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Tongue pressure measurement in food science
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ScienceDirect Tongue pressure measurement in food science Takahiro Funami Recently published two articles relating to tongue pressure measurement during food oral processing and its usefulness for food texture study are highlighted. Tongue pressure measurement must be a new approach for texture design of food products particularly for specified consumer group with reduced capability of eating. In this article, a novel sensor for the measurement is introduced with emphasizing its advantages which enable natural and habitual eating behavior. Potential usage of the measurement to know the dynamics of food oral processing and to visualize the interaction between a food and the tongue are also indicated. Tongue pressure measurement can contribute to the progress of food texture study on both academic and industrial sides. Address San-Ei Gen F.F.I., Inc., 1-1-11, Sanwa-cho, Toyonaka, Osaka 561-8588, Japan Corresponding author: Funami, Takahiro ([email protected])
Current Opinion in Food Science 2016, 9:29–33 This review comes from a themed issue on Sensory Science and Consumer Perception Edited by Susana Fiszman
http://dx.doi.org/10.1016/j.cofs.2016.04.003 2214-7993/# 2016 Elsevier Ltd. All rights reserved.
Introduction Food texture analysis on human in vivo measurements is now popular in the food science field. Electromyography [1–4], biting force measurement [5–9], palatal pressure measurement [10,11,12], ultrasonic or ultrasound method [13,14], and videofluorography [15–17] are representative and provide us with a lot of insights into food oral management in human. The topic dealt in this article is tongue pressure measurement, and two related articles reported recently by the research team of Osaka University and Niigata University [18,19] are focused. They have been successful in mapping tongue pressure during oral processing using a novel device developed by the research team [20] mainly for clinical purpose. On the basis of the success, they have been trying to visualize the interaction between a food and the tongue during oral processing in human. Since the tongue plays a crucial role throughout food oral processing, which initiates from cognition, followed by size reduction (mastication or www.sciencedirect.com
squeezing), bolus formation, bolus transportation, and swallowing [21], it is reasonable from physiological point of view to link tongue movement with food texture. As a series of their trials, in these two articles, effects of food texture on tongue movement were investigated, and consistency [18] and rheological nature (i.e. elastic or plastic) [19] were selected as a dominating attribute of food texture. The idea of the research team to apply the device to food science is breakthrough.
Apparatus for tongue pressure measurement and its advantages The devise is a T-shaped sensor sheet with five measuring channels (presented as Ch. 1-5) attached to Swallow Scan system (Figure 1), enabling real-time monitoring of tongue pressure based on an electrical transducer mechanism (resistance to electrical current). The devise was originally established to architect the design of palatal plate particularly for tongue cancer patients. Measurement of the contact pressure between the tongue and the hard palate is necessary for customizing of palatal plate because the intensity and the pattern of the contact can change by the shape of the tongue after surgery. There are many technical advantages in the devise which support the idea of the research team. It is only 0.1 mm in thickness with different sizes and mechanical flexibility for easy adaptation to oral shape and does not change the oral physiology nor interfere with the occlusion. Also, the sensor sheet does not cover the overall area of the hard palate and thus does not interfere the perception of taste, aroma, or texture. It does not prevent natural and habitual eating behavior in human, and this must be no doubt the greatest benefit for food texture study. Manometer, in which a small balloon type probe is normally inserted into the oral cavity [22], may not cause too much discomfort to subjects but does not necessarily ensure natural eating. In addition, the devise is wearable and portable, and experiments can be carried out even on chair-side or bed-side. So far, over 20 articles have been published on this system, covering a wide range of research field from clinical, including diagnostic, treatment, and rehabilitation for the elderlies [23], tongue cancer patients, and stroke patients [24], to food texture study and providing the system with scientific validation.
Link of tongue pressure measurement to food texture Most reports on tongue pressure measurement deal with only swallowing but not so frequently with a whole series of food oral processing. Using this system, temporal and spatial distribution pattern of tongue pressure during oral processing is elucidated, and thus human eating behavior Current Opinion in Food Science 2016, 9:29–33
30 Sensory Science and Consumer Perception
Figure 1
(a)
(b)
Ch. 1
Ch. 2
Ch. 3 Ch. 4
Ch. 5
Current Opinion in Food Science
Swallow scan system (a) and location of measuring channels (b).
