid foods was analyzed using electromyography (EMG) of five hydrocolloid gels with varying textures. Eleven subjects ate gel samples under normal conditions and EMG activities of both sides of masseter (jaw-closing) and suprahyoid (jaw-opening) muscles were recorded during eating. Differences in EMG variables among samples were analyzed separately before and after the first swallow using repeated-measure statistics. The time before the first swallow was related to chewing effort and was estimated according to numbers of chewing actions, masseter muscle activities per chew and the sum of masseter muscle activities during chewing. EMG variables were also correlated with resistance to fracture, which was extracted as the first principal component from sensory evaluations of gel texture, but did not directly relate to any single parameter from mechanical tests or sensory evaluations. The time after the first swallow to the end of eating corresponded with the number of swallows, the EMG amplitude of suprahyoid muscles during chewing, the sum of masseter activity and suprahyoid muscle activity during the period after the first swallow. These EMG variables corresponded with sensory evaluations of adhesiveness but not with other single mechanical and sensory parameters or principal components. The present data suggest that at least two independent factors affect eating difficulty. Although differences among the five gels were predominantly reflected by chewing difficulty, these remained significant after the first swallow. (C) 2014 Elsevier Ltd. All rights reserved.