Effect of Maximal Voluntary Tongue Pressure and Mechanical Properties of Gels on Tongue Pressure Production when Squeezing Gels

Soft foods like gels, which are often used as care foods, are usually processed with the tongue (i.e, squeezing) by elderly consumers with chewing difficulty. However, little is known about squeezing, especially the relationship between individual tongue function and squeezing behavior, such as average tongue pressure per squeezing cycle (ATPS) and the number of squeezes until swallowing. The aim of this study was to evaluate squeezing behavior from both the aspects of individual tongue function and the mechanical properties of gels. Fourteen healthy young men were recruited. A 0.1-mm-thick pressure sensor sheet with five measuring points was used to measure tongue pressure when squeezing 5 ml of gels with four different fracture force and strain. Maximal amplitude, duration and area of tongue pressure during squeezing, ATPS, the number of squeezes until swallowing were evaluated. The maximal voluntary tongue pressure (MVTP) was also evaluated. Differences of the tongue pressure when squeezing four gels were statistically analyzed. The relationship between MVTP, ATPS and the number of squeezes were also analyzed. All evaluation items concerning squeezing gels increased as the fracture force increased. MVTP was positively correlated with ATPS and negatively correlated with the number of squeezes. Furthermore, MVTP and the fracture properties of gels were associated with ATPS and the number of squeezes. These results suggest that individual tongue function and the mechanical properties of gels have an influence on the squeezing behavior, and MVTP has potential as a biomarker for selecting care foods that can be safely ingested.