Fig 1.
Schematic diagram for measurement. (A) Schematic diagram for measurement of bolus Young’ modulus. (B) Schematic diagram for measurement of bolus volume.
Table 1.
Composition of artificial food bolus.
Fig 2.
Properties change of different ingredients with chewing. (A) Alterations of Young's modulus according to the mastication time. All sample foods indicate a drastic decrease of Young's modulus within 10 times, and turn to the moderate decrease phase. Red arrow in graph represents the mean swallowing time of research participants. (B) Alterations of volume according to the mastication time. All sample foods indicate a volume decrease during mastication. Red arrow in graph represents the mean swallowing time of research participants.
Fig 3.
Saliva viscosity and Weight ratio of saliva. (A) Saliva viscosity of research participants measured by viscometer. (B) Weight ratio of saliva contained in the obtained bolus soon before swallowing.
Fig 4.
Fabrication of artificial food bolus. (A) Young's modulus of alginate hydrogel. The value increases according to the sodium alginate concentration. (B) Viscosity of gelatin solution. The value increases according to the gelatin concentration. (C) Young's modulus of artificial food bolus. The value mainly reflects the Young's modulus of alginate hydrogel.
Fig 5.
Swallowing evaluation using artificial food bolus. (A) The prepared artificial bolus for swallowing evaluation. The artificial food bolus was molded with the prescribed volume. (B) Laryngeal elevation (red arrow) time was measured as swallowing time. (C) The swallowing time of artificial bolus with different volume. The time increases linearly until the volume of 400 mm3, and then largely increases more than this volume (P **<0.01). (D) The swallowing time of artificial food bolus with different Young's modulus. The time increases linearly until the modulus below 110 kPa. Participants are unable to swallow the artificial bolus of 200 kPa without mastication. (E) The swallowing time of artificial food bolus (100–400 mm3) with different Young's modulus. The swallowing time of artificial bolus below 23.8 kPa indicates the significantly rapid swallowing.