(or food eaten behavior) can be visualized using tongue movement as a benchmark. Rheological nature of food samples does not basically cause difference in temporal pattern of tongue pressure during squeezing, presenting first onset at the mid-median part (Ch. 2), followed by the anterior-median (Ch. 1) and the posterior-median (Ch. 3) parts and then by the circumferential parts (Chs. 4 and 5) regardless of rheological nature (Figure 2). However, some differences are found between elastic and plastic (i.e. deformable) food samples in offset, and as a result, duration of squeezing for plastic food sample tends to become shorter than that for elastic food sample when consistency is low, whereas vice versa when consistency is high. Also, spatial distribution pattern of tongue pressure during squeezing is different between elastic and plastic food samples; the maximum amplitude at the anteriormedian and mid-median parts are larger than that at the circumferential parts for elastic food sample, whereas no significant difference between channels for plastic food sample (Figure 3). These findings present difference in tongue movement during size reduction caused by food texture and also give us a hint on suitable food texture to specified consumer group with tongue-related digestion disorder.
For product development There must be an intention of the research team to utilize this system for food product development for the elderlies. Usage of polysaccharide gels as a model food is an implication because gel is a dominant food matrix for clinical foods particularly for dysphagic patients as seen in pudding and jellies [25,26]. Decreased capability of generating tongue pressure has implication to eating and swallowing behaviors for the elderlies, and food texture design based on tongue pressure is valid in Current Opinion in Food Science 2016, 9:29–33
this regard. The author believes that concept of ‘comfortable to the tongue’ should lead to innovation of food product development for the elderlies. It is possible to synchronize tongue pressure measurement with other in vivo measurements, and when focusing on swallowing, usage of a bend sensor which monitors the laryngeal movement [27] should be beneficial. Actually, in combination with bend sensor placed on the frontal neck (Figure 4), the coordination between laryngeal movement and hyoid motion during swallowing was elucidated, and the sequential order of tongue pressure and hyoid movement was displayed successfully [28]. In place of bend sensor, manometric catheter is applicable to see the oropharyngeal pressure flow dynamics during swallowing [29]. In addition, bodying sensation of beverages can be assessed by changes in both duration and the activity of the larynx required for one swallowing cycle using bend sensor [30].
For future study Discussion of tongue pressure measurement could be further expanded to cover some important aspects of food oral processing, such as dynamics of swallowing behavior, eating capability assessment, and artificial tongue etc. Tongue movement is basic to understanding the swallowing process, and tongue pressure measurement not only visualizes tongue movement but also clarifies different functions by tongue anatomy [31]. Tongue pressure relates to eating and swallowing capabilities of the elderlies [32,33], and its measurement can provide guidance of food choice for them. Usage of artificial tongue should be an idea for mechanical simulation of palatal reduction (i.e. size reduction by tongue-palate compression) [34,35], and tongue pressure measurement can help fabrication and selection of artificial tongue. www.sciencedirect.com
Tongue pressure Funami 31
Figure 2
Ch. 1 Ch. 2 S1
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
S2
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
S3
Ch. 3 * Ch. 4 Ch. 5 Ch. 1 Ch. 2
G1
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
G2
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
G3
Ch. 3
*
*
Ch. 4 Ch. 5 –0.4
–0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4 (s)
Onset
Peak time
Offset Current Opinion in Food Science
Time sequences of tongue pressure at each channel during the initial squeeze. The time ‘0’ was set as the onset of Ch. 1. *p < 0.05 (Kruskal– Wallis test and post hoc test with Bonferroni correction). S1-3 presents rheologically plastic food samples with increased consistency in order, whereas G1-3 presents rheologically elastic food samples with increased consistency in order. When the number is the same, consistency of food sample is equivalent between elastic and plastic food samples.
Food texture is a complex attribute and thus sometimes difficult to comprehend its whole entity. On the other hand, foods without complexity (in terms of appearance, flavor, texture etc.) are boring and not very pleasant for all www.sciencedirect.com
people. To understand such complexity of food texture, collaboration between oral physiology and food science should be strengthened more. For activation and enhancement of such an inter-disciplinal research activity, Current Opinion in Food Science 2016, 9:29–33
32 Sensory Science and Consumer Perception
Figure 3
(kPa) 45
*
40
S1
S2
S3
G1
G2
G3
*
*
* *
35 30
*
25 20 15 10 5 0 Ch. 1
Ch. 2
Ch. 3
Ch. 4
Ch. 5
Maximum amplitude
Instrumental test Current Opinion in Food Science
The maximum amplitude of tongue pressure at each channel during the initial squeeze. *p < 0.05 (one-way ANOVA test and Tukey’s post hoc test). See the footnote in Figure 2 for the sample denomination.
