Physical Properties, Ease of Swallowing and Behavior of the Bolus through the Pharynx of a Mixed Gel-Sol Food Based on Grated Yam

Abstract

This study investigated the coherence of minced food with grated yam sol. Sol samples were prepared using grated yam sol and mixed gel-sol samples were prepared by 4-mm cubic gels (rupture stress of 1.43 (±0.14)×10⁴N/m²) with grated yam sol. The present study used powdered yam to add viscosity to liquids, and sol samples with three different hardnesses were prepared (resembling the hardness of salad oil, plain yogurt and mayonnaise). Furthermore, mixed gel-sol samples were prepared with sol samples with three different hardnesses and with 4-mm cubic gels accounting for 50% by volume of the sample. Physical properties, sensory evaluation and videofluorographic examination of swallowing of these samples were investigated. The oral sensation results obtained by sensory evaluation were found to be greatly affected by the physical properties of the sol part of the mixed gel-sol samples. The results of the videofluorographic examination of swallowing demonstrated that, in the case of sol samples, the harder the sample, the slower the transit speed of the sample from the mid pharynx to the hypo-pharynx. Also, in the case of both the sol samples and the mixed gel-sol samples, the higher the stickiness in oral sensation and the adhesiveness in textural properties, the longer it tended to take from the onset of hyoid bone movement to when the sample reached the piriform sinus. With the mixed gel-sol sample whose sol part had a hardness resembling that of salad oil, two subjects tested were found to have some pharyngeal residue of the gel after swallowing. On the other hand, with the mixed gel-sol sample whose sol part had a hardness resembling that of mayonnaise, none of the subjects tested were found to have any pharyngeal residue of the gel after swallowing. These findings indicated that, in the case of using grated yam to add coherence to minced food of about 4 mm, preparing the sol part to have a hardness resembling that of plain yogurt and mayonnaise reduces the possibility of the minced food forming pharyngeal residue.