Influences of Thermal and Gustatory Characteristics on Sensory and Motor Aspects of Swallowing

Abstract

Two sets of experiments were conducted to examine the effects of two sensory modalities, temperature and taste, of foods on perceptual and motor aspects of swallowing in 20 young, healthy subjects (10 subjects for each experiment). A tasteless and odorless thickening agent was the basic testing material. The first experiment compared the swallowing of foods at four temperatures ranging from 5 degrees C to 50 degrees C. Food at 50 degrees C was more acceptable for swallowing than at 5 degrees C, 20 degrees C, or 35 degrees C. The suprahyoid muscles were less active during swallowing food at 50 degrees C compared with swallowing food at the other three temperatures. The second experiment compared foods with the five basic taste qualities (sweetness, saltiness, sourness, bitterness, and umami) with a tasteless food (dissolved in distilled water) to examine the influence of gustatory sensation. The sweet and tasteless foods were somewhat more acceptable for swallowing than the sour and bitter foods. However, none of the foods differentially altered the motor parameters of swallowing. Interactive influences of temperature and gustatory sensations of foods on swallowing are discussed.

Effect of a Bitter Bolus on Oral, Pharyngeal and Esophageal Transit of Healthy Subjects

“…The pleasant sweet taste induced the weakest autonomic nervous system response whereas the unpleasant bitter taste induced the strongest response (12) . Foods with sweet taste are more acceptable for swallowing than foods with bitter taste (10) . Taking into consideration these observations, we expected that the bitter taste bolus might cause different transit duration response than other bolus taste.…”

“…In normal subjects, the swallow has a sequence of events and timing which does not change in function of the bolus taste (10) . The central mechanisms of swallowing control cause the same response that is independent of bolus taste.…”

“…Ingestion of a bitter bolus might influence swallowing and alter the oral, pharyngeal and esophageal transit. However, there are results showing that a bitter taste bolus does not alter the durations of the oral, oropharyngeal and pharyngeal phases of swallowing of normal subjects, compared with other basic tastes (10) . In this investigation, we evaluated the effect of a tea of Peumus boldus, frequently used in popular medicine (13) , which has a bitter taste, on oral, pharyngeal and esophageal transit, compared with the swallow of a sweet bolus.…”

“…During swallowing, boluses stimulate sensory receptors of the oral, pharyngeal, laryngeal, and esophageal regions (10) . The stimulus of taste has influence on the coordination between breathing and swallowing, duration of oral preparation of the bolus and contraction of muscles in the submental region (9) .…”

“…Subjects with no perception of bitter taste are less resistant to venction-induced motion sickness and nausea, symptoms which are considered another way to avoid the ingestion of potentially harmful foods (2) . Sweet and tasteless foods are more acceptable for swallowing than bitter and sour foods (10) . A bitter taste is unpleasant for most subjects (8,12) , and the perception of this bolus taste is part of the defense system against inadvertent toxin ingestion (2) .…”