tongue pressure measurement should constitute a core part in the future. From these aspects, contribution of the measurement to the progress of food texture study can be highly expected. Figure 4
Conclusions On the basis of the temporal and special distribution of tongue pressure measured, biomechanics from oral to pharyngeal phase can be evaluated, interactions between human and a food can be visualized, and influences of food texture on the biomechanics can be evaluated. Thus, tongue pressure measurement links well oral physiology to food science and helps develop food products for the elderlies or dysphagic patients required in this aged society. Food scientists thus should study the validity of tongue pressure measurement and should utilize it more for texture design of food products to increase quality of life for these people. The author wishes that this article should lead to the progress of food science particularly food texture study.
References and recommended reading Papers of particular interest, published within the period of review, have been highlighted as: of special interest of outstanding interest
Current Opinion in Food Science
Frontal image of a subject with sensor sheet and bend sensor. Current Opinion in Food Science 2016, 9:29–33
1.
Kohyama K, Nakayama Y, Watanabe H, Sasaki T: Electromyography of eating apples: influence of cooking, cutting, and peeling. J Food Sci 2015, 70:S257-S261.
2.
Kohyama K, Ohtsubo K, Toyoshima H, Shiozawa K: Electromyographic study on cooked rice with different amylose contents. J Texture Stud 1998, 29:101-113.
3.
Kohyama K, Sawada H, Nonaka M, Kobori C, Hayakawa F, Sasaki T: Textural evaluation of rice cake by chewing and swallowing measurements on human subjects. Biosci Biotechnol Biochem 2007, 71:358-365.
4.
Kohyama K, Yamaguchi M, Kobori C, Nakayama Y, Hayakawa F, Sasaki T: Mastication effort estimated by electromyography for cooked rice of differing water content. Biosci Biotechnol Biochem 2005, 69:1669-1676. www.sciencedirect.com
Tongue pressure Funami 33
5.
Kohyama K, Hatakeyama E, Dan H, Sasaki T: Effects of sample thickness on bite force for raw carrots and fish gels. J Texture Stud 2005, 36:157-173.
6.
Kohyama K, Nishi M: Direct measurement of biting pressures for crackers using a multiple-point sheet sensor. J Texture Stud 1997, 28:605-617.
7.
Kohyama K, Nishi M, Suzuki T: Measuring texture of crackers with a multiple-point sheet sensor. J Food Sci 1997, 62:922-925.
8.
9.
Kohyama K, Sakai T, Azuma T, Mizuguchi T, Kimura I: Pressure distribution measurement in biting surimi gels with molars using a multiple-point sheet sensor. Biosci Biotechnol Biochem 2001, 65:2597-2603. Kohyama K, Sasaki T, Dan H: Active stress during compression testing of various foods measured by a multiple-point sheet sensor. Biosci Biotechnol Biochem 2003, 67:1492-1498.
10. Nakazawa F, Togashi M: Evaluation of food texture by mastication and palatal pressure, jaw movement and electromyography. In Hydrocolloids Part 2. Edited by Nishinari K. Elsevier Science BV; 2000:473-483. The article studied simultaneous measurements of palatal pressure using transducers embedded in a palatal retainer with other in vivo measurements. 11. Takahashi J, Nakazawa F: Palatal pressure patterns of gelatin gels in the mouth. J Texture Stud 1991, 22:1-11. The article studied the effects of food texture on palatal pressure pattern using transducers embedded in a palatal retainer.
