A Pilot Study on Ultrasound Elastography for Evaluation of Mechanical Characteristics and Oral Strategy of Gels

Abstract

Ultrasound elastography as a simple and noninvasive method was used to evaluating the texture of gels. Three gellan gum gels with different mechanical characteristics and sonagel which has the similar elastic modulus to that of the human tongue were used. The combination of sonagel and gellan gels was lightly compressed and released cyclically with an ultrasound probe with 1-2 Hz. We obtained the strain for each cycle, and analyzed the results using the maximum values of strains. We found that the strain ratio between the gellan gel and the sonagel increased with the decrease of gellan gel fracture force. And also the oral strategy changes from teeth mastication to tongue-palate compression with the increase in the strain ratio. Strain obtained by ultrasound elastography is revealed as an important parameter that indicates the mechanical characteristics and even oral strategy of gels. PRACTICAL APPLICATIONSInstrumental methods are often used for texture characterization. Normally, probes are made of metal or plastic materials that are much stiffer than foods and completely dissimilar to the tongue. As a noninvasive method, ultrasound tissue elasticity imaging has provided novel diagnostic information regarding tissue diseases. We suggest that ultrasound elastography can be used for food texture evaluation in the present study. It is possible to observe deformation behavior as the tongue-palate compression if the material whose mechanical characteristics is similar to the human tongue was used as an artificial tongue in the method.

Relationships Between Mechanical Properties Obtained from Compression Test and Electromyography Variables During Natural Oral Processing of Gellan Gum Gels

“…; Gao et al . ) (Table ). Food color (0.2%, SAN GREEN GC‐EM, San‐Ei Gen F.F.I., Inc.) was added (Ishihara et al .…”

“…The five gellan gels were categorized into two groups: equivalent fracture strain group (F1, F2 and F3) as shown in the second column of Table as used in our previous study (Gao et al . ) and equivalent fracture load group (S2, F2 and E2) as shown in the third column of Table .…”

“…In our previous study, subjects were asked which oral method was used, tongue‐only compression or mastication, while eating a piece of gel (Gao et al . ). Sensory evaluation was ambiguous in some cases and some subjects answered “not sure” for soft gels.…”

“…Three of the five (F1, F2 and F3) having a similar fracture strain (approximately 60%) but different fracture loads (F1 < F2 < F3) as reported previously (Gao et al . ) were used to investigate the effects of fracture load. Two gels having higher (E2) and lower (S2) fracture strains than the three gels having a similar fracture load as F2 (approximately 14 N) were added to investigate the effects of fracture strain.…”

“…In addition to the apparent modulus, fracture load and strain measured in our previous study (Gao et al . ), we also evaluated the true fracture stress. We discuss the relationship between mechanical characteristics and natural eating behavior measured by EMG.…”