Impact of proprioception and tactile sensations in the mouth on the perceived thickness of semi-solid foods

Although sensory tests are already a common tool in the food industry and research, the way in which humans perceive the mouthfeel of liquid and semi-solid foods is still far from being completely understood. In contrast to mouthfeel, most olfactory and gustatory sensations are attributed to specialized sensor types which stimulate the sensory cells directly. This might be the reason why their sensation can often be modeled by unidimensional relations. Sensory attributes such as “consistency” and especially “creaminess” are, however, multidimensional in nature, which might be ascribed to the fact that more than one sensory system is included in the process of thickness evaluation. This study investigated the impact of two sensory systems on the perception of thickness of semi-solid foods, namely proprioception of the tongue and the tactile senses. The anesthetic lidocaine was used to inhibit the tactile mechanoreceptors, leaving the proprioception unaltered. Therefore, the separate effects of these two systems on the thickness could be observed, using vanilla custard as a model food. This study suggests that the mechanosensors are almost exclusively responsible for the sensation of mouthfeel and proprioception plays a negligible role.