20. Hori K, Ono T, Tamine K, Kondo J, Hamanaka S, Maeda Y, Dong J, Hatsuda M: Newly developed sensor sheet for measuring tongue pressure during swallowing. J Prosthodont Res 2009, 53:28-32. The article described the design and usage of sensor sheet for measuring tongue pressure in comparison with a conventional pressure sensor. 21. Chen J: Food oral processing — a review. Food Hydrocoll 2009, 23:1-25. 22. Shaker R, Cook IJ, Dodds WJ, Hogan WJ: Pressure-flow dynamics of the oral phase of swallowing. Dysphagia 1988, 3:79-84. 23. Tamine K, Ono T, Hori K, Kondoh J, Hamanaka S, Maeda Y: Agerelated changes in tongue pressure during swallowing. J Dent Res 2010, 89:1097-1101. 24. Hirota N, Konaka K, Ono T, Tamine K, Kondo J, Hori K, Yoshimuta Y, Maeda Y, Sakoda S, Naritomi H: Reduced tongue pressure against the hard palate on the paralyzed side during swallowing predicts dysphagia in patients with acute stroke. Stroke 2010, 41:2982-2984. 25. Fujitani J, Uyama R, Ohgoshi H, Kayashita J, Kojo A, Takahashi K, Maeda H, Fujishima I, Ueda K: Japanese dysphagia diet 2013. Jpn J Dysphagia Rehabil 2013, 17:255-267. 26. Quinchia LA, Valencia C, Partal P, Franco JM, Brito-de Fuente E, Gallegos C: Linear and non-linear viscoelasticity of puddings for nutritional management of dysphagia. Food Hydrocoll 2011, 25:586-598.
12. Takahashi J, Nakazawa F: Effects of dimensions of agar and gelatin gels on palatal pressure patterns. J Texture Stud 1992, 23:139-152. The article studied the effects of food dimension on palatal pressure pattern using transducers embedded in a palatal retainer.
27. Li Q, Hori K, Minagi Y, Ono T, Chen Y, Kondo J, Fujiwara S, Tamine K, Hayashi H, Inoue M, Maeda Y: Development of a system to monitor laryngeal movement during swallowing using a bend sensor. PLOS ONE 2013, 8:e70850. The article studied the sequential correlation between the signal waveform from a bend sensor and hyoid bone kinetics recorded by videofluorography.
13. Kumagai H, Tashiro A, Hasegawa A, Kohyama K, Kumagai H: Relationship between flow properties of thickener solutions and their velocity through the pharynx measured by the ultrasonic pulse Doppler method. Food Sci Technol Res 2009, 15:203-210.
28. Li Q, Minagi Y, Hori K, Kondoh J, Fujiwara S, Tamine K, Inoue M, Maeda Y, Chen Y, Ono T: Coordination in oro-pharyngeal biomechanics during human swallowing. Physiol Behav 2015, 147:300-305.
14. Nakazawa F, Ohno M, Morita A, Takahashi J: Ultrasonic measurement of the velocity through the pharynx of swallowed rice boiled with differing water content. J Home Econ Jpn 2000, 51:1067-1071. 15. Clave P, De Kraa M, Arreola V, Girvent M, Farre R, Palomera E, Serra-Prat M: The effect of bolus viscosity on swallowing function in neurogenic dysphagia. Aliment Pharmacol Ther 2006, 24:1385-1394. 16. Okazawa M, Konishi H, Yoshida T, Katsumata A, Iida Y, Fujishita M: Properties of rice porridge (gruel) as a meal for patients with swallowing disorder. J Gifu Dent Soc 2008, 35:7-12. 17. Saitoh E, Shibata S, Matsuo K, Baba M, Fujii W, Palmer JB: Chewing and food consistency: effects on bolus transport and swallow initiation. Dysphagia 2007, 22:100-107. 18. Yokoyama S, Hori K, Tamine K, Fujiwara S, Inoue M, Maeda Y, Funami T, Ishihara S, Ono T: Tongue pressure modulation for initial gel consistency in a different oral strategy. PLOS ONE 2014, 9:e91920. The article studied the effects of food texture on tongue movement using sensor sheet and indicated its usefulness for clarifying oral physiology during size reduction. 19. Hori K, Hayashi H, Yokoyama S, Ono T, Ishihara S, Magara J, Taniguchi H, Funami T, Maeda Y, Inoue M: Comparison of mechanical analyses and tongue pressure analyses during squeezing and swallowing of gels. Food Hydrocoll 2015, 44:145-155. The article studied the effects of food texture on tongue movement using sensor sheet and indicated its usefulness for clarifying oral physiology during squeezing.
