Effects of texture properties of semi-solid food on the sensory test for pharyngeal swallowing effort in the older adults

BACKGROUND: Increasing viscosity can reduce the risk of aspiration into the airway, but excessively thickened food may require more force and effort. We assumed that semi-solid foods with similar viscosities will behave differently in the oropharynx and there might exist the possibility that properties other than viscosity may have clinical relevance. This study aimed to find out the texture of semi-solid foods that affects the effort of pharyngeal swallow in the older adults. METHODS: Nine kinds of semi-solid foods not requiring mastication were selected for texture profile analysis (TPA), and included whipped cream, mayonnaise, soft tofu, mango pudding, boiled mashed pumpkin, boiled mashed potatoes, boiled mashed sweet potatoes, red bean paste, and peanut butter. Hardness, adhesiveness and cohesiveness of each food were measured three times by using the rheometer. A blinded sensory test using a 9-point hedonic scale was also conducted in eighteen older adults people to investigate how much effort was required to swallow food, and how much of the food remained in the pharynx after swallowing. The correlation between texture and sensory outcome was statistically analyzed. RESULTS: Foods that belonged to the same viscosity category showed different texture values, and the participants also rated different scores respectively. Only adhesiveness among three properties was significantly correlated with the sensory test. (r = 0.882, p = 0.002 for difficult to swallow, r = 0.879, p = 0.002 for sense of residue). CONCLUSIONS: Adhesiveness was the most important property of the semi-solid foods, requiring most efforts in pharyngeal swallow in the older adults. If we select and provide food having low adhesiveness value in the same viscosity category, there might be the possibility to make it easier to swallow in older adults. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-020-01890-4.