www.sciencedirect.com
29. Yano J, Aoyagi Y, Ono T, Hori K, Yamaguchi W, Fujiwara S, Kumakura I, Minagi S, Tsubahara A: Sequential coordination between lingual and pharyngeal pressures produced during dry swallowing. BioMed Res Int 2014. Article ID 691352. 30. Funami T, Isono M, Ikegami A, Nakao S, Nakauma M, Fujiwara S, Minagi Y, Hori K, Ono T: Throat sensations of beverages evaluated by in vivo measurements of swallowing. J Texture Stud 2015, 46:187-199. The article studied the relationship between throat sensations of beverages and the kinetic analysis of the laryngeal movement on a bend sensor. 31. Kieser J, Bolter C, Raniga N, Waddell JN, Swain M, Farland G: Tongue-palate interactions during swallowing. J Texture Stud 2011, 42:95-102. 32. Alsanei WA, Chen J: Studies of the oral capabilities in relation to bolus manipulations and the ease of initiating bolus flow. J Texture Stud 2014, 45:1-12. 33. Alsanei WA, Chen J, Ding R: Food oral breaking and the determining role of tongue muscle strength. Food Res Int 2015, 67:331-337. 34. Ishihara S, Nakao S, Nakauma M, Funami T, Hori K, Ono T, Kohyama K, Nishinari K: Compression test of food gels on artificial tongue and its comparison with human test. J Texture Stud 2013, 44:104-114. 35. Ishihara S, Isono M, Nakao S, Nakauma M, Funami T, Hori K, Ono T, Kohyama K, Nishinari K: Instrumental uniaxial compression test of gellan gels of various mechanical properties using artificial tongue and its comparison with human oral strategy for the first size reduction. J Texture Stud 2014, 45:354-366.
Current Opinion in Food Science 2016, 9:29–33
ScienceDirect Tongue pressure measurement in food science Takahiro Funami Recently published two articles relating to tongue pressure measurement during food oral processing and its usefulness for food texture study are highlighted. Tongue pressure measurement must be a new approach for texture design of food products particularly for specified consumer group with reduced capability of eating. In this article, a novel sensor for the measurement is introduced with emphasizing its advantages which enable natural and habitual eating behavior. Potential usage of the measurement to know the dynamics of food oral processing and to visualize the interaction between a food and the tongue are also indicated. Tongue pressure measurement can contribute to the progress of food texture study on both academic and industrial sides. Address San-Ei Gen F.F.I., Inc., 1-1-11, Sanwa-cho, Toyonaka, Osaka 561-8588, Japan Corresponding author: Funami, Takahiro ([email protected])
Current Opinion in Food Science 2016, 9:29–33 This review comes from a themed issue on Sensory Science and Consumer Perception Edited by Susana Fiszman
http://dx.doi.org/10.1016/j.cofs.2016.04.003 2214-7993/# 2016 Elsevier Ltd. All rights reserved.
Introduction Food texture analysis on human in vivo measurements is now popular in the food science field. Electromyography [1–4], biting force measurement [5–9], palatal pressure measurement [10,11,12], ultrasonic or ultrasound method [13,14], and videofluorography [15–17] are representative and provide us with a lot of insights into food oral management in human. The topic dealt in this article is tongue pressure measurement, and two related articles reported recently by the research team of Osaka University and Niigata University [18,19] are focused. They have been successful in mapping tongue pressure during oral processing using a novel device developed by the research team [20] mainly for clinical purpose. On the basis of the success, they have been trying to visualize the interaction between a food and the tongue during oral processing in human. Since the tongue plays a crucial role throughout food oral processing, which initiates from cognition, followed by size reduction (mastication or www.sciencedirect.com
squeezing), bolus formation, bolus transportation, and swallowing [21], it is reasonable from physiological point of view to link tongue movement with food texture. As a series of their trials, in these two articles, effects of food texture on tongue movement were investigated, and consistency [18] and rheological nature (i.e. elastic or plastic) [19] were selected as a dominating attribute of food texture. The idea of the research team to apply the device to food science is breakthrough.
Apparatus for tongue pressure measurement and its advantages The devise is a T-shaped sensor sheet with five measuring channels (presented as Ch. 1-5) attached to Swallow Scan system (Figure 1), enabling real-time monitoring of tongue pressure based on an electrical transducer mechanism (resistance to electrical current). The devise was originally established to architect the design of palatal plate particularly for tongue cancer patients. Measurement of the contact pressure between the tongue and the hard palate is necessary for customizing of palatal plate because the intensity and the pattern of the contact can change by the shape of the tongue after surgery. There are many technical advantages in the devise which support the idea of the research team. It is only 0.1 mm in thickness with different sizes and mechanical flexibility for easy adaptation to oral shape and does not change the oral physiology nor interfere with the occlusion. Also, the sensor sheet does not cover the overall area of the hard palate and thus does not interfere the perception of taste, aroma, or texture. It does not prevent natural and habitual eating behavior in human, and this must be no doubt the greatest benefit for food texture study. Manometer, in which a small balloon type probe is normally inserted into the oral cavity [22], may not cause too much discomfort to subjects but does not necessarily ensure natural eating. In addition, the devise is wearable and portable, and experiments can be carried out even on chair-side or bed-side. So far, over 20 articles have been published on this system, covering a wide range of research field from clinical, including diagnostic, treatment, and rehabilitation for the elderlies [23], tongue cancer patients, and stroke patients [24], to food texture study and providing the system with scientific validation.
Link of tongue pressure measurement to food texture Most reports on tongue pressure measurement deal with only swallowing but not so frequently with a whole series of food oral processing. Using this system, temporal and spatial distribution pattern of tongue pressure during oral processing is elucidated, and thus human eating behavior Current Opinion in Food Science 2016, 9:29–33
30 Sensory Science and Consumer Perception
Figure 1
(a)
(b)
Ch. 1
Ch. 2
Ch. 3 Ch. 4
Ch. 5
Current Opinion in Food Science
Swallow scan system (a) and location of measuring channels (b).
(or food eaten behavior) can be visualized using tongue movement as a benchmark. Rheological nature of food samples does not basically cause difference in temporal pattern of tongue pressure during squeezing, presenting first onset at the mid-median part (Ch. 2), followed by the anterior-median (Ch. 1) and the posterior-median (Ch. 3) parts and then by the circumferential parts (Chs. 4 and 5) regardless of rheological nature (Figure 2). However, some differences are found between elastic and plastic (i.e. deformable) food samples in offset, and as a result, duration of squeezing for plastic food sample tends to become shorter than that for elastic food sample when consistency is low, whereas vice versa when consistency is high. Also, spatial distribution pattern of tongue pressure during squeezing is different between elastic and plastic food samples; the maximum amplitude at the anteriormedian and mid-median parts are larger than that at the circumferential parts for elastic food sample, whereas no significant difference between channels for plastic food sample (Figure 3). These findings present difference in tongue movement during size reduction caused by food texture and also give us a hint on suitable food texture to specified consumer group with tongue-related digestion disorder.
For product development There must be an intention of the research team to utilize this system for food product development for the elderlies. Usage of polysaccharide gels as a model food is an implication because gel is a dominant food matrix for clinical foods particularly for dysphagic patients as seen in pudding and jellies [25,26]. Decreased capability of generating tongue pressure has implication to eating and swallowing behaviors for the elderlies, and food texture design based on tongue pressure is valid in Current Opinion in Food Science 2016, 9:29–33
this regard. The author believes that concept of ‘comfortable to the tongue’ should lead to innovation of food product development for the elderlies. It is possible to synchronize tongue pressure measurement with other in vivo measurements, and when focusing on swallowing, usage of a bend sensor which monitors the laryngeal movement [27] should be beneficial. Actually, in combination with bend sensor placed on the frontal neck (Figure 4), the coordination between laryngeal movement and hyoid motion during swallowing was elucidated, and the sequential order of tongue pressure and hyoid movement was displayed successfully [28]. In place of bend sensor, manometric catheter is applicable to see the oropharyngeal pressure flow dynamics during swallowing [29]. In addition, bodying sensation of beverages can be assessed by changes in both duration and the activity of the larynx required for one swallowing cycle using bend sensor [30].
For future study Discussion of tongue pressure measurement could be further expanded to cover some important aspects of food oral processing, such as dynamics of swallowing behavior, eating capability assessment, and artificial tongue etc. Tongue movement is basic to understanding the swallowing process, and tongue pressure measurement not only visualizes tongue movement but also clarifies different functions by tongue anatomy [31]. Tongue pressure relates to eating and swallowing capabilities of the elderlies [32,33], and its measurement can provide guidance of food choice for them. Usage of artificial tongue should be an idea for mechanical simulation of palatal reduction (i.e. size reduction by tongue-palate compression) [34,35], and tongue pressure measurement can help fabrication and selection of artificial tongue. www.sciencedirect.com
Tongue pressure Funami 31
Figure 2
Ch. 1 Ch. 2 S1
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
S2
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
S3
Ch. 3 * Ch. 4 Ch. 5 Ch. 1 Ch. 2
G1
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
G2
*
Ch. 3 Ch. 4 Ch. 5 Ch. 1 Ch. 2
G3
Ch. 3
*
*
Ch. 4 Ch. 5 –0.4
–0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4 (s)
Onset
Peak time
Offset Current Opinion in Food Science
Time sequences of tongue pressure at each channel during the initial squeeze. The time ‘0’ was set as the onset of Ch. 1. *p < 0.05 (Kruskal– Wallis test and post hoc test with Bonferroni correction). S1-3 presents rheologically plastic food samples with increased consistency in order, whereas G1-3 presents rheologically elastic food samples with increased consistency in order. When the number is the same, consistency of food sample is equivalent between elastic and plastic food samples.
Food texture is a complex attribute and thus sometimes difficult to comprehend its whole entity. On the other hand, foods without complexity (in terms of appearance, flavor, texture etc.) are boring and not very pleasant for all www.sciencedirect.com
people. To understand such complexity of food texture, collaboration between oral physiology and food science should be strengthened more. For activation and enhancement of such an inter-disciplinal research activity, Current Opinion in Food Science 2016, 9:29–33
32 Sensory Science and Consumer Perception
Figure 3
(kPa) 45
*
40
S1
S2
S3
G1
G2
G3
*
*
* *
35 30
*
25 20 15 10 5 0 Ch. 1
Ch. 2
Ch. 3
Ch. 4
Ch. 5
Maximum amplitude
Instrumental test Current Opinion in Food Science
The maximum amplitude of tongue pressure at each channel during the initial squeeze. *p < 0.05 (one-way ANOVA test and Tukey’s post hoc test). See the footnote in Figure 2 for the sample denomination.
tongue pressure measurement should constitute a core part in the future. From these aspects, contribution of the measurement to the progress of food texture study can be highly expected. Figure 4
Conclusions On the basis of the temporal and special distribution of tongue pressure measured, biomechanics from oral to pharyngeal phase can be evaluated, interactions between human and a food can be visualized, and influences of food texture on the biomechanics can be evaluated. Thus, tongue pressure measurement links well oral physiology to food science and helps develop food products for the elderlies or dysphagic patients required in this aged society. Food scientists thus should study the validity of tongue pressure measurement and should utilize it more for texture design of food products to increase quality of life for these people. The author wishes that this article should lead to the progress of food science particularly food texture study.
References and recommended reading Papers of particular interest, published within the period of review, have been highlighted as: of special interest of outstanding interest
Current Opinion in Food Science
Frontal image of a subject with sensor sheet and bend sensor. Current Opinion in Food Science 2016, 9:29–33
1.
Kohyama K, Nakayama Y, Watanabe H, Sasaki T: Electromyography of eating apples: influence of cooking, cutting, and peeling. J Food Sci 2015, 70:S257-S261.
2.
Kohyama K, Ohtsubo K, Toyoshima H, Shiozawa K: Electromyographic study on cooked rice with different amylose contents. J Texture Stud 1998, 29:101-113.
3.
Kohyama K, Sawada H, Nonaka M, Kobori C, Hayakawa F, Sasaki T: Textural evaluation of rice cake by chewing and swallowing measurements on human subjects. Biosci Biotechnol Biochem 2007, 71:358-365.
4.
Kohyama K, Yamaguchi M, Kobori C, Nakayama Y, Hayakawa F, Sasaki T: Mastication effort estimated by electromyography for cooked rice of differing water content. Biosci Biotechnol Biochem 2005, 69:1669-1676. www.sciencedirect.com
Tongue pressure Funami 33
5.
Kohyama K, Hatakeyama E, Dan H, Sasaki T: Effects of sample thickness on bite force for raw carrots and fish gels. J Texture Stud 2005, 36:157-173.
6.
Kohyama K, Nishi M: Direct measurement of biting pressures for crackers using a multiple-point sheet sensor. J Texture Stud 1997, 28:605-617.
7.
Kohyama K, Nishi M, Suzuki T: Measuring texture of crackers with a multiple-point sheet sensor. J Food Sci 1997, 62:922-925.
8.
9.
Kohyama K, Sakai T, Azuma T, Mizuguchi T, Kimura I: Pressure distribution measurement in biting surimi gels with molars using a multiple-point sheet sensor. Biosci Biotechnol Biochem 2001, 65:2597-2603. Kohyama K, Sasaki T, Dan H: Active stress during compression testing of various foods measured by a multiple-point sheet sensor. Biosci Biotechnol Biochem 2003, 67:1492-1